Alternus Clean Energy (ALCE) S-1/A 26 Jul 24 IPO registration (amended) Financial data

Document And Entity Information

Document And Entity Information	3 Months Ended
	Mar. 31, 2024
Document Information Line Items
Entity Registrant Name	Alternus Clean Energy, Inc.
Document Type	S-1/A
Amendment Flag	true
Amendment Description	Amendment No. 3
Entity Central Index Key	0001883984
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Incorporation, State or Country Code	DE

Consolidated Balance Sheets (Un

Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Current Assets
Cash and cash equivalents	$ 1,381	$ 4,618	$ 705
Accounts receivable, net	2,119	651	3,335
Unbilled energy incentives earned	6,048	5,607	4,954
Prepaid expenses and other current assets	3,023	3,344	1,482
Taxes recoverable	683	631	1,388
Restricted cash	841	19,161
Current discontinued assets held for sale		80,943
Total Current Assets	14,095	114,955	11,864
Property and equipment, net	61,605	61,302	68,953
Right of use asset	1,303	1,330	1,004
Restricted cash			6,598
Other receivable	1,000	1,483
Capitalized development cost and other long-term assets, net	6,351	6,216	2,146
Non-current discontinued assets held for sale			87,750
Total Assets	84,354	185,286	178,315
Current Liabilities
Accounts payable	10,494	5,084	1,138
Accrued liabilities	19,032	24,410	3,471
Taxes payable	13	14	616
Deferred income	6,048	5,607	4,954
Operating lease liability	177	175	75
Green bonds	87,264	166,122
Convertible and non-convertible promissory notes, net of debt issuance costs	30,615	31,420
Due to affiliate	1,046
Current discontinued liabilities held for sale		14,259
Total Current Liabilities	154,689	247,091	10,254
Green bonds			149,481
Convertible and non-convertible promissory notes, net of debt issuance costs			9,214
Operating lease liability, net of current portion	1,188	1,252	960
Asset retirement obligations	196	197	397
Non-current discontinued liabilities held for sale			10,591
Total Liabilities	156,073	248,540	180,897
Shareholders’ Deficit
Preferred stock value
Common Stock value	8	7	6
Additional paid in capital	28,223	27,874	19,797
Foreign Currency Translation Reserve	(4,156)	(2,924)	(3,638)
Accumulated deficit	(95,794)	(88,211)	(18,747)
Total Shareholders’ Deficit	(71,719)	(63,254)	(2,582)
Total Liabilities and Shareholders’ Deficit	$ 84,354	$ 185,286	$ 178,315

Consolidated Balance Sheets (_2

Consolidated Balance Sheets (Unaudited) (Parentheticals) - $ / shares	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Preferred stock, par value (in Dollars per share)	$ 0.0001	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	1,000,000	1,000,000	1,000,000
Preferred stock, shares issued	0	0	0
Preferred stock, shares outstanding	0	0	0
Common shares, par value (in Dollars per share)	$ 0.0001	$ 0.0001	$ 0.0001
Common shares, shares authorized	150,000,000	150,000,000	150,000,000
Common shares, shares issued	81,396,664	71,905,363	57,500,000
Common shares, shares outstanding	81,396,664	71,905,363	57,500,000

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Income Statement [Abstract]
Revenues	$ 2,180	$ 3,846	$ 20,084	$ 17,089
Operating Expenses
Cost of revenues	(834)	(1,015)	(4,468)	(4,439)
Selling, general and administrative	(3,747)	(1,725)	(11,228)	(5,720)
Depreciation, amortization, and accretion	(568)	(842)	(3,657)	(3,677)
Development Costs	(7)	(111)	(798)	(11,372)
Loss on disposal of assets			(5,501)	(79)
Total operating expenses	(5,156)	(3,693)	(25,652)	(25,287)
Income/(loss) from operations	(2,976)	153	(5,568)	(8,198)
Other income/(expense):
Interest expense	(4,984)	(3,468)	(18,562)	(10,256)
Fair value movement of FPA Asset	(483)		(16,642)
Solis bond waiver fee			(11,232)
Other expense	(223)	(40)	(1,642)	(684)
Other income	7		9	569
Total other expenses	(5,683)	(3,508)	(48,069)	(10,371)
Loss before provision for income taxes	(8,659)	(3,355)	(53,637)	(18,569)
Income taxes			(15)
Net loss from continuing operations	(8,659)	(3,355)	(53,652)	(18,569)
Discontinued operations:
Loss from operations of discontinued business component	(1,074)	(1,897)	(3,885)	141
Gain on sale of discontinued business components	2,150
Impairment loss recognized on the remeasurement to fair value less costs to sell			(11,766)
Income tax			(161)	(21)
Net income/(loss) from discontinued operations	1,076	(1,897)	(15,812)	120
Net loss for the period	(7,583)	(5,252)	(69,464)	(18,449)
Net loss attributable to common stockholders, basic	$ (8,659)	$ (3,355)	$ (53,652)	$ (18,569)
Net loss per share attributable to common stockholders, basic (in Dollars per share)	$ (0.13)	$ (0.06)	$ (0.93)	$ (0.32)
Net loss per share attributable to common stockholders, diluted (in Dollars per share)	$ (0.13)	$ (0.06)	$ (0.93)	$ (0.32)
Weighted-average common stock outstanding, basic (in Shares)	65,077,094	57,500,000	57,862,598	57,500,000
Weighted-average common stock outstanding, diluted (in Shares)	65,077,094	57,500,000	57,862,598	57,500,000
Comprehensive loss:
Net loss	$ (7,583)	$ (5,252)	$ (69,464)	$ (18,449)
Foreign currency translation adjustment	(1,232)	(104)	714	(991)
Comprehensive loss	$ (8,815)	$ (5,356)	$ (68,750)	$ (19,440)

Consolidated Statements of Chan

Consolidated Statements of Changes in Shareholders’ Equity (Deficit) (Unaudited) - USD ($) $ in Thousands	Preferred Stock	Common Stock	Additional Paid-In Capital	Foreign Currency Translation Reserve	Accumulated Deficit	Total
Balance at Dec. 31, 2021			$ 29,220	$ (2,647)	$ (298)	$ 26,275
Balance (in Shares) at Dec. 31, 2021
Retroactive application of Merger		$ 6	(6)
Retroactive application of Merger (in Shares)		57,500,000
Adjusted balance, beginning of period at Dec. 31, 2021		$ 6	29,214	(2,647)	(298)	26,275
Adjusted balance, beginning of period (in Shares) at Dec. 31, 2021		57,500,000
Distribution to stockholder			(15,063)			(15,063)
Contribution from stockholder			5,646			5,646
Foreign currency translation adjustment				(991)		(991)
Net Loss					(18,449)	(18,449)
Balance at Dec. 31, 2022		$ 6	19,797	(3,638)	(18,747)	(2,582)
Balance (in Shares) at Dec. 31, 2022		57,500,000
Distribution to stockholder			(1,853)			(1,853)
Contribution from stockholder			2,015			2,015
Foreign currency translation adjustment				(104)		(104)
Net Loss					(5,252)	(5,252)
Balance at Mar. 31, 2023		$ 6	19,959	(3,742)	(23,999)	(7,776)
Balance (in Shares) at Mar. 31, 2023		57,500,000
Balance at Dec. 31, 2022		$ 6	19,797	(3,638)	(18,747)	(2,582)
Balance (in Shares) at Dec. 31, 2022		57,500,000
Distribution to stockholder			(25,195)			(25,195)
Merger, net of transaction costs		$ 1	(2,341)			(2,340)
Merger, net of transaction costs (in Shares)		11,383,809
Fair Value of penny warrants			1,820			1,820
Issuance of Alternus Clean Energy Inc. common stock to Meteora parties subject to FPA			16,493			16,493
Issuance of Alternus Clean Energy Inc. common stock to Meteora parties subject to FPA (in Shares)		2,796,554
Conversion of promissory note payable to related party for common stock in connection with the Merger			2,005			2,005
Conversion of promissory note payable to related party for common stock in connection with the Merger (in Shares)		225,000
Contribution from stockholder			15,295			15,295
Foreign currency translation adjustment				714		714
Net Loss					(69,464)	(69,464)
Balance at Dec. 31, 2023		$ 7	27,874	(2,924)	(88,211)	(63,254)
Balance (in Shares) at Dec. 31, 2023		71,905,363
Settlement of Related Party Debt for Shares		$ 1	9,836			9,837
Settlement of Related Party Debt for Shares (in Shares)		7,990,000
Conversion of Debt			1,029			1,029
Conversion of Debt (in Shares)		1,320,000
Merger Costs – Settlement of Related Party Debt and Conversion of Debt			(10,633)			(10,633)
Stock Compensation for Third Party Services			117			117
Stock Compensation for Third Party Services (in Shares)		181,301
Foreign currency translation adjustment				(1,232)		(1,232)
Net Loss					(7,583)	(7,583)
Balance at Mar. 31, 2024		$ 8	$ 28,223	$ (4,156)	$ (95,794)	$ (71,719)
Balance (in Shares) at Mar. 31, 2024		81,396,664

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Cash Flows from Operating Activities
Net loss from continuing operations	$ (8,659)	$ (3,355)	$ (53,652)	$ (18,569)
Adjustments to reconcile net income/(loss) to net cash provided used in operations:
Depreciation, amortization and accretion	568	842	3,657	3,677
Amortization of debt discount	698	1,117	4,859	3,871
Credit loss expense	(3)		8
Share-based compensation to third parties	117
Gain (loss) on foreign currency exchange rates	64	113	(187)	288
Fair value movement of FPA Asset	483		16,642
Solis Bond waiver fee			11,232
Loss on disposal of asset	1,348		3,889
Non-cash operating lease assets	(8)	31	(299)	(1,049)
Changes in assets and liabilities, net of effects of acquisitions:
Accounts receivable and other short-term receivables	(89)	2,056	4,047	(2,752)
Prepaid expenses and other assets	199	(491)	(2,776)	2,496
Accounts payable	2,155	278	3,673	(1,225)
Accrued liabilities	(3,292)	599	18,964	3,584
Operating lease liabilities	(48)	(11)	381	1,034
Payable to affiliate	1,039
Net Cash provided by (used in) Operating Activities	(5,428)	1,179	10,438	(8,645)
Net Cash provided by (used in) Operating Activities - Discontinued Operations	(2,085)	(805)	2,774	1,255
Cash Flows from Investing Activities:
Purchases of property and equipment	(1,486)	(124)	(4,737)	(1,154)
Sales of property and equipment	67,540	107	17,364
Capitalized Cost	(228)	(241)	(5,857)	(655)
Construction in Process	(340)	(770)	(7,445)	(3,164)
Net Cash provided by (used in) Investing Activities	65,486	(1,028)	(675)	(4,973)
Net Cash provided by (used in) Investing Activities - Discontinued Operations	0	(52)	(83)	(12,429)
Cash Flows from Financing Activities:
Proceeds from debt	1,109	1,396	15,468	23,961
Payments of debt principal	(77,682)		(210)
Debt Issuance Cost	(315)	(130)	292	(1,407)
Merger proceeds net of transaction costs			(500)
Repayment of shareholder loans				(9,282)
Distributions to parent		(403)	(21,908)	(29,997)
Contributions from parent	253	1,074	15,855	21,731
Net Cash provided by (used in) Financing Activities	(76,635)	1,937	8,997	5,006
Net Cash provided by (used in) Financing Activities - Discontinued Operations	(3,151)	(325)	(5,067)	7,325
Effect of exchange rate on cash	(528)	215	433	(558)
Net increase (decrease) in cash, cash equivalents and restricted cash	(22,341)	1,121	16,817	(13,019)
Cash, cash equivalents, and restricted cash beginning of the year	24,563	7,747	7,747	20,766
Cash, cash equivalents, and restricted cash end of the year	2,222	8,868	24,563	7,747
Cash Reconciliation
Cash and cash equivalents	1,381	2,090	5,403	1,149
Restricted cash	841	6,778	19,161	6,598
Cash, cash equivalents, and restricted cash end of the year	2,222	8,868	24,564	7,747
Supplemental Cash Flow Disclosure
Interest (net of capitalized interest of 397 and 87 respectively)			7,321	3,828
Interest (net of capitalized interest of 47 and 64 respectively)	5,287	1,920
Taxes	526	777	2,488	2,015
Non-cash financing activities:
Shares issued for settlement of debt	9,836
Shares issued for conversion of debt	1,029
Shares issued for stock compensation to third parties	117
Previously Reported
Cash Flows from Financing Activities:
Cash, cash equivalents, and restricted cash beginning of the year	$ 24,564	$ 7,747	7,747
Cash, cash equivalents, and restricted cash end of the year			$ 24,564	$ 7,747

Consolidated Statements of Ca_2

Consolidated Statements of Cash Flows (Unaudited) (Parentheticals) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Statement of Cash Flows [Abstract]
Net of capitalized interest	$ 47	$ 64	$ 397	$ 87

Organization and Formation

Organization and Formation	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Organization and Formation [Abstract]
Organization and Formation	1. Organization and Formation Alternus Clean Energy, Inc. (the “Company”) was incorporated in Delaware on May 14, 2021 and was originally known as Clean Earth Acquisitions Corp. (“Clean Earth”). On October 12, 2022, Clean Earth entered into a Business Combination Agreement, as amended by that certain First Amendment to the Business Combination Agreement, dated as of April 12, 2023 (the “First BCA Amendment”) (as amended by the First BCA Amendment, the “Initial Business Combination Agreement”), and as amended and restated by that certain Amended and Restated Business Combination Agreement, dated as of December 22, 2023 (the “A&R BCA”) (the Initial Business Combination Agreement, as amended and restated by the A&R BCA, the “Business Combination Agreement”), by and among Clean Earth, Alternus Energy Group Plc (“AEG”) and the Sponsor. Following the approval of the Initial Business Combination Agreement and the transactions contemplated thereby at the special meeting of the stockholders of Clean Earth held on December 4, 2023, the Company consummated the Business Combination on December 22, 2023. In accordance with the Business Combination Agreement, Clean Earth issued and transferred 57,500,000 shares of common stock of Clean Earth, par value $0.0001 per share, to AEG, and AEG transferred to Clean Earth, and Clean Earth received from AEG, all of the issued and outstanding equity interests in the Acquired Subsidiaries (as defined in the Business Combination Agreement) (the “Equity Exchange,” and together with the other transactions contemplated by the Business Combination Agreement, the “Business Combination”). In connection with the Closing, the Company changed its name from Clean Earth Acquisition Corp. to Alternus Clean Energy, Inc. Clean Earth’s only pre-combination assets were cash and investments and the SPAC did not meet the definition of a business in accordance with U.S. GAAP. Therefore, the substance of the transaction was a recapitalization of the target (AEG) rather than a business combination or an asset acquisition. In such a situation, the transaction is accounted for as though the target issued its equity for the net assets of the SPAC and, since a business combination has not occurred, no goodwill or intangible assets would be recorded. As such, AEG is considered the accounting acquirer and these consolidated financial statements represent a continuation of AEG’s financial statements. Assets and liabilities of AEG are presented at their historical carrying values. Alternus Clean Energy Inc. is a holding company that operates through the following forty-two operating subsidiaries as of March 31, 2024: Subsidiary Principal Date Acquired / ALCE Ownership Country of Power Clouds S.r.l. SPV 31 March 2015 Solis Bond Company DAC Romania F.R.A.N. Energy Investment S.r.l. SPV 31 March 2015 Solis Bond Company DAC Romania PC-Italia-01 S.r.l. Sub-Holding SPV 15 May 2015 AEG MH 02 Limited Italy PC-Italia-03 S.r.l. SPV 1 July 2020 AEG MH 02 Limited Italy PC-Italia-04 S.r.l. SPV 15 July 2020 AEG MH 02 Limited Italy Solis Bond Company DAC Holding Company 16 October 2020 AEG JD 03 Limited Ireland ALT US 03, LLC LLC 4 May 2022 ALT US 03 LLC USA Alternus Energy Americas Inc. Holding Company 10 May 2021 Alternus Energy Group Pl USA LJG Green Source Energy Beta S.r.l SPV 29 July 2021 Solis Bond Company DAC Romania Ecosfer Energy S.r.l. SPV 30 July 2021 Solis Bond Company DAC Romania Lucas EST S.r.l. SPV 30 July 2021 Solis Bond Company DAC Romania Risorse Solari I S.r.l. SPV 28 September 2019 AEG MH 02 Limited Italy Risorse Solari III S.r.l. SPV 3 August 2021 AEG MH 02 Limited Italy Alternus Iberia S.L. SPV 4 August 2021 AEG MH 02 Limited Spain AED Italia-01 S.r.l. SPV 22 October 2021 AEG MH 02 Limited Italy AED Italia-02 S.r.l. SPV 22 October 2021 AEG MH 02 Limited Italy AED Italia-03 S.r.l. SPV 22 October 2021 AEG MH 02 Limited Italy AED Italia-04 S.r.l. SPV 22 October 2021 AEG MH 02 Limited Italy AED Italia-05 S.r.l. SPV 22 October 2021 AEG MH 02 Limited Italy ALT US 01 LLC SPV 6 December 2021 Alternus Energy Americas Inc. USA AEG MH 01 Limited Holding Company 8 March 2022 Alternus Lux 01 S.a.r.l. Ireland AEG MH 02 Limited Holding Company 8 March 2022 AEG JD 03 Limited Ireland ALT US 02 LLC Holding Company 8 March 2022 Alternus Energy Americas Inc. USA AEG JD 01 Limited Holding Company 16 March 2022 AEG MH 03 Limited Ireland Alternus Europe Limited (f/k/a AEG JD 03 Limited) Holding Company 21 March 2022 Alternus Lux 01 S.a.r.l. Ireland Alt Spain 03, S.L.U. SPV 31 May 2022 Alt Spain Holdco S.L. Spain AEG MH 03 Limited Holding Company 10 June 2022 AEG MH 01 Limited Ireland Lightwave Renewables, LLC SPV 29 June 2022 ALT US 02 LLC USA Alt Spain Holdco, S.L.U. Holding Company Acquired 14 July 2022 AEG MH 02 Limited Spain AED Italia-06 S.r.l. SPV 2 August 2022 AEG MH 02 Limited Italy AED Italia-07 S.r.l. SPV 2 August 2022 AEG MH 02 Limited Italy AED Italia-08 S.r.l. SPV 5 August 2022 AEG MH 02 Limited Italy ALT US 04 LLC Holding Company 14 September 2022 Alternus Energy Americas Inc. USA Alternus LUX 01 S.a.r.l. Holding Company 5 October 2022 Alternus Energy Group Plc Luxembourg Alt Spain 04, S.L.U. SPV May 2022 Alt Spain Holdco, S.L.U. Spain Alt Alliance LLC Holding Company September 2023 Alternus Energy Amercias Inc. USA ALT US 05 LLC Holding Company September 2023 Alternus Energy Americas Inc. USA ALT US 06 LLC Holding Company October 2023 Alternus Energy Americas Inc. USA ALT US 07 LLC Holding Company November 2023 Alternus Energy Americas Inc. USA AEG MH 04 Limited Holding Company January 2024 AEG MH 04 Limited Ireland ALT US 08 LLC Holding Company January 2024 Alternus Energy Americas Inc. USA ALT US AM LLC Holding Company March 2024 Alternus Energy Americas Inc. USA	1. Organization and Formation Alternus Clean Energy, Inc. (the “Company”) was incorporated in Delaware on May 14, 2021 and was originally known as Clean Earth Acquisitions Corp. (“Clean Earth”). On October 12, 2022, Clean Earth entered into a Business Combination Agreement, as amended by that certain First Amendment to the Business Combination Agreement, dated as of April 12, 2023 (the “First BCA Amendment”) (as amended by the First BCA Amendment, the “Initial Business Combination Agreement”), and as amended and restated by that certain Amended and Restated Business Combination Agreement, dated as of December 22, 2023 (the “A&R BCA”) (the Initial Business Combination Agreement, as amended and restated by the A&R BCA, the “Business Combination Agreement”), by and among Clean Earth, Alternus Energy Group Plc (“AEG”) and the Sponsor. Following the approval of the Initial Business Combination Agreement and the transactions contemplated thereby at the special meeting of the stockholders of Clean Earth held on December 4, 2023, the Company consummated the Business Combination on December 22, 2023. In accordance with the Business Combination Agreement, Clean Earth issued and transferred 57,500,000 shares of common stock of Clean Earth, par value $0.0001 per share, to AEG, and AEG transferred to Clean Earth, and Clean Earth received from AEG, all of the issued and outstanding equity interests in the Acquired Subsidiaries (as defined in the Business Combination Agreement) (the “Equity Exchange,” and together with the other transactions contemplated by the Business Combination Agreement, the “Business Combination”). In connection with the Closing, the Company changed its name from Clean Earth Acquisition Corp. to Alternus Clean Energy, Inc. Clean Earth’s only precombination assets were cash and investments and the SPAC did not meet the definition of a business in accordance with U.S. GAAP. Therefore, the substance of the transaction was a recapitalization of the target (AEG) rather than a business combination or an asset acquisition. In such a situation, the transaction is accounted for as though the target issued its equity for the net assets of the SPAC and, since a business combination has not occurred, no goodwill or intangible assets would be recorded. As such, AEG is considered the accounting acquirer and these consolidated financial statements represent a continuation of AEG’s financial statements. Assets and liabilities of AEG are presented at their historical carrying values. Alternus Clean Energy Inc. is a holding company that operates through the following forty-seven operating subsidiaries as of December 31, 2023: Subsidiary Principal Date Acquired / ALTN Ownership Country of Power Clouds S.r.l. SPV 31 March 2015 Solis Bond Company DAC Romania F.R.A.N. Energy Investment S.r.l. SPV 31 March 2015 Solis Bond Company DAC Romania PC-Italia-01 S.r.l. Sub-Holding SPV 15 May 2015 AEG MH 02 Limited Italy Zonnepark Rilland B.V. SPV 20 December 2019 Solis Bond Company DAC Netherlands PC-Italia-03 S.r.l. SPV 1 July 2020 AEG MH 02 Limited Italy PC-Italia-04 S.r.l. SPV 15 July 2020 AEG MH 02 Limited Italy Solis Bond Company DAC Holding Company 16 October 2020 AEG JD 03 Limited Ireland ALT US 03, LLC LLC Acquired 15 December 2020 ALT US 03 LLC USA Alternus Energy Americas Inc. Holding Company 10 May 2021 Alternus Energy Group Pl USA LJG Green Source Energy Beta S.r.l SPV 29 July 2021 Solis Bond Company DAC Romania Ecosfer Energy S.r.l. SPV 30 July 2021 Solis Bond Company DAC Romania Lucas EST S.r.l. SPV 30 July 2021 Solis Bond Company DAC Romania Risorse Solari I S.r.l. SPV 28 September 2019 AEG MH 02 Limited Italy Risorse Solari III S.r.l. SPV 3 August 2021 AEG MH 02 Limited Italy Alternus Iberia S.L. SPV 4 August 2021 AEG MH 02 Limited Spain Solarpark Samas Sp. z o.o. SPV 31 August 2021 Solis Bond Company DAC Poland AED Italia-01 S.r.l. SPV 22 October 2021 AEG MH 02 Limited Italy AED Italia-02 S.r.l. SPV 22 October 2021 AEG MH 02 Limited Italy AED Italia-03 S.r.l. SPV 22 October 2021 AEG MH 02 Limited Italy AED Italia-04 S.r.l. SPV 22 October 2021 AEG MH 02 Limited Italy AED Italia-05 S.r.l. SPV 22 October 2021 AEG MH 02 Limited Italy ALT US 01 LLC SPV 6 December 2021 Alternus Energy Americas Inc. USA Elektrownia PV Komorowo Sp. z o.o. SPV 22 December 2021 Solis Bond Company DAC Poland PV Zachod Sp. z o.o. SPV 22 December 2021 Solis Bond Company DAC Poland AEG MH 01 Limited Holding Company 8 March 2022 Alternus Lux 01 S.a.r.l. Ireland AEG MH 02 Limited Holding Company 8 March 2022 AEG JD 03 Limited Ireland ALT US 02 LLC Holding Company 8 March 2022 Alternus Energy Americas Inc. USA AEG JD 01 Limited Holding Company 16 March 2022 AEG MH 03 Limited Ireland AEG JD 03 Limited Holding Company 21 March 2022 Alternus Lux 01 S.a.r.l. Ireland RA01 Sp. z o.o. SPV 24 March 2022 Solis Bond Company DAC Poland Gardno Sp. z o.o. SPV 24 March 2022 Solis Bond Company DAC Poland Gardno2 Sp. z o.o. SPV 24 March 2022 Solis Bond Company DAC Poland ALT US 03 LLC SPV 4 May 2022 Alternus Energy Americas Inc. USA Alt Spain 03, S.L.U. SPV 31 May 2022 Alt Spain Holdco S.L. Spain AEG MH 03 Limited Holding Company 10 June 2022 AEG MH 01 Limited Ireland Lightwave Renewables, LLC SPV Acquired 29 June 2022 ALT US 02 LLC USA Alt Spain Holdco, S.L.U. (NF Projects S.L) Holding Company Acquired 14 July 2022 AEG MH 02 Limited Spain AED Italia-06 S.r.l. SPV 2 August 2022 AEG MH 02 Limited Italy AED Italia-07 S.r.l. SPV 2 August 2022 AEG MH 02 Limited Italy AED Italia-08 S.r.l. SPV 5 August 2022 AEG MH 02 Limited Italy ALT US 04 LLC Holding Company 14 September 2022 Alternus Energy Americas Inc. USA Alternus LUX 01 S.a.r.l. Holding Company 5 October 2022 Alternus Energy Group Plc Luxembourg Alt Spain 04, S.L.U. SPV May 2022 Alt Spain Holdco, S.L.U. Spain Alt Alliance LLC Holding Company September 2023 Alternus Energy Amercias Inc. USA ALT US 05 LLC Holding Company September 2023 Alternus Energy Americas Inc. USA ALT US 06 LLC Holding Company October 2023 Alternus Energy Americas Inc. USA ALT US 07 LLC Holding Company November 2023 Alternus Energy Americas Inc. USA

Going Concern and Management's

Going Concern and Management's Plans	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Going Concern and Management’s Plans [Abstract]
Going Concern and Management's Plans	2. Going Concern and Management’s Plans The Company has evaluated whether there are certain conditions and events, considered in the aggregate, that raise substantial doubt about the Company's ability to continue as a going concern within one year after the date that the Condensed Consolidated Financial Statements are issued. Based on its recurring losses from operations since inception and continued cash outflows from operating activities (all as described below), the Company has concluded that there is substantial doubt about its ability to continue as a going concern for a period of one year from the date that these Condensed Consolidated Financial Statements were issued. The accompanying consolidated financial statements have been prepared on a going concern basis, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business. As shown in the accompanying consolidated financial statements during the period ended March 31, 2024, the Company had net loss from continuing operations of ($8.7) million and a net loss of ($3.4) million for the three months ended March 31, 2024 and 2023. The Company had total shareholders’ equity/(deficit) of ($71.7) million as of March 31, 2024 and ($63.3) million at December 31, 2023. The Company had $1.4 million of unrestricted cash on hand as of March 31, 2024. Our operating revenues are insufficient to fund our operations and our assets already are pledged to secure our indebtedness to various third party secured creditors, respectively. The unavailability of additional financing could require us to delay, scale back, or terminate our acquisition efforts as well as our own business activities, which would have a material adverse effect on the Company and its viability and prospects. The terms of our indebtedness, including the covenants and the dates on which principal and interest payments on our indebtedness are due, increases the risk that we will be unable to continue as a going concern. To continue as a going concern over the next twelve months, we must make payments on our debt as they come due and comply with the covenants in the agreements governing our indebtedness or, if we fail to do so, to (i) negotiate and obtain waivers of or forbearances with respect to any defaults that occur with respect to our indebtedness, (ii) amend, replace, refinance, or restructure any or all of the agreements governing our indebtedness, and/or (iii) otherwise secure additional capital. However, we cannot provide any assurances that we will be successful in accomplishing any of these plans. As of March 31, 2024, Solis was in breach of the three financial covenants under Solis’ Bond terms: (i) the minimum Liquidity Covenant that requires the higher of €5.5 million or 5% of the outstanding Nominal Amount, (ii) the minimum Equity Ratio covenant of 25%, and (iii) the Leverage Ratio of NIBD/EBITDA to not be higher than 6.5 times for the year ended December 2021, 6.0 times for the year ended December 31, 2022 and 5.5 times for the period ending on the maturity date of the Bond. The Solis Bond carries a 3 months EURIBOR plus 6.5% per annum interest rate, and has quarterly interest payments, with a bullet payment to be paid on the Maturity Date. The Solis Bond is senior secured through a first priority pledge on the shares of Solis and its subsidiaries, a parent guarantee from Alternus Energy Group Plc, and a first priority assignment over any intercompany loans. Additionally, Solis bondholders hold a preference share in an Alternus holding company which holds certain development projects in Spain and Italy. The preference share gives the bondholders the right on any distributions up to EUR 10 million, and such assets will be divested to ensure repayment of up to EUR. 10 million should it not be fully repaid by the Maturity Date. Additionally, because Solis was unable to fully repay the Solis Bonds by September 30, 2023, Solis’ bondholders have the right to immediately transfer ownership of Solis and all of its subsidiaries to the bondholders and proceed to sell Solis’ assets to recoup the full amount owed to the bondholders which as of March 31, 2024 is currently €80.8 million (approximately $87.3 million). If the ownership of Solis and all of its subsidiaries were to be transferred to the Solis bondholders, the majority of the Company’s operating assets and related revenues and EBIDTA would be eliminated, and debt would be reduced by $87.3 million. On October 16 2023, bondholders approved to further extend the temporary waiver to December 16, 2023. On December 18, 2023, a representative group of the bondholders approved an extension of the temporary waivers and the maturity date of the Solis Bonds until January 31, 2024, with the right to further extend to February 29, 2024 at the Solis Bond trustee’s discretion, which was subsequently approved by a majority of the bondholders on January 3, 2024. On March 12, 2024, the Solis Bondholders approved resolutions to further extend the temporary waivers and the maturity date until April 30, 2024 with the right to further extend to May 31, 2024 at the Bond Trustee’s discretion, which it granted, and thereafter on a month-to-month basis to November 29, 2024 at the Bond Trustee’s discretion and approval from a majority of Bondholders. As such, the Solis bond debt is currently recorded as short-term debt. On December 28, 2023, Solis sold 100% of the share capital in its Italian subsidiaries for approximately €15.8 million (approximately $17.5 million). On January 18, 2024, Solis sold 100% of the share capital in its Polish subsidiaries for approximately €54.4 million (approximately $59.1 million), and on February 21, 2024 Solis sold 100% of the share capital of its Netherlands subsidiary for approximately €6.5 million (approximately $7 million). Additionally, on February 14, 2024, Solis exercised its call options to repay €59,100,000 million (approximately $68.5 million) of amounts outstanding under the bonds. Subsequently, on May 1, 2024 Solis made an interest payment of €1,000,000 (approx. $1,069,985.00) to the Bondholders, which is approximately 50% of the total interest due for the first quarter of 2024. The remaining interest amount is expected to be paid alongside, and in addition to, the next interest payment due July 6, 2024 from Solis’ ongoing business operations. Solis will incur a late payment penalty in accordance with the Bond Terms, which will also be paid in July 2024. On March 20, 2024, we received a letter from the Nasdaq Listing Qualifications Staff of The Nasdaq Stock Market LLC therein stating that for the 32 consecutive business day period between February 2, 2024 through March 19, 2024, the Common Stock had not maintained a minimum closing bid price of $1.00 per share required for continued listing on The Nasdaq Capital Market pursuant to Nasdaq Listing Rule 5550(a)(2) (the “Bid Price Rule”). Pursuant to Nasdaq Listing Rule 5810(c)(3)(A), the Company was provided an initial period of 180 calendar days, or until September 16, 2024 (the “Compliance Period”), to regain compliance with the Bid Price Rule. If the Company does not regain compliance with the Bid Price Rule by September 16, 2024, the Company may be eligible for an additional 180-day period to regain compliance. If the Company cannot regain compliance during the Compliance Period or any subsequently granted compliance period, the Common Stock will be subject to delisting. At that time, the Company may appeal the delisting determination to a Nasdaq hearings panel. The notice from Nasdaq has no immediate effect on the listing of the Common Stock and the Common Stock will continue to be listed on The Nasdaq Capital Market under the symbol “ALCE.” The Company is currently evaluating its options for regaining compliance. There can be no assurance that the Company will regain compliance with the Bid Price Rule or maintain compliance with any of the other Nasdaq continued listing requirements. On May 6, 2024, the Company received a letter from the listing qualifications department staff of The Nasdaq Stock Market (“Nasdaq”) notifying the Company that for the last 30 consecutive business days, the Company’s minimum Market Value of Listed Securities (“MVLS”) was below the minimum of $35 million required for continued listing on the Nasdaq Capital Market pursuant to Nasdaq listing rule 5550(b)(2). The notice has no immediate effect on the listing of the Company’s common stock, and the Company’s common stock continues to trade on the Nasdaq Capital Market under the symbol “ALCE.” In accordance with Nasdaq listing rule 5810(c)(3)(C), the Company has 180 calendar days, or until November 4, 2024, to regain compliance. The notice states that to regain compliance, the Company’s MVLS must close at $35 million or more for a minimum of ten consecutive business days (or such longer period of time as the Nasdaq staff may require in some circumstances, but generally not more than 20 consecutive business days) during the compliance period ending November 4, 2024. If the Company does not regain compliance by November 4, 2024, Nasdaq staff will provide written notice to the Company that its securities are subject to delisting. At that time, the Company may appeal any such delisting determination to a Hearings Panel. The Company intends to actively monitor the Company’s MVLS between now and November 4, 2024 and may, if appropriate, evaluate available options to resolve the deficiency and regain compliance with the MVLS rule. While the Company is exercising diligent efforts to maintain the listing of its common stock on Nasdaq, there can be no assurance that the Company will be able to regain or maintain compliance with Nasdaq listing standards. The Company is currently working on several processes to address the going concern issue. We are working with multiple global banks and funds to secure the necessary project financing to execute on our transatlantic business plan.	2. Going Concern and Management’s Plans Our consolidated financial statements for the year ended December 31, 2023, identifies the existence of certain conditions that raise substantial doubt about our ability to continue as a going concern for twelve months from the issuance of this report: The accompanying consolidated financial statements have been prepared on a going concern basis, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business. As shown in the accompanying consolidated financial statements during the period ended December 31, 2023, the Company had net loss from continuing operations of ($53.7) million and a net loss of ($18.6) million for the year ended December 31, 2023 and 2022. The Company had total shareholders’ equity/(deficit) of ($63.3) million as of December 31, 2023 and ($2.6) million at December 31, 2022. The Company had $4.6 million of unrestricted cash on hand as of December 31, 2023. Our operating revenues are insufficient to fund our operations and our assets already are pledged to secure our indebtedness to various third party secured creditors, respectively. The unavailability of additional financing could require us to delay, scale back or terminate our acquisition efforts as well as our own business activities, which would have a material adverse effect on the Company and its viability and prospects. The terms of our indebtedness, including the covenants and the dates on which principal and interest payments on our indebtedness are due, increases the risk that we will be unable to continue as a going concern. To continue as a going concern over the next twelve months, we must make payments on our debt as they come due and comply with the covenants in the agreements governing our indebtedness or, if we fail to do so, to (i) negotiate and obtain waivers of or forbearances with respect to any defaults that occur with respect to our indebtedness, (ii) amend, replace, refinance or restructure any or all of the agreements governing our indebtedness, and/or (iii) otherwise secure additional capital. However, we cannot provide any assurances that we will be successful in accomplishing any of these plans. As of December 31, 2022, Solis was in breach of the three financial covenants under Solis’ Bond terms: (i) the minimum Liquidity Covenant that requires the higher of €5.5 million or 5% of the outstanding Nominal Amount, (ii) the minimum Equity Ratio covenant of 25%, and (iii) the Leverage Ratio of NIBD/EBITDA to not be higher than 6.5 times for the year ended December 2021, 6.0 times for the year ended December 31, 2022 and 5.5 times for the period ending on the maturity date of the Bond, January 6, 2024. The Solis Bond carries a 3 months EURIBOR plus 6.5% per annum interest rate, and has quarterly interest payments, with a bullet payment to be paid on January 6, 2024. The Solis Bond is senior secured through a first priority pledge on the shares of Solis and its subsidiaries, a parent guarantee from Alternus Energy Group Plc, and a first priority assignment over any intercompany loans. In April 2023 the bondholders approved a temporary waiver and an amendment to the bond terms to allow for a change of control in Solis (which allows for the transfer of Solis and its subsidiaries underneath Clean Earth Acquisitions Corp. on Business Combination Closing). In addition, bondholders received a preference share in an Alternus holding company, AEG JD 02 Limited, which holds certain development projects in Spain and Italy. The shares will have preference on any distribution up to €10 million, and AEG JD 02 will divest assets to ensure repayment of the €10 million should the bonds not have been fully repaid at maturity (January 6, 2024). Finally, bondholders will receive a 1% amendment fee, which equates to €1.4 million. On June 5, 2023 the bondholders approved an extension to the waiver to September 30, 2023 and the bond trustee was granted certain additional information rights and the right to appoint half of the members of the board of directors of Solis, in addition to the members of the board appointed by the Company. Under the waiver agreement, as extended, Solis must fully repay the Bonds by September 30, 2023. If Solis is unable to fully repay the Solis Bonds by September 30, 2023, Solis’ bondholders have the right to immediately transfer ownership of Solis and all of its subsidiaries to the bondholders and proceed to sell Solis’ assets to recoup the full amount owed to the bondholders, which as of September 30, 2023 is currently €150,000,000 (approximately $159,000,000). If the ownership of Solis and all of its subsidiaries were to be transferred to the Solis bondholders, the majority of the Company’s operating assets and related revenues and EBIDTA would be eliminated. On October 16 2023, bondholders approved to further extend the temporary waiver to December 16, 2023. On December 18, 2023, a representative group of the bondholders approved an extension of the temporary waivers and the maturity date of the Solis Bonds until January 31, 2024, with the right to further extend to February 29, 2024 at the Solis Bond trustee’s discretion, which was subsequently approved by a majority of the bondholders on January 3, 2024. On March 12, 2024, the bondholders approved an additional extension to April 30, 2024. As such, the Solis bond debt is currently recorded as short-term debt. On December 28, 2023, Solis sold 100% of the share capital in its Italian subsidiaries for approximately €15.8 million (approximately $17.5 million). Subsequently, on January 18, 2024, Solis sold 100% of the share capital in its Polish subsidiaries for approximately € € €59,100,000 million (approximately $68.5 million) of amounts outstanding under the bonds The Company is currently working on several processes to address the going concern issue. In January of 2024, ALCE filed an S1 with the SEC in order to raise additional funds in the first half of 2024. We are working with multiple global banks and funds to secure the necessary project financing to execute on our transatlantic business plan.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Summary of Significant Accounting Policies [Abstract]
Summary of Significant Accounting Policies	3. Summary of Significant Accounting Policies Basis of Presentation The Company prepares its consolidated financial statements in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”). Basis of Consolidation The consolidated financial statements include the financial statements of the Company and its subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation. The results of subsidiaries acquired or disposed of during the respective periods are included in the consolidated financial statements from the effective date of acquisition or up to the effective date of disposal, as appropriate. The consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and the related notes for the year ended December 31, 2023, contained in the Company’s Annual Report on Form 10- k Recent Accounting Pronouncements In December 2023, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures to enhance the transparency of income tax disclosures relating to the rate reconciliation, disclosure of income taxes paid, and certain other disclosures. The ASU should be applied prospectively and is effective for annual periods beginning after December 15, 2024, with early adoption permitted. The Company is currently evaluating the impact on the related disclosures; however, it does not expect this update to have an impact on its financial condition or results of operations. In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures to improve the disclosures about reportable segments and include more detailed information about a reportable segment’s expenses. This ASU also requires that a public entity with a single reportable segment, provide all of the disclosures required as part of the amendments and all existing disclosures required by Topic 280. The ASU should be applied retrospectively to all prior periods presented in the financial statements and is effective for fiscal years beginning after December 15, 2023 and interim periods within fiscal years beginning after December 15, 2024. Early adoption is permitted. The Company is currently evaluating the impact on the financial statements and related disclosures.	3. Summary of Significant Accounting Policies Basis of Presentation The Company prepares its consolidated financial statements in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”). Basis of Consolidation The consolidated financial statements include the financial statements of the Company and its subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation. The results of subsidiaries acquired or disposed of during the respective periods are included in the consolidated financial statements from the effective date of acquisition or up to the effective date of disposal, as appropriate. Related Party Transactions A Related Party transaction is any transaction, arrangement or relationship, or any series of similar transactions, arrangements or relationships, in which (i) the Company or any of its subsidiaries is or will be a participant, and (ii) any Related Party has or will have a direct or indirect interest. A Related Party is any person who is or was (since the beginning of the last fiscal year even if such person does not presently serve in that role) an executive officer or director of the Company, any shareholder owning more than 5% of any class of the Company’s voting securities, or an immediate family member of any such person. Financial assets and financial liabilities are recognized when the Company becomes a party to the contractual provisions of the instrument. Refer to Footnote 25 for more details. Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses for the periods presented. Significant items subject to such estimates include, but are not limited to, the assumptions utilized in the valuation of the assets acquired and liabilities assumed, determination of a business combination or asset acquisition, impairment of long-lived assets, measurement of level 3 fair value assets, and recovery of capitalized cost. Management evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors, including the current economic environment, and makes adjustment when facts and circumstance dictate. These estimates are based on information available as of the date of financial statements; therefore, actual results could differ from these estimates. S egments The Company has two operating segments, U.S. Operations and European Operations, and the decision-making group is the CEO and CFO of the Company (as a group). The CODM regularly review the Reporting Packs that contain financial and operational results aggregated by geography as well as consolidated income statement, balance sheet, and equity of the overall company. Cash and Cash Equivalents The Company considers cash and highly liquid investments with original maturities of three months or less to be cash and cash equivalents. The Company maintains cash and cash equivalents with major financial institutions, the largest concentration in JP Morgan in the U.S, Ireland, and Italy, Unicredit in Romania, and with ING in Poland and the Netherlands. The Company may at times exceed federally insured limits or statutorily insured limits in a foreign jurisdiction. The Company periodically assesses the financial condition and due to the size and stability of the institutions believes the risk of loss to be remote. Restricted Cash Restricted cash relates to balances that are in the bank accounts for specific defined purposes and cannot be used for any other undefined purposes. Restricted cash is primarily restricted stemming from requirements under the Green Bond terms. The balance has a debt service reserve account, per the requirements from the Bond Trustee, that issues quarterly coupons to the Bond holders. Accounts Receivable Accounts receivable are uncollateralized customer obligations due under normal trade terms requiring payment within that period. Accounts receivables are presented net of allowance for doubtful accounts. The Company establishes an allowance for doubtful customer accounts, through a review of historical losses, customer balances, and industry economic conditions. Under the expected loss model, a loss (or allowance) is recognized upon initial recognition of the asset that reflects all future events that may lead to a loss being realized, regardless of whether it is probable that the future event will occur. The Company extends credit based on an evaluation of customers’ financial condition and determines any additional collateral requirements. Exposure to losses on receivables is principally dependent on each customer’s financial condition. The Company considers invoices past due when they are outstanding longer than the stated term. Under the expected loss model, a loss (or allowance) is recognized upon initial recognition of the asset that reflects all future events that may lead to a loss being realized, regardless of whether it is probable that the future event will occur. Management considers the carrying value of accounts receivable to be fully collectible. If amounts become uncollectible, they are charged to operations in the period in which that determination is made. The allowance for credit losses was $7 thousand an $0 as of December 31, 2023 and 2022 respectively. Concentration of Credit Risk At times, the Company maintains cash balances in financial institutions which may exceed federally insured limits. The Company maintains cash balances in all countries in which it operates and in Ireland where the Company is headquartered. Government coverage for the Company’s cash balances are as follows: ● European Union - $105,841 (€100,000) per account is covered for operations in Romania, Poland, Italy, the Netherlands, and the Company’s headquarters in Ireland. ● United States - $250,000 The Company has four cash accounts across the European countries and a net of $18.8 million above government insurance amounts. The Company has six cash accounts across the United States and a net of $2.5 million above the government insurance amounts. The Company has not experienced any losses relating to such accounts and believes it is not exposed to significant credit risk on its cash and cash equivalents or restricted cash. Additionally, one customer represented 35% of continuing operational revenues during the year ended December 31, 2023 and three customers represented 61% of the Company’s continuing operational accounts receivable for the year ended December 31, 2023. These concentrations represent a risk to revenues and cash flows should these customers face financial difficulties. Economic Concentrations The Company and its subsidiaries own and operate solar generating facilities installed on buildings and land located across Europe and the US. Future operations could be affected by changes in the economy, other conditions in those geographic areas or by changes in the demand for renewable energy. Property and Equipment Property and equipment are stated at cost less accumulated depreciation, amortization and impairment. The cost of an asset comprises its purchase price and any directly attributable costs of bringing the asset to its present working condition and location for its intended use. Depreciation is computed on a straight-line basis over the estimated useful lives. The useful lives per asset class are as follows: ● Solar Energy Facilities carry a useful life of the lesser of 35 years from the original placed in-service date or the lease term of the land on which they are built. ● Leasehold improvements are amortized over the shorter of the lease term or their estimated useful file. ● Furniture and fixtures carry a useful life of 3 years. ● Software and computer equipment carry a useful life of 3 and 5 years respectively. Expenditures for major renewals and betterments which substantially extend the useful life of assets are capitalized. Expenditures for maintenance and repairs, which do not materially extend the useful lives of assets, are charged to expense as incurred. Upon retirement, sale or other disposition of equipment, the cost and accumulated depreciation are removed from the respective accounts and a gain or loss, if any, is recognized in income/(loss) from operations in the Consolidated Statements of Operations and Comprehensive Loss during the year of disposal. When the Company abandons the anticipated construction of a new solar energy facility during the development phase, costs previously capitalized to development in progress are written off at the parent company. Capitalized Development Cost Capitalized development cost relates to various projects that are under development for the period. As management determines to proceed with the development of a new solar park, or purchase an existing construction project of a solar park, cost toward the final value of that project are recorded in Capitalized Development Cost on the Consolidated Balance Sheet. Cost can include, but are not limited to, financial, technical and legal due diligence costs. As the Company closes either the purchase or development of new solar parks and begins construction in process and then are added to the final asset displayed in Property, and Equipment. If the Company does not close on the prospective project, these costs are written off to Development Cost on the Consolidated Statement Operations and Comprehensive Loss. Impairment of Solar Energy Facilities The Company reviews its investments in property and equipment for impairment whenever events or changes in circumstances indicate that the carrying value of an asset may not be recoverable. Impairment is evaluated at the asset group level, which is determined based upon the lowest level of separately identifiable cash flows. When evaluating for impairment, if the estimated undiscounted cash flows from the use of the asset group are less than the asset group’s carrying amount, then the asset group is deemed to be impaired and is written down to its fair value. Fair value is determined by net realizable value of the assets using ASC 820. The amount of the impairment loss is equal to the excess of the asset group’s carrying value over its estimated fair value During the year ended December 31, 2023, the Company recorded an impairment loss of $11.8 million in the Consolidated Statement of Operations and Comprehensive Loss related to the Polish assets held for sale to reduce the carrying amount of the assets in the disposal group to their fair value less costs to sell. This was recognized in discontinued operations on the Consolidated Statement of Operations and Comprehensive Loss. Deferred Financing Costs and Debt Discount Amortization The Company incurs expenses related to debt arrangements. These deferred financing costs and debt discount costs are capitalized and amortized over the term of the related debt or revolving credit facilities and netted against the related debt. Asset Retirement Obligations In connection with the acquisition or development of solar energy facilities, the Company may have the legal requirement to remove long-lived assets constructed on leased property and to restore the leased property to its condition prior to the construction of the long-lived assets. This legal requirement is referred to as an asset retirement obligation (ARO). If the Company determines that an ARO is required for a specific solar energy facility, the Company records the present value of the estimated future liability when the solar energy facility is placed in service as an ARO liability. The discount rate used to estimate the present value of the expected future cash flows for the year ended December 31, 2023 and 2022 was 7.3% and 7.1% respectively. The Company accretes the ARO liability to its future value over the solar energy facility’s useful life and records the related interest expense to amortization expense on the consolidated statement of operations. Solar facilities that require AROs are recorded as part of the carrying value of property and depreciated over the solar energy facility’s useful life. Leases In February 2016, the FASB established Topic 842, Leases, by issuing Accounting Standards Update (ASU) No. 2016-02, which requires lessees to recognize leases on-balance sheet and disclose key information about leasing arrangements. Topic 842 was subsequently amended by ASU No. 2018-01, Land Easement Practical Expedient for Transition to Topic 842; ASU No. 2018-10, Codification Improvements to Topic 842, Leases; and ASU No. 2018-11, Targeted Improvements. The new standard establishes a right-of-use model (ROU) that requires a lessee to recognize a ROU asset and lease liability on the balance sheet for all leases with a term longer than 12 months. Leases will be classified as finance or operating, with classification affecting the pattern and classification of expense recognition in the income statement. A modified retrospective transition approach is required, applying the new standard to all leases existing at the date of initial application. The Company adopted the new standard on January 1, 2022 and used the effective date as our date of initial application. Consequently, financial information will not be updated and the disclosures required under the new standard will not be provided for dates and periods before January 1, 2022. The new standard provides a number of optional practical expedients in transition. We elected the ‘package of practical expedients’, which permits us not to reassess under the new standard our prior conclusions about lease identification, lease classification and initial direct costs. Upon adoption the company recognized $8.8 million of Right of Use Assets and $8.7 million of associated liabilities. Lease assets and liabilities are recognized based on the present value of the future lease payments over the lease term at the lease commencement date and are presented on the consolidated statements of financial condition. The Company estimates its incremental borrowing rate based on information available at the commencement date in determining the present value of future payments. For additional information, see Footnote 16 - Leases. Operating lease expense attributable to site leases is reported within cost of revenues in the Company’s Statement of Operations and Comprehensive Loss; whereas lease expense attributable to all other operating leases is reported within selling, general, and administrative expense in the Company’s Statement of Operations and Comprehensive Loss. Revenue Recognition The Company follows the guidance of the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 606, Revenue from Contracts with Customers (“ASC 606”). The core principle underlying revenue recognition under ASC 606 is that revenue should be recognized as goods or services are transferred to customers in an amount that reflects the consideration to which the Company expects to be entitled. ASC 606 defines a five-step process to achieve this core principle. ASC 606 also mandates additional disclosure about the nature, amount, timing and uncertainty of revenues and cash flows arising from customer contracts, including significant judgments, and changes in judgments and assets recognized from costs incurred to obtain or fulfill a contract. The Company derives revenues through its subsidiaries from the sale of electricity and the sale of solar renewable energy credits (RECs) in Romania and guarantees of origin certificates (GoOs) in Poland. The Company receives Green Certificates based on the amount of energy produced in Romania. Energy generation revenue and solar renewable energy credits revenue are recognized as electricity generated by the Company’s solar energy facilities is delivered to the grid, at which time all performance obligations have been delivered. Revenues are based on actual output and contractual sale prices set forth its customer contracts. The Company’s current portfolio of renewable energy facilities is generally contracted under long-term Country Renewable Programs (FIT programs) in Italy or Energy Offtake Agreements (PPAs/VPPAs) with creditworthy counterparties in Poland, Romania and the United States. Pricing of the electricity sold under these FITs and PPAs is generally fixed for the duration of the contract, although some of its PPAs have price escalators based on an index (such as the consumer price index) or other rates specified in the applicable PPA. One solar park in the Netherlands receives pre-payments calculated at the beginning of the year and based on the previous years’ production (MWhs produced) multiplied by a calculated average price per MWh for the year and divided by twelve. The Company books revenue monthly by multiplying actual production per the Company’s meters by the average price provided by the Offtaker at the beginning of the year to estimate revenue for the month. There is a true-up performed in June of the following year using actual power produced for the previous year multiplied by the average EPEX price (average actual market price per KWh for the year) less the prepayment for the year. If the true-up calculation is positive, The Offtaker settles with a payment to the Company. If the true-up is negative, the Company settles with a payment to Offtaker. Disaggregated Revenues The following table shows the Company’s revenues disaggregated by country and contract type: Year Ended December 31, Revenue by Country 2023 2022 (in thousands) Italy $ 3,360 $ 3,354 Romania 16,608 13,710 United States 116 25 Total for continuing operations $ 20,084 $ 17,089 Discontinued Operations: Netherlands $ 2,840 $ 1,596 Poland 7,593 10,709 Total for discontinued operations $ 10,433 $ 12,305 Total for the period $ 30,517 $ 29,394 Year Ended December 31, Revenue by Offtake Type 2023 2022 (in thousands) Country Renewable Programs $ 2,972 $ 2,885 Green Certificates 10,548 9,409 Energy Offtake Agreements 6,560 4,795 Other Revenue 4 - Total for continuing operations $ 20,084 $ 17,089 Discontinued Operations: Country Renewable Programs $ 5,499 $ 6,994 Guarantees of Origin 129 44 Energy Offtake Agreements 4,805 5,267 Total for discontinued operations $ 10,433 $ 12,305 Total for the period $ 30,517 $ 29,394 One customer represented 35% of continuing operational revenues during the year ended December 31, 2023 compared to two customers that represented 29% for the year ended December 31, 2022. The revenues from these customers accounted for $11.4 million and $9.7 million of revenue for the year ended December 31, 2023 and 2022 respectively. Two customers represented 34% of the discontinued operational revenues during the year ended December 31, 2023 compared to two customers that represented 42% for the year ended December 31, 2022. The revenues from these customers accounted for $11.2 million and $14.2 million of revenue for the year ended December 31, 2023 and 2022 respectively. Three customers represented 61% of the Company’s continuing operational accounts receivable for the year ended December 31, 2023. One customer represented 23% of the Company’s discontinued operational accounts receivable for the year ended December 31, 2023. The company did not have any customers who represented more than 10% of accounts receivable for the year ended December 31, 2022. Unbilled Energy Incentives Earned The Company derives revenues from the sale of green certificates for the Romania projects. The green certificates revenues are recognized in the month they are generated by the solar project and registered with the local authority. The Company considers them unbilled at the end of the period if they have not been invoiced to a third-party customer. Cost of Revenue Cost of revenue primarily consists of operations and maintenance expense, insurance premiums, property taxes and other miscellaneous costs associated with the operations of solar energy facilities. Costs are charged to expense as incurred. Taxes Recoverable and Payable The Company records taxes recoverable when there has been an overpayment of taxes due to timing of the Value Added Tax (VAT) between vendors and customers. The VAT tax can also be offset against a Country’s income taxes where the VAT was registered. Development Cost Development costs are incurred when the Company abandons the development or acquisition of renewable energy projects. The Company depends heavily on government policies that support our business and enhance the economic feasibility of developing and operating solar energy projects in regions in which we operate or plan to develop and operate renewable energy facilities. The Company can decide to abandon a project if it becomes uneconomic due to various factors, for example, a change in market conditions leading to higher costs of construction, lower energy rates, or other factors that change the expected returns on the project. In addition, political factors or otherwise where governments from time to time may review their laws and policies that support renewable energy and consider actions that would make the laws and policies less conducive to the development and operation of renewable energy facilities. Any reductions or modifications to, or the elimination of, governmental incentives or policies that support renewable energy or the imposition of additional taxes or other assessments on renewable energy, could result in, among other items, the lack of a satisfactory market for the development and/or financing of new renewable energy projects, our abandoning the development of renewable energy projects, a loss of our investments in the projects and reduced project returns, any of which could have a material adverse effect on our business, financial condition, results of operations and prospects. At the time The Company decides to abandon a project, Development Cost are recognized on the Consolidated Statements of Operations and Other Comprehensive Income/(Loss) Risks and Uncertainties The Company’s operations are subject to significant risks and uncertainties including financial, operational, technological, and regulatory risks and the potential risk of business failure. See Note 2 regarding going concern matters. Fair Value of Financial Instruments The Company measures its financial instruments at fair value. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. U.S. GAAP establishes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value into three (3) broad levels. The fair value hierarchy gives the highest priority to quoted prices (unadjusted) in active markets for identical assets or liabilities and the lowest priority to unobservable inputs. The three (3) levels of fair value hierarchy are described below: Level 1 – Quoted market prices available in active markets for identical assets or liabilities as of the reporting date. Level 2 – Pricing inputs other than quoted prices in active markets included in Level 1 that are either directly or indirectly observable as of the reporting date. Inputs are observable, unadjusted quoted prices in active markets for similar assets or liabilities, unadjusted quoted prices for identical or similar assets or liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities. Level 3 – Pricing inputs that are unobservable. Financial assets are considered Level 3 when their fair values are determined using pricing models, discounted cash flow methodologies or similar techniques, and at least one significant model assumption or input is unobservable. The Company holds various financial instruments that are not required to be measured at fair value. For cash and cash equivalents, restricted cash, accounts receivable, various debt instruments, prepayments and other current assets, accounts payable, accrued liabilities and other current liabilities, the carrying value approximated their fair values due to the short-term maturity of these instruments. The Company’s forward purchase agreement asset is considered a Level 3 financial instrument at fair value and is described below (see Note 5). Business Combinations and Acquisition of Assets The Company applies the definition of a business in ASC 805, Business Combinations, When an acquired group of assets does not constitute a business, the transaction is accounted for as an asset acquisition. The cost of assets acquired, and liabilities assumed in asset acquisitions is allocated based upon relative fair value. The fair value measurements of the solar facilities acquired, and asset retirement obligations assumed were derived utilizing an income approach and based, in part, on significant inputs not observable in the market. These inputs include, but are not limited to, estimates of future power generation, commodity prices, operating costs, and appropriate discount rates. These inputs require significant judgments and estimates at the time of the valuation. Transaction costs, including legal and financing fees directly related to the acquisition, incurred are capitalized as a component of the assets acquired. The allocation of the purchase price directly affects the following items in the Company’s consolidated financial statements: ● The amount of purchase price allocated to the various tangible and intangible assets and liabilities on the Company Balance Sheet, ● The amounts allocated to all other tangible assets and intangibles are amortized to depreciation or amortization expense, with the exception of favorable and unfavorable rate land leases and unfavorable rate Operation and Maintenance (O&M) contracts which are amortized to cost of revenue; and The period of time over which tangible and intangible assets and liabilities are depreciated or amortized varies, and thus, changes in the amounts allocated to these assets and liabilities will have a direct impact on the Company’s results of operations. Income Taxes Deferred taxes are determined using the asset and liability method; whereby, deferred tax assets are recognized for deductible temporary differences, operating loss and tax credit carry forwards, and deferred tax liabilities are recognized for taxable temporary differences. Temporary differences are the differences between the reported amounts of assets and liabilities and their tax basis. Valuation allowances are established when necessary to reduce deferred tax assets to the amount expected to be realized. Deferred tax assets and liabilities are adjusted for the effects of changes in tax laws and rates on the date of enactment. The Company evaluated the provisions of ASC 740 related to the accounting for uncertainty in income taxes recognized in the financial statements. ASC 740 prescribes a comprehensive model for how a company should recognize, present, and disclose uncertain positions that the company has taken or expects to take in its return. For those benefits to be recognized, a tax position must be more-likely-than-not to be sustained upon examination by taxing authorities. Differences between the positions taken or expected to be taken in a tax return and the benefit recognized and measured pursuant to the interpretation are referred to as “unrecognized benefits”. A liability is recognized for an unrecognized tax benefit because it represents an enterprise’s potential future obligation to the taxing-authority for a tax position that was not recognized as a result of applying the provisions of ASC 740. As a result of the Tax Cuts and Jobs Act (TCJA) of 2017, the Company analyzed if a liability needed to be recorded for the deemed repatriation of undistributed earnings. It was determined that there is no outstanding liability associated with this based on overall negative undistributed earnings (accumulated deficit) in the consolidated foreign group. An additional provision of the TCJA is the implementation of the Global Intangible-Low Taxed Income Tax, or “GILTI.” The Company has elected to account for the impact of GILTI in the period in which the tax actually applies to the Company. Penalties and interest assessed by income tax authorities would be included in income tax expense. For the period ended December 31, 2023, the Company did not incur any penalties or interest. Stock-Based Compensation The Company accounts for stock-based compensation in accordance with ASC 718. Stock-based compensation expense for equity instruments issued to employees and non-employees is measured based on the grant-date fair value of the awards. The fair value of each stock unit is determined based on the valuation of the Company’s stock on the date of grant. The fair value of each stock option is estimated on the date of grant using the Black-Scholes-Merton stock option pricing valuation model. The Company uses the simplified method for calculating the expected term of their options. The Company recognizes compensation costs using the straight-line method for equity compensation awards over the requisite service period of the awards, which is generally the awards’ vesting period. The Company accounts for forfeitures of awards in the period they occur. Use of the Black-Scholes-Merton option-pricing model requires the input of highly subjective assumptions, including (1) the expected terms of the option, (2) the expected volatility of the price of the Company’s common stock, and (3) the expected dividend yield of our common stock. The assumptions used in the option-pricing model represent management’s best estimates. These estimates involve inherent uncertainties and the application of management’s judgments. If factors change and different assumptions are used, the Company’s stock-based compensation expense could be materially different in the future. Additional inputs to the Black-Scholes-Merton option-pricing model include the risk-free interest rate and the fair value of the Company’s common stock. The Company determines the risk-free interest rate by using the U.S. Treasury Rates of the same period as the expected term of the stock-option. Net Loss Per Share Net loss per share is computed pursuant to ASC 260, Earnings per Share Year Ended December 31, 2023 2022 (in thousands) Warrants 12,345 11,945 Total 12,345 11,945 Foreign Currency Transactions and Other Comprehensive Loss Foreign currency transactions are those transactions whose terms are denominated in a currency other than the currency of the primary economic environment in which the Company operates, which is referred to as the functional currency. The functional currency of the Company’s foreign subsidiaries is typically the applicable local currency which is Romanian Lei (RON), Polish Zloty (PLN) or European Union Euros (EUR). Transactions denominated in foreign currencies are remeasured to the functional currency using the exchange rate prevailing at the balance sheet date for balance sheet accounts and using an average exchange rate during the period, which approximates the daily exchange rate, for income statement accounts. Foreign currency gains or losses resulting from such remeasurement are included in the Consolidated Statement of Operations in the period in which they arise. Transaction gains and losses are recognized in the Company’s Results of Operations based on the difference between the foreign exchange rates on the transaction date and on the reporting date. The Company had an immaterial net foreign exchange loss for the year ended December 31, 2023 and 2022. The translation from functional foreign currency to United States Dollars (U.S. Dollar) is performed for balance sheet accounts using current exchange rates in effect at the balance sheet date and using an average exchange rate during the period, which approximates the daily exchange rate, for income statement accounts. The effects of translating financial statements from functional currency to reporting currency are recorded in other comprehensive income. For the years ended December 31, 2023 and 2022, the increase/(decrease) in comprehensive loss related to foreign currency translation gains was $0.7 million and ($1.0) million, respectively. Recently Adopted Accounting Pronouncements In June 2016, the F

Business Combination

Business Combination	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Business Combination [Abstract]
Business Combination	4. Business Combination As discussed in Note 1 – Organization and Formation, on December 22, 2023, Clean Earth Acquisitions Corp. (“CLIN”), Alternus Energy Group Plc (“AEG”) and Clean Earth Acquisition Sponsor LLC (the “Sponsor”) completed the Business Combination. Upon the Closing of the Business Combination, the following occurred: ● In connection with the Business Combination, AEG transferred to CLIN all issued and outstanding AEG interests in certain of its subsidiaries (the “Acquired Subsidiaries”) in exchange for the issuance by CLIN at the Closing of 57,500,000 shares of common stock of CLIN. At Closing, CLIN changed its name to Alternus Clean Energy, Inc. (“ALCE” or the “Company”). ● In connection with the Business Combination, 23,000,000 rights to receive one-tenth (1/10) of one share of Class A common stock was exchanged for 2,300,000 shares of the Company’s common stock. ● In addition to shares issued to AEG noted above, 225,000 shares of Common Stock were issued at Closing to the Sponsor to settle a CLIN convertible promissory note held by the Sponsor at Closing. ● Each share of CLIN Class A common stock held by the CLIN Sponsor prior to the closing of the Business Combination, which totaled 8,556,667 shares, was exchanged for, on a one-for-one basis for shares of the Company’s Common Stock. ● Each share of CLIN common stock subject to possible redemption that was not redeemed prior to the closing of the Business Combination, which totaled 127,142 shares, was exchanged for, on a one-for-one basis for shares of the Company’s Common Stock. ● In connection with the Business Combination, an investor that provided the Company funding through a promissory note, was due to receive warrants to purchase 300,000 shares of Common Stock at an exercise price of $0.01 per share and warrants to purchase 100,000 shares of Common Stock at an exercise price of $11.50 per share pursuant to the Secured Promissory Note Agreement dated October 3, 2023. Upon closing of the Business Combination, the investor received those warrants. ● In connection with the Business Combination, CLIN entered into a Forward Purchase Agreement (the “FPA”) with certain accredited investors (the “FPA Investors”) that gave the FPA Investors the right, but not an obligation, to purchase up to 2,796,554 shares of CLIN’s common stock. Of the 2,796,554 shares, the FPA Investors purchased 1,300,320 shares of Common Stock and the Company issued an aggregate of 1,496,234 shares of the Company’s common stock pursuant to the FPA. ● The proceeds received by the Company from the Business Combination, net of the FPA and transaction costs, totaled $5.1 million. The following table presents the total Common Stock outstanding immediately after the closing of the Business Combination: Number of Exchange of CLIN common stock subject to possible redemption that was not redeemed for Alternus Clean Energy Inc. common stock 127,142 Exchange of public share rights held by CLIN shareholders for Alternus Clean Energy Inc. common stock 2,300,000 Issuance of Alternus Clean Energy, Inc. common stock to promissory note holders 400,000 Exchange of CLIN Class A common stock held by CLIN Sponsor for Alternus Clean Energy Inc. common stock 8,556,667 Subtotal - Business Combination, net of redemptions 11,383,809 Issuance of shares under the FPA 1,496,234 Shares purchased by the accredited investor under the FPA 1,300,320 Issuance of Alternus Clean Energy Inc. common stock to Alternus Energy Group Plc. on the Closing Date 57,500,000 Issuance of Alternus Clean Energy Inc. common stock to the CLIN Sponsor as a holder of CLIN convertible notes on the Closing Date 225,000 Total – Alternus Clean Energy Inc. common stock outstanding as a result of the Business Combination, FPA, exchange of Acquired Subsidiaries’ shares for shares of Alternus Clean Energy Inc. and issuance of Alternus Clean Energy Inc. common stock the holder of CLIN convertible notes. 71,905,363	4. Business Combination As discussed in Note 1 – Organization and Formation, on December 22, 2023, Clean Earth Acquisitions Corp. (“CLIN”), Alternus Energy Group Plc (“AEG”) and Clean Earth Acquisition Sponsor LLC (the “Sponsor”) completed the Business Combination. Upon the Closing of the Business Combination, the following occurred: ● In connection with the Business Combination, AEG transferred to CLIN all issued and outstanding AEG interests in certain of its subsidiaries (the “Acquired Subsidiaries”) in exchange for the issuance by CLIN at the Closing of 57,500,000 shares of common stock of CLIN. At Closing, CLIN changed its name to Alternus Clean Energy, Inc. (“ALCE” or the “Company”). ● In connection with the Business Combination, 23,000,000 rights to receive one-tenth (1/10) of one share of Class A common stock was exchanged for 2,300,000 shares of the Company’s common stock. ● In addition to shares issued to AEG noted above, 225,000 shares of Common Stock were issued at Closing to the Sponsor to settle a CLIN convertible promissory note held by the Sponsor at Closing. ● Each share of CLIN Class A common stock held by the CLIN Sponsor prior to the closing of the Business Combination, which totaled 8,556,667 shares, was exchanged for, on a one-for-one basis for shares of the Company’s Common Stock. ● Each share of CLIN common stock subject to possible redemption that was not redeemed prior to the closing of the Business Combination, which totaled 127,142 shares, was exchanged for, on a one-for-one basis for shares of the Company’s Common Stock. ● In connection with the Business Combination, an investor that provided the Company funding through a promissory note, was due to receive warrants to purchase 300,000 shares of Common Stock at an exercise price of $0.01 per share and warrants to purchase 100,000 shares of Common Stock at an exercise price of $11.50 per share pursuant to the Secured Promissory Note Agreement dated October 3, 2023. Upon closing of the Business Combination, the investor received those warrants. ● In connection with the Business Combination, CLIN entered into a Forward Purchase Agreement (the “FPA”) with certain accredited investors (the “FPA Investors”) that gave the FPA Investors the right, but not an obligation, to purchase up to 2,796,554 shares of CLIN’s common stock. Of the 2,796,554 shares, the FPA Investors purchased 1,300,320 shares of Common Stock and the Company issued an aggregate of 1,496,234 shares of the Company’s common stock pursuant to the FPA. ● The proceeds received by the Company from the Business Combination, net of the FPA and transaction costs, totaled $5.1 million. The following table presents the total Common Stock outstanding immediately after the closing of the Business Combination: Number of Exchange of CLIN common stock subject to possible redemption that was not redeemed for Alternus Clean Energy Inc. common stock 127,142 Exchange of public share rights held by CLIN shareholders for Alternus Clean Energy Inc. common stock 2,300,000 Issuance of Alternus Clean Energy, Inc. common stock to promissory note holders 400,000 Exchange of CLIN Class A common stock held by CLIN Sponsor for Alternus Clean Energy Inc. common stock 8,556,667 Subtotal - Business Combination, net of redemptions 11,383,809 Issuance of shares under the FPA 1,496,234 Shares purchased by the accredited investor under the FPA 1,300,320 Issuance of Alternus Clean Energy Inc. common stock to Alternus Energy Group Plc. on the Closing Date 57,500,000 Issuance of Alternus Clean Energy Inc. common stock to the CLIN Sponsor as a holder of CLIN convertible notes on the Closing Date 225,000 Total – Alternus Clean Energy Inc. common stock outstanding as a result of the Business Combination, FPA, exchange of Acquired Subsidiaries’ shares for shares of Alternus Clean Energy Inc. and issuance of Alternus Clean Energy Inc. common stock the holder of CLIN convertible notes. 71,905,363

Fair Value Measurements

Fair Value Measurements	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Fair Value Measurements [Abstract]
Fair Value Measurements	5. Fair Value Measurements Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants at the measurement date. Inputs used to measure fair value are prioritized within a three-level fair value hierarchy. This hierarchy requires entities to maximize the use of observable inputs and minimize the use of unobservable inputs. The three levels of inputs used to measure fair value are as follows: Level 1 — Quoted prices in active markets for identical assets or liabilities. Level 2 — Observable inputs other than quoted prices included in Level 1, such as quoted prices for similar assets and liabilities in active markets; quoted prices for identical or similar assets and liabilities in markets that are not active; or other inputs that are observable or can be corroborated by observable market data. Level 3 — Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. This includes certain pricing models, discounted cash flow methodologies and similar techniques that use significant unobservable inputs. On December 3, 2023, the Company entered into an agreement with (i) Meteora Capital Partners, LP, (ii) Meteora Select Trading Opportunities Master, LP, and (iii) Meteora Strategic Capital, LLC (collectively “Meteora”) for OTC Equity Prepaid Forward Transactions (the “FPA”). The purpose of the FPA was to decrease the amount of redemptions in connection with the Company’s Special Meeting and potentially increase the working capital available to the Company following the Business Combination. Pursuant to the terms of the FPA, Meteora purchased 2,796,554 (the “Purchased Amount”) shares of common stock concurrently with the Business Combination Closing pursuant to Meteora’s FPA Funding Amount PIPE Subscription Agreement, less the 1,300,320 shares of common stock separately purchased from third parties through a broker in the open market (“Recycled Shares”). Following the consummation of the Business Combination, Meteora delivered a Pricing Date Notice dated December 10, 2023 which included 1,300,320 Recycled Shares, 1,496,234 additional shares and 2,796,554 total number of shares. The FPA provides for a prepayment shortfall in an amount in U.S. dollars equal to $500,000. Meteora in its sole discretion may sell Recycled Shares at any time following the Trade Date at prices (i) at or above $10.00 during the first three months following the Closing Date and (ii) at any sales price thereafter, without payment by Meteora of any Early Termination Obligation until such time as the proceeds from such sales equal 100% of the Prepayment Shortfall The number of shares subject to the Forward Purchase Agreement is subject to reduction following a termination of the FPA with respect to such shares as described under “Optional Early Termination” in the FPA. The reset price is set at $10.00. Commencing June 22, 2024 the reset price will be subject to reduction upon the occurrence of a Dilutive Offering. The Company holds various financial instruments that are not required to be recorded at fair value. For cash, restricted cash, accounts receivable, accounts payable, and short-term debt the carrying amounts approximate fair value due to the short maturity of these instruments. The fair value of the Company’s recorded forward purchase agreement (“FPA”) is determined based on unobservable inputs that are not corroborated by market data, which require a Level 3 classification. A Monte Carlo simulation model was used to determine the fair value. The Company records the forward purchase agreement at fair value on the consolidated balance sheets with changes in fair value recorded in the consolidated statements of operation. As of March 31, 2024, the Forward Purchase Agreement value was $0, as presented below: Fair Value Measurement Level 1 Level 2 Level 3 Total Forward Purchase Agreement - - - - Total $ - $ - $ - $ - The following table presents changes of the forward purchase agreement with significant unobservable inputs (Level 3) as of March 31, 2024, in thousand: Forward Purchase Agreement Balance at January 1, 2023 $ - Recognition of Forward Purchase Agreement Asset 17,125 Change in fair value (16,642 ) Balance at December 31, 2023 483 Change in fair value (483 ) Balance at March 31, 2024 $ - The Company measures the forward purchase agreement using a Monte Carlo simulation valuation model using the following assumptions: Forward Purchase Agreement Risk-free rate 4.5 % Underlying stock price $ 0.43 Expected volatility 92.7 % Term 2.73 years Dividend yield 0 %	5. Fair Value Measurements Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants at the measurement date. Inputs used to measure fair value are prioritized within a three-level fair value hierarchy. This hierarchy requires entities to maximize the use of observable inputs and minimize the use of unobservable inputs. The three levels of inputs used to measure fair value are as follows: Level 1 — Quoted prices in active markets for identical assets or liabilities. Level 2 — Observable inputs other than quoted prices included in Level 1, such as quoted prices for similar assets and liabilities in active markets; quoted prices for identical or similar assets and liabilities in markets that are not active; or other inputs that are observable or can be corroborated by observable market data. Level 3 — Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. This includes certain pricing models, discounted cash flow methodologies and similar techniques that use significant unobservable inputs. On December 3, 2023, the Company entered into an agreement with (i) Meteora Capital Partners, LP, (ii) Meteora Select Trading Opportunities Master, LP, and (iii) Meteora Strategic Capital, LLC (collectively “Meteora”) for OTC Equity Prepaid Forward Transactions (the “FPA”). The purpose of the FPA was to decrease the amount of redemptions in connection with the Company’s Special Meeting and potentially increase the working capital available to the Company following the Business Combination. Pursuant to the terms of the FPA, Meteora purchased 2,796,554 (the “Purchased Amount”) shares of common stock concurrently with the Business Combination Closing pursuant to Meteora’s FPA Funding Amount PIPE Subscription Agreement, less the 1,300,320 shares of common stock separately purchased from third parties through a broker in the open market (“Recycled Shares”). Following the consummation of the Business Combination, Meteora delivered a Pricing Date Notice dated December 10, 2023 which included 1,300,320 Recycled Shares, 1,496,234 additional shares and 2,796,554 total number of shares. The FPA provides for a prepayment shortfall in an amount in U.S. dollars equal to $500,000. Meteora in its sole discretion may sell Recycled Shares at any time following the Trade Date at prices (i) at or above $10.00 during the first three months following the Closing Date and (ii) at any sales price thereafter, without payment by Meteora of any Early Termination Obligation until such time as the proceeds from such sales equal 100% of the Prepayment Shortfall The number of shares subject to the Forward Purchase Agreement is subject to reduction following a termination of the FPA with respect to such shares as described under “Optional Early Termination” in the FPA. The reset price is set at $10.00. Commencing June 22, 2024 the reset price will be subject to reduction upon the occurrence of a Dilutive Offering. The Company holds various financial instruments that are not required to be recorded at fair value. For cash, restricted cash, accounts receivable, accounts payable, and short-term debt the carrying amounts approximate fair value due to the short maturity of these instruments. The fair value of the Company’s recorded forward purchase agreement (“FPA”) is determined based on unobservable inputs that are not corroborated by market data, which require a Level 3 classification. A Monte Carlo simulation model was used to determine the fair value. The Company records the forward purchase agreement at fair value on the consolidated balance sheets with changes in fair value recorded in the consolidated statements of operation. The following table presents balances of the forward purchase agreement with significant unobservable inputs (Level 3) as of December 31, 2023, in thousand: Fair Value Measurement Level 1 Level 2 Level 3 Total Forward Purchase Agreement - - 483 483 Total $ - $ - $ 483 $ 483 The following table presents changes of the forward purchase agreement with significant unobservable inputs (Level 3) for the year ended December 31, 2023, in thousand: Forward Purchase Agreement Asset Balance at January 1, 2023 $ - Recognition of Forward Purchase Agreement Asset 17,125 Change in fair value (16,642 ) Balance at December 31, 2023 $ 483 The Company measures the forward purchase agreement using a Monte Carlo simulation valuation model using the following assumptions: Forward Purchase Agreement Asset Rik-free rate 4% Underlying stock price $1.50 Expected volatility 75% Term 2.98 years Dividend yield 0%

Business Combination and Acquis

Business Combination and Acquisitions of Assets	12 Months Ended
	Dec. 31, 2023
Business Combination and Acquisitions of Assets [Abstract]
Business Combination and Acquisitions of Assets	6. Business Combination and Acquisitions of Assets The Company applies the definition of a business in ASC 805, Business Combinations Acquisition of RA01 Sp. Z.O.O. On March 24, 2022, the Company acquired a solar park portfolio located in Poland from a third party for a total purchase price, net of cash received, of $1.1 million. The transaction was accounted for as an acquisition of assets, whereby the Company acquired $1.0 million of property and equipment and $0.1 million of other assets. These assets have been moved to discontinued operations as of December 31, 2023. Refer to Footnote 20 for more details. Acquisition of Gardno Sp. Z.O.O. On March 24, 2022, the Company acquired a solar park portfolio located in Poland from a third party for a total purchase price, net of cash received, of $6.6 million. The transaction was accounted for as an acquisition of assets, whereby the Company acquired $6.4 million of property and equipment, and $0.2 million of other assets. These assets have been moved to discontinued operations as of December 31, 2023. Refer to Footnote 20 for more details. Acquisition of Gardno 2 Sp. Z.O.O. On March 24, 2022, the Company acquired a solar park portfolio located in Poland from a third party for a total purchase price, net of cash received, of $4.4 million. The transaction was accounted for as an acquisition of assets, whereby the Company acquired $4.3 million of property and equipment, and $0.1 million of other assets. These assets have been moved to discontinued operations as of December 31, 2023. Refer to Footnote 20 for more details.

Accounts Receivable

Accounts Receivable	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Accounts Receivable [Abstract]
Accounts Receivable	6. Accounts Receivable Accounts receivable relate to amounts due from customers for services that have been performed and invoices that have been sent. Unbilled energy incentives relate to services that have been performed for the customer but have yet to be invoiced. Accounts receivables and unbilled energy incentives consist of the following (in thousands): March 31 December 31 2024 2023 (in thousands) Accounts receivable $ 2,119 $ 651 Unbilled energy incentives earned 6,048 5,607 Total $ 8,167 $ 6,258	7. Accounts Receivable Accounts receivable relate to amounts due from customers for services that have been performed and invoices that have been sent. Unbilled energy incentives relate to services that have been performed for the customer but have yet to be invoiced. Accounts receivables, and unbilled energy incentives consist of the following (in thousands): Year Ended December 31, 2023 2022 (in thousands) Accounts receivable $ 651 $ 3,335 Unbilled energy incentives earned 5,607 4,954 Total $ 6,258 $ 8,289

Prepaid Expenses and Other Curr

Prepaid Expenses and Other Current Assets	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Prepaid Expenses and Other Current Assets [Abstract]
Prepaid Expenses and Other Current Assets	7. Prepaid Expenses and Other Current Assets Prepaid and other current expenses generally consist of amounts paid to vendors for services that have not yet been performed. Other receivable, prepaid expenses, and other current assets consist of the following (in thousands): March 31 December 31 2024 2023 (in thousands) Prepaid expenses and other current assets $ 2,501 $ 2,602 Accrued revenue - 6 Other receivable 522 736 Total $ 3,023 $ 3,344	8. Prepaid Expenses and Other Current Assets Prepaid and other current expenses generally consist of amounts paid to vendors for services that have not yet been performed. Other receivable, prepaid expenses and other current assets consist of the following (in thousands): Year Ended December 31, 2023 2022 (in thousands) Prepaid expenses and other current assets $ 2,602 $ 328 Accrued revenue 6 294 Other receivable 736 860 Total $ 3,344 $ 1,482

Property and Equipment, Net

Property and Equipment, Net	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Property and Equipment, Net [Abstract]
Property and Equipment, Net	8. Property and Equipment, Net The components of property and equipment, net were as follows at March 31, 2024 and December 31, 2023 (in thousands): March 31 December 31 2024 2023 (in thousands) Solar energy facilities $ 55,737 $ 55,318 Land 500 511 Software and computers 6 - Furniture and fixtures 207 210 Asset retirement 164 168 Construction in progress 12,705 12,421 Total property and equipment 69,319 68,628 Less: Accumulated depreciation (7,714 ) (7,326 ) Total $ 61,605 $ 61,302	9. Property and Equipment, Net The components of property and equipment, net were as follows at December 31 (in thousands): Year Ended December 31, 2023 2022 (in thousands) Solar energy facilities $ 55,318 $ 75,009 Building - 107 Land 511 497 Furniture and fixtures 210 49 Asset retirement 168 341 Construction in progress 12,421 3,093 Total property and equipment 68,628 79,096 Less: Accumulated depreciation (7,326 ) (10,143 ) Total $ 61,302 $ 68,953 There was $5.1 million transferred from construction in progress to solar energy facilities during the twelve-month period through December 31, 2023 and $0.6 million during the twelve-month period through December 31, 2022.

Capitalized Development Cost an

Capitalized Development Cost and Other Long-Term Assets	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Capitalized Development Cost and Other Long-Term Assets [Abstract]
Capitalized development cost and other long-term assets	9. Capitalized development cost and other long-term assets Capitalized development costs are amounts paid to vendors that are related to the purchase and construction of solar energy facilities. Notes receivable and prepaids consist of amounts owed to the Company as well as amounts paid to vendors for services that have yet to be received by the Company. Capitalized cost and other long-term assets consisted of the following (in thousands): March 31 December 31 2024 2023 (in thousands) Capitalized development cost $ 6,351 $ 6,216 Other receivables 1,000 1,483 Total $ 7,351 $ 7,699 Capitalized development cost relates to various projects that are under development for the period. As the Company closes either a purchase or development of new solar parks, these development costs are added to the final asset displayed in Property and Equipment. If the Company does not close on the prospective project, these costs are written off to Development Cost on the Consolidated Statement Operations and Comprehensive Loss. Capitalized Development Cost consist of $2.1 million of active development in the U.S. and $4.3 million across Europe. Other Receivables as of March 31, 2024 relates to a security deposit of $1.0 million in relation to the Power Purchase Agreement for a development project in Tennessee.	10. Capitalized development cost and other long-term assets Capitalized development costs are amounts paid to vendors that are related to the purchase and construction of solar energy facilities. Notes receivable and prepaids consist of amounts owed to the Company as well as amounts paid to vendors for services that have yet to be received by the Company. Capitalized cost and other long-term assets consisted of the following (in thousands): Year Ended December 31, 2023 2022 (in thousands) Capitalized development cost $ 6,216 $ 2,146 Other receivables 1,483 - Total $ 7,699 $ 2,146 Capitalized development cost relates to various projects that are under development for the period. As the Company closes either a purchase or development of new solar parks, these development costs are added to the final asset displayed in Property, and Equipment. If the Company does not close on the prospective project, these costs are written off to Development Cost on the Consolidated Statement Operations and Comprehensive Loss. Capitalized Development Cost consist of $2.1 million of active development in the U.S. and $4.1 million across Europe. Other Receivables relates to, security deposits of $1.0 million in relation to the Power Purchase Agreement for a development project in Tennessee and $483 thousand related to the Forward Purchase Agreement.

Accounts Payable

Accounts Payable	12 Months Ended
	Dec. 31, 2023
Accounts Payable [Abstract]
Accounts Payable	11. Accounts Payable Accounts payable represent amounts owed to suppliers of goods and services that the Group has consumed through operations. Accounts payable consist of the following (in thousands): Year Ended December 31, 2023 2022 (in thousands) Accounts payable $ 5,084 $ 1,138 Total $ 5,084 $ 1,138

Deferred Income

Deferred Income	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Deferred Income [Abstarct]
Deferred Income	10. Deferred Income Deferred income relates to income related to Green Certificates from Romania that have been received but not sold. Deferred income consists of the following (in thousands): Activity Deferred income – Balance January 1, 2023 $ 4,954 Green certificates received 10,663 Green certificates sold (10,169 ) Foreign exchange gain/(loss) 159 Deferred income – Balance December 1, 2023 $ 5,607 Green certificates received 2,030 Green certificates sold (1,468 ) Foreign exchange gain/(loss) (121 ) Deferred income – Balance March 31, 2024 $ 6,048	12. Deferred Income Deferred income relates to income related to Green Certificates from Romania that have been received but not sold. Deferred income consists of the following (in thousands): Activity Deferred income – Balance January 1, 2022 $ 3,139 Green certificates received 10,729 Green certificates sold (8,849 ) Foreign exchange gain/(loss) (65 ) Deferred income – Balance December 1, 2022 $ 4,954 Green certificates received 10,663 Green certificates sold (10,169 ) Foreign exchange gain/(loss) 159 Deferred income – Balance December 31, 2023 $ 5,607

Accrued Liabilities

Accrued Liabilities	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Accrued Liabilities [Abstract]
Accrued Liabilities	11. Accrued Liabilities Accrued expenses relate to various accruals for the Company. Accrued interest represents the interest in debt not paid in the three months ended March 31, 2024 and in the year ended December 31, 2023. Accrued liabilities consist of the following (in thousands): March 31 December 31 2024 2023 (in thousands) Accrued legal $ 7,258 $ 8,684 Accrued interest 6,294 5,516 Accrued financing cost 2,397 3,537 Accrued construction expense 363 2,134 Accrued transaction cost - business combination 261 1,527 Accrued audit fees 150 800 Accrued payroll 215 148 Other accrued expenses 2,094 2,064 Total $ 19,032 $ 24,410	13. Accrued Liabilities Accrued expenses relate to various accruals for the Company. Accrued interest represents the interest in debt not paid in the year ended December 31, 2023 and 2022. Accrued liabilities consist of the following (in thousands): Year Ended December 31, 2023 2022 (in thousands) Accrued legal $ 8,684 $ - Accrued interest 5,516 1,992 Accrued financing cost 3,537 - Accrued construction expense 2,134 - Accrued transaction cost - business combination 1,527 - Accrued audit fees 800 - Accrued payroll 148 501 Other accrued expenses 2,064 978 Total $ 24,410 $ 3,471

Taxes Recoverable and Payable

Taxes Recoverable and Payable	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Taxes Recoverable and Payable [Abstract]
Taxes Recoverable and Payable	12. Taxes Recoverable and Payable Taxes recoverable and payable consist of VAT taxes payable and receivable from various European governments through group transactions in these countries. Taxes recoverable consist of the following (in thousands): March 31 December 31 2024 2023 (in thousands) Taxes recoverable $ 683 $ 631 Less: Taxes payable (13 ) (14 ) Total $ 670 $ 617	14. Taxes Recoverable and Payable Taxes recoverable and payable consist of VAT taxes payable and receivable from various European governments through group transactions in these countries. Taxes recoverable consist of the following (in thousands): Year Ended December 31, 2023 2022 (in thousands) Taxes recoverable $ 631 $ 1,388 Less: Taxes payable (14 ) (616 ) Total $ 617 $ 772

Green Bonds, Convertible and No

Green Bonds, Convertible and Non-convertible Promissory Notes	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Green Bonds, Convertible and Non-convertible Promissory Notes [Abstract]
Green Bonds, Convertible and Non-convertible Promissory Notes	13. Green Bonds, Convertible and Non-convertible Promissory Notes The following table reflects the total debt balances of the Company as March 31, 2024 and December 31, 2023 (in thousands): As of As of 2024 2023 (in thousands) Senior Secured Green Bonds $ 87,264 $ 166,122 Senior Secured debt and promissory notes secured 31,523 32,312 Total debt 118,787 198,434 Less current maturities (118,787 ) (198,434 ) Long term debt, net of current maturities $ - $ - Current Maturities $ 118,787 $ 198,434 Less current debt discount (908 ) (892 ) Current Maturities net of debt discount $ 117,879 $ 197,542 The Company incurred debt issuance costs of $0.9 million during the three month period ended March 31, 2024. Debt issuance costs are recorded as a debt discount and are amortized to interest expense over the life of the debt, upon the close of the related debt transaction, in the Consolidated Balance Sheet. Interest expense stemming from amortization of debt discounts for continuing operations for the three months ended March 31, 2024 was $0.7 million and for the year ended December 31, 2023 was $4.9 million. There was no interest expense stemming from amortization of debt discounts for discontinued operations for the three months ended March 31, 2024 and 2023, respectively. All outstanding debt for the company is considered short-term based on their respective maturity dates and are to be repaid within the year 2024. Senior secured debt: In May 2022, AEG MH02 entered into a loan agreement with a group of private lenders of approximately $10.8 million with an initial stated interest rate of 8% and a maturity date of May 31, 2023. In February 2023, the loan agreement was amended stating a new interest rate of 16% retroactive to the date of the first draw in June 2022. In May 2023, the loan was extended and the interest rate was revised to 18% from June 1, 2023. In July 2023, the loan agreement was further extended to October 31, 2023. In November 2023, the loan agreement was further extended to May 31, 2024. Due to these addendums, $0.9 million of interest was recognized in the three months ended March 31, 2024. The Company had principal outstanding of $10.8 million and $11.0 million as of March 31, 2024 and December 31, 2023, respectively. In June 2022, Alt US 02, a subsidiary of Alternus Energy Americas, and indirect wholly owned subsidiary of the Company, entered into an agreement as part of the transaction with Lightwave Renewables, LLC to acquire rights to develop a solar park in Tennessee. The Company entered into a construction promissory note of $5.9 million with a variable interest rate of prime plus 2.5% and an original maturity date of June 29, 2023. On January 26, 2024 the loan was extended to June 29, 2024 due to logistical issues that caused construction delays. The Company had principal outstanding of $5.4 million and $4.3 million as of March 31, 2024 and December 31, 2023, respectively. On February 28, 2023, Alt US 03, a subsidiary of Alternus Energy Americas, and indirect wholly owned subsidiary of the Company, entered into an agreement as part of the transaction to acquire rights to develop a solar park in Tennessee. Alt US 03 entered into a construction promissory note of $920 thousand with a variable interest rate of prime plus 2.5% and due May 31, 2024. This note had a principal outstanding balance of $717 thousand as of March 31, 2024 and December 31, 2023, respectively. In July 2023, one of the Company’s US subsidiaries acquired a 32 MWp solar PV project in Tennessee for $2.4 million financed through a bank loan having a six-month term, 24% APY, and an extended maturity date of February 29, 2024. The project is expected to start operating in Q1 2025. 100% of offtake is already secured by 30-year power purchase agreements with two regional utilities. The Company had a principal outstanding balance of $7.0 million as of March 31, 2024 and December 31, 2023, respectively. As of the date of this report this loan is currently in default, but management is in active discussions with the lender to renegotiate the terms. In July 2023, Alt Spain Holdco, one of the Company’s Spanish subsidiaries acquired the project rights for a 32 MWp portfolio of Solar PV projects in Valencia, Spain, with an initial payment of $1.9 million, financed through a bank loan having a six-month term and accruing ’Six Month Euribor’ plus 2% margin, currently 5.9% interest. On January 24, 2024, the maturity date was extended to July 28, 2024. The portfolio consists of six projects totaling 24.4 MWp. This note had a principal outstanding balance of $3.2 million as of March 31, 2024 and December 31, 2023, respectively. In October 2023, Alternus Energy Americas, one of the Company’s US subsidiaries secured a working capital loan in the amount of $3.2 million with a 0% interest until a specified date and a maturity date of March 31, 2024. In February 2024, the loan was further extended to February 28, 2025 and the principal amount was increased to $3.6 million. In March 2024, the Company began accruing interest at a rate of 10%. Additionally, the Company issued the noteholder warrants to purchase up to 90,000 shares of restricted common stock, exercisable at $0.01 per share having a 5 year term and fair value of $86 thousand. The Company had a principal outstanding balance of $1.8 million as of March 31, 2024 and $3.2 million as of December 31, 2023. As of the date of this report this loan is currently in default, but management is in active discussions with the lender to renegotiate the terms and expects a resolution in a timely manner. In December 2023, Alt US 07, one of the Company’s US subsidiaries acquired the project rights to a 14 MWp solar PV project in Alabama for $1.1 million financed through a bank loan having a six-month term, 24% APY, and a maturity date of May 28, 2024. The project is expected to start operating in Q2 2025. 100% of offtake is already secured by 30-year power purchase agreements with two regional utilities. This note had a principal outstanding balance of $1.1 million as of March 31, 2024 and December 31, 2023, respectively. For the year ended December 31, 2023, 225,000 shares of Common Stock were issued at Closing to the Sponsor of Clean Earth to settle CLIN promissory notes of $1.6 million. The note has a 0% interest rate until perpetuity. The shares were issued at the closing price of $5 per share for $1.1 million. The difference of $0.5 million was recognized as an addition to Additional Paid in Capital. The Company had a principal outstanding balance of $1.4 million as of March 31, 2024 and $1.6 million as of December 31, 2023. Management determined the extinguishment of this note is the result of a Troubled Debt Restructuring. Convertible Promissory Notes: In January 2024, the Company assumed a $938 thousand (€850 thousand) convertible promissory note from AEG PLC, a related party. The note had a 10% interest maturing in March 2025. The note was assumed as part of the Business Combination that was completed in December 2023. On January 3, 2024, the noteholder converted all of the principal and accrued interest owed under the note, equal to $1.0 million, into 1,320,000 shares of restricted common stock. Other Debt: In January 2021, the Company approved the issuance by one of its subsidiaries, Solis, of a series of 3-year senior secured green bonds in the maximum amount of $242.0 million (€200.0 million) with a stated coupon rate of 6.5% + EURIBOR and quarterly interest payments. The bond agreement is for repaying existing facilities of approximately $40.0 million (€33 million), and funding acquisitions of approximately $87.2 million (€72.0 million). The bonds are secured by the Solis Bond Company’s underlying assets. The Company raised approximately $125.0 million (€110.0 million) in the initial funding. In November 2021, Solis Bond Company DAC, completed an additional issue of $24.0 million (€20.0 million). The additional issue was completed at an issue price of 102% of par value, corresponding to a yield of 5.5%. The Company raised $11.1 million (€10.0 million) in March 2022 at 97% for an effective yield of 9.5%. In connection with the bond agreement the Company incurred approximately $11.8 million in debt issuance costs. The Company recorded these as a discount on the debt and they are being amortized as interest expense over the contractual period of the bond agreement. As of March 31, 2024 and December 31, 2023, there was $87.3 million and $166.1 million outstanding on the Bond, respectively. As of March 31, 2024, Solis was in breach of the three financial covenants under Solis’ Bond terms: (i) the minimum Liquidity Covenant that requires the higher of €5.5 million or 5% of the outstanding Nominal Amount, (ii) the minimum Equity Ratio covenant of 25%, and (iii) the Leverage Ratio of NIBD/EBITDA to not be higher than 6.5 times for the year ended December 2021, 6.0 times for the year ended December 31, 2022 and 5.5 times for the period ending on the maturity date of the Bond. The Solis Bond carries a 3 months EURIBOR plus 6.5% per annum interest rate, and has quarterly interest payments, with a bullet payment to be paid on the Maturity Date. The Solis Bond is senior secured through a first priority pledge on the shares of Solis and its subsidiaries, a parent guarantee from Alternus Energy Group Plc, and a first priority assignment over any intercompany loans. Additionally, Solis bondholders hold a preference share in an Alternus holding company which holds certain development projects in Spain and Italy. The preference share gives the bondholders the right on any distributions up to EUR 10 million, and such assets will be divested to ensure repayment of up to EUR. 10 million should ts not be fully repaid by the Maturity Date. Additionally, because Solis was unable to fully repay the Solis Bonds by September 30, 2023, Solis’ bondholders have the right to immediately transfer ownership of Solis and all of its subsidiaries to the bondholders and proceed to sell Solis’ assets to recoup the full amount owed to the bondholders which as of March 31, 2024 is currently €80.8 million (approximately $87.3 million). If the ownership of Solis and all of its subsidiaries were to be transferred to the Solis bondholders, the majority of the Company’s operating assets and related revenues and EBIDTA would be eliminated. On October 16 2023, bondholders approved to further extend the temporary waiver to December 16, 2023. On December 18, 2023, a representative group of the bondholders approved an extension of the temporary waivers and the maturity date of the Solis Bonds until January 31, 2024, with the right to further extend to February 29, 2024 at the Solis Bond trustee’s discretion, which was subsequently approved by a majority of the bondholders on January 3, 2024. On March 12, 2024, the Solis Bondholders approved resolutions to further extend the temporary waivers and the maturity date until April 30, 2024 with the right to further extend to May 31, 2024 at the Bond Trustee’s discretion, which it granted, and thereafter on a month-to-month basis to November 29, 2024 at the Bond Trustee’s discretion and approval from a majority of Bondholders. As such, the Solis bond debt is currently recorded as short-term debt. On December 28, 2023, Solis sold 100% of the share capital in its Italian subsidiaries for approximately €15.8 million (approximately $17.5 million). On January 18, 2024, Solis sold 100% of the share capital in its Polish subsidiaries for approximately €54.4 million (approximately $59.1 million), and on February 21, 2024 Solis sold 100% of the share capital of its Netherlands subsidiary for approximately €6.5 million (approximately $7 million). Additionally, on February 14, 2024, Solis exercised its call options to repay €59,100,000 million (approximately $68.5 million) of amounts outstanding under the bonds. Subsequently, on May 1, 2024 Solis made an interest payment of €1,000,000 (approx. $1,069,985.00) to the Bondholders, which is approximately 50% of the total interest due for the first quarter of 2024. The remaining interest amount will be paid alongside, and in addition to, the next interest payment due July 6, 2024 from Solis’ ongoing business operations. Solis will incur a late payment penalty in accordance with the Bond Terms, which will also be paid in July 2024. On December 21, 2022, the Company’s wholly owned Irish subsidiaries, AEG JD 01 LTD and AEG MH 03 LTD entered in a financing facility with Deutsche Bank AG (“Lender”). This is an uncommitted revolving debt financing of €500,000,000 to finance eligible project costs for the acquisition, construction, and operation of installation/ready to build solar PV plants across Europe (the “Warehouse Facility”). The Warehouse Facility, which matures on the third anniversary of the closing date of the Credit Agreement (the “Maturity Date”), bears interest at Euribor plus an aggregate margin at a market rate for such facilities, which steps down by 0.5% once the underlying non-Euro costs financed reduces below 33.33% of the overall costs financed. The Warehouse Facility is not currently drawn upon, but a total of approximately €1,800,000 in arrangement and commitment fees is currently owed to the Lender. Once drawn, the Warehouse Facility capitalizes interest payments until projects reach their commercial operations dates through to the Maturity Date; it also provides for mandatory prepayments in certain situations. On March 21, 2024, ALCE and the Sponsor of Clean Earth (“CLIN”) agreed to a settlement of a $1.2 million note assumed by ALCE as part of the Business Combination that was completed in December 2023. The note had a maturity date of whenever CLIN closes its Business Combination Agreement and accrued interest of 25%. ALCE issued 225,000 shares to the Sponsor in March 21, 2024 and a payment plan of the rest of the outstanding balance was agreed to with payments to commence on July 15, 2024. The closing stock price of the Company was $0.47 on the date of issuance.	15. Green Bonds, Convertible and Non-convertible Promissory Notes The following table reflects the total debt balances of the Company as December 31, 2023 and 2022 (in thousands): Year Ended December 31, 2023 2022 (in thousands) Senior Secured Green Bonds $ 166,122 $ 149,481 Senior Secured debt and promissory notes secured 32,312 13,486 Total debt 198,434 162,967 Less current maturities (198,434 ) - Long term debt, net of current maturities $ - $ 162,967 Current Maturities $ 198,434 $ - Less current debt discount (892 ) - Current Maturities net of debt discount $ 197,542 $ - Long-term maturities $ - $ 162,967 Less long-term debt discount - (4,272 ) Long-term maturities net of debt discount $ - $ 158,695 During the period ended December 31, 2022, the Company incurred approximately $200 thousand of debt issuance cost related to the green bonds discussed below. The Company incurred debt issuance costs of $4.1 million during the year ended December 31, 2023. Debt issuance costs are recorded as a debt discount and are amortized to interest expense over the life of the debt, upon the close of the related debt transaction, in the Consolidated Balance Sheet. Interest expense stemming from amortization of debt discounts for continuing operations for the twelve-months ended December 31, 2023 and 2022 was $4.9 million and $3.9 million, respectively. There was no interest expense stemming from amortization of debt discounts for discontinued operations for the twelve-months ended December 31, 2023 and 2022. All outstanding debt for the company is considered short-term based on their respective maturity dates and are to be repaid within the year 2024. Senior secured debt: In May 2022, AEG MH02 entered into a loan agreement with a group of private lenders of approximately $10.8 million with an initial stated interest rate of 8% and a maturity date of May 31, 2023. In February 2023, the loan agreement was amended stating a new interest rate of 16% retroactive to the date of the first draw in June 2022. In May 2023, the loan was extended and the interest rate was revised to 18% from June 1, 2023. In July 2023, the loan agreement was further extended to October 31, 2023. In November 2023, the loan agreement was further extended to May 31, 2024. Due to these addendums, $2.4 million of interest was recognized in the period ended December 31, 2023. The Company had principal outstanding of $11.0 million and $10.7 million as of December 31, 2023 and 2022, respectively. In June 2022, Alt US 02, a subsidiary of Alternus Energy Americas, and indirect wholly owned subsidiary of the Company, entered into an agreement as part of the transaction with Lightwave Renewables, LLC to acquire rights to develop a solar park in Tennessee. The Company entered into a construction promissory note of $5.9 million with a variable interest rate of prime plus 2.5% and an original maturity date of June 29, 2023. On January 26, 2024 the loan was extended to June 29, 2024 due to logistical issues that caused construction delays. The Company had principal outstanding of $4.3 million and $2.8 million as of December 31, 2023 and 2022, respectively. On February 28, 2023, Alt US 03, a subsidiary of Alternus Energy Americas, and indirect wholly owned subsidiary of the Company, entered into an agreement as part of the transaction to acquire rights to develop a solar park in Tennessee. Alt US 03 entered into a construction promissory note of $920 thousand with a variable interest rate of prime plus 2.5% and due May 31, 2024. This note had a principal outstanding balance of $717 thousand as of December 31, 2023. In July 2023, one of the Company’s US subsidiaries acquired a 32 MWp solar PV project in Tennessee for $2.4 million financed through a bank loan having a six-month term, 24% APY, and an extended maturity date of February 29, 2024. The project is expected to start operating in Q1 2025. 100% of offtake is already secured by 30-year power purchase agreements with two regional utilities. The Company had a principal outstanding balance of $7.0 million as of December 31, 2023. As of the date of this report this loan is currently in default, but management is in active discussions with the lender to renegotiate the terms. In July 2023, Alt Spain Holdco, one of the Company’s Spanish subsidiaries acquired the project rights to construct a 32 MWp portfolio of Solar PV projects in Valencia, Spain, with an initial payment of $1.9 million, financed through a bank loan having a six-month term and accruing ’Six Month Euribor’ plus 2% margin, currently 5.9% interest. On January 24, 2024, the maturity date was extended to July 28, 2024. The portfolio consists of six projects totaling 24.4 MWp. This note had a principal outstanding balance of $3.3 million as of December 31, 2023. In October 2023, Alternus Energy Americas, one of the Company’s US subsidiaries secured a working capital loan in the amount of $3.2 million with a 0% interest until a specified date and a maturity date of March 31, 2024. In February 2024, the loan was further extended to February 28, 2025 and the principal amount was increased to $3.6 million. In March 2024, the Company began accruing interest at a rate of 10%. Additionally, the Company issued the noteholder warrants to purchase up to 90,000 shares of restricted common stock, exercisable at $0.01 per share having a 5 year term and fair value of $86 thousand. The Company had a principal outstanding balance of $3.2 million as of December 31, 2023. As of the date of this report this loan is currently in default, but management is in active discussions with the lender to renegotiate the terms. In December 2023, Alt US 07, one of the Company’s US subsidiaries acquired the project rights to a 14 MWp solar PV project in Alabama for $1.1 million financed through a bank loan having a six-month term, 24% APY, and a maturity date of May 28, 2024. The project is expected to start operating in Q2 2025. 100% of offtake is already secured by 30-year power purchase agreements with two regional utilities. This note had a principal outstanding balance of $1.1 million as of December 31, 2023. In December 2023, the Company assumed an existing loan to the Sponsors of Clean Earth with a balance of $1.6 million with a 0% interest rate until perpetuity as part of the Business Combination with Clean Earth. The Company had a principal outstanding balance of $1.6 million as of December 31, 2023. Convertible Promissory Notes: There was convertible debt outstanding for the year ended December 31, 2022. For the year ended December 31, 2023, 225,000 shares of Common Stock were issued at Closing to the Sponsor of Clean Earth to settle CLIN promissory notes of $1.6 million. The shares were issued at the closing price of $5 per share for $1.1 million. The difference of $0.5 million was recognized as an addition to Additional Paid in Capital. Management determined the extinguishment of this note is the result of a Troubled Debt Restructuring. Other Debt: In January 2021, the Company approved the issuance by one of its subsidiaries, Solis, of a series of 3-year senior secured green bonds in the maximum amount of $242.0 million (€200.0 million) with a stated coupon rate of 6.5% + EURIBOR and quarterly interest payments. The bond agreement is for repaying existing facilities of approximately $40.0 million (€33 million), and funding acquisitions of approximately $87.2 million (€72.0 million). The bonds are secured by the Solis Bond Company’s underlying assets. The Company raised approximately $125.0 million (€110.0 million) in the initial funding. In November 2021, Solis Bond Company DAC, completed an additional issue of $24.0 million (€20.0 million). The additional issue was completed at an issue price of 102% of par value, corresponding to a yield of 5.5%. The Company raised $11.1 million (€10.0 million) in March 2022 at 97% for an effective yield of 9.5%. In connection with the bond agreement the Company incurred approximately $11.8 million in debt issuance costs. The Company recorded these as a discount on the debt and they are being amortized as interest expense over the contractual period of the bond agreement. As of December 31, 2022 and 2021, there was $149.5 million and $147.2 million outstanding on the Bond, respectively. As of December 31, 2023 and 2022 there was $166.1 million and $149.4 million outstanding on the Bond, respectively. As of December 31, 2022, the Company’s wholly owned subsidiary, Solis Bond Company DAC, was in breach of the three financial covenants under Solis’ Bond terms: (i) the minimum Liquidity Covenant that requires the higher of €5.5 million or 5% of the outstanding Nominal Amount, (ii) the minimum Equity Ratio covenant of 25%, and (iii) the Leverage Ratio of NIBD/EBITDA to not be higher than 6.5 times for the year ended December 2021, 6.0 times for the year ended December 31, 2022 and 5.5 times for the period ending on the maturity date of the Bond, January 6, 2024. The Solis Bond carries a 3 months EURIBOR plus 6.5% per annum interest rate, and has quarterly interest payments, with a bullet payment to be paid on January 6, 2024. The Solis Bond is senior secured through a first priority pledge on the shares of Solis and its subsidiaries, a parent guarantee from Alternus Energy Group Plc, and a first priority assignment over any intercompany loans. In April 2023 the bond holders approved a temporary waiver and an amendment to the bond terms to allow for a change of control in Solis (which allows for the transfer of Solis and its subsidiaries underneath Clean Earth Acquisitions Corp. on Closing). In addition, bondholders received a preference share in an Alternus Midco, which will hold certain development projects in Spain and Italy. The shares will have preference on any distribution from Midco to Alternus up to €10.0 million, and Midco will divest assets to ensure repayment of the €10.0 million should the bonds not have been fully repaid at maturity (January 6, 2024). Finally, bondholders will receive a 1% amendment fee, which equates to €1.4 million. On June 5, 2023, the bondholders approved an extension to the waiver to September 30, 2023 and the bond trustee was granted certain additional information rights and the right to appoint half of the members of the board of directors of Solis, in addition to the members of the board appointed by Alternus. Under the waiver agreement, as extended, Solis must fully repay the Solid Bond by September 30, 2023. If Solis is unable to fully repay the Solis Bond by September 30, 2023, Solis’ bondholders have the right to immediately transfer ownership of Solis and all of its subsidiaries to the bondholders and proceed to sell Solis’ assets to recoup the full amount owed to the bondholders, which as of September 30, 2023 is currently €150,000,000 (approximately $159,000,000). If the ownership of Solis and all of its subsidiaries were to be transferred to the Solis bondholders, the majority of Alternus’ operating assets and related revenues and EBIDTA would be eliminated. On October 16 2023, bondholders approved to further extend the temporary waiver to December 16, 2023. As such, the Solis bond debt is currently recorded as short-term debt. In consideration for the extension the Company agreed to repay the bonds at 107.5 of par value. This incremental par value amount of $11.1 million is recognized as the “Solis bond waiver fee” on the Company’s Statement of Operations and Comprehensive Loss and is an increase to the Green Bonds in Current Liabilities in the Company’s Consolidated Balance Sheet. This was a non-cash transaction that resulted in an increase to the Company’s debt balance, and is treated as reconciling item to Net Loss on the Company’s Consolidated Statement of Cash Flows. On December 18, 2023, a representative group of the bondholders approved an extension of the temporary waivers and the maturity date of the Solis Bonds until January 31, 2024, with the right to further extend to February 29, 2024 at the Solis Bond trustee’s discretion, which was subsequently approved by a majority of the bondholders on January 3, 2024. As such, the Solis bond debt is currently recorded as short-term debt. On December 28, 2023, Solis sold 100% of the share capital in its Italian subsidiaries for approximately €15.8 million (approximately $17.3 million). Subsequently, on January 18, 2024, Solis sold 100% of the share capital in its Polish subsidiaries for approximately € € €59,100,000 million (approximately $68.5 million) of amounts outstanding under the bonds Management determined the amendments for the Bond represented a troubled debt restructuring under ASC 470-60. The result of the amendments noted above was an $11.1 million expense recorded as Solis Bond Waiver Fee on the Consolidated Statement of Operations and Comprehensive Income/(Loss). On December 21, 2022, Alternus Clean Energy’s wholly owned Irish subsidiaries, AEG JD 01 LTD and AEG MH 03 LTD entered in a financing facility with Deutsche Bank AG (“Lender”). This is a committed revolving debt financing of €80,000,000 to finance eligible project costs for the acquisition, construction, and operation of installation/ready to build solar PV plants across Europe, including the capacity for the financing to be upsized via a €420,000,000 uncommitted accordion facility to finance a pipeline of further projects across Europe with a total combined capacity of 600 MWp (the “Warehouse Facility”). The Warehouse Facility, which matures on the third anniversary of the closing date of the Credit Agreement (the “Maturity Date”), bears interest at Euribor plus an aggregate margin at a market rate for such facilities, which steps down by 0.5% once the underlying non-Euro costs financed reduces below 33.33% of the overall costs financed. The Warehouse Facility is not currently drawn upon, but a total of approximately €1,800,000 in arrangement and commitment fees is currently owed to the Lender. Once drawn, the Warehouse Facility capitalizes interest payments until projects reach their commercial operations dates through to the Maturity Date; it also provides for mandatory prepayments in certain situations.

Leases

Leases	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Leases [Abstract]
Leases	14. Leases The Company determines if an arrangement is a lease or contains a lease at inception or acquisition when the Company acquires a new park. The Company has operating leases for corporate offices and land with remaining lease terms of 4 to 28 years. Operating lease assets and operating lease liabilities are recognized based on the present value of the future lease payments over the lease term at the commencement date. As most of the Company’s leases do not provide an implicit rate, the Company estimates its incremental borrowing rate based on information available at the commencement date in determining the present value of future payments. Lease expense related to the net present value of payments is recognized on a straight-line basis over the lease term. The key components of the company’s operating leases were as follows (in thousands): March 31, December 31, 2024 2023 Operating Lease - Operating Cash Flows (Fixed Payments) 75 189 Operating Lease - Operating Cash Flows (Liability Reduction) 61 129 New ROU Assets - Operating Leases - 409 Weighted Average Lease Term - Operating Leases (years) 12.99 13.24 Weighted Average Discount Rate - Operating Leases 7.65 % 7.65 % The Company’s operating leases generally relate to the rent of office building space as well as land and rooftops upon which the Company’s solar parks are built. These leases include those that have been assumed in connection with the Company’s asset acquisitions and business combinations. The Company’s leases are for varying terms and expire between 2027 and 2051. In October 2023, the Company entered a new lease for land in Madrid, Spain where solar parks are planned to be built. The lease term is 35 years with an estimated annual cost of $32 thousand. Maturities of lease liabilities as of March 31, 2024 were as follows: (in thousands) Five-year lease schedule: 2024 Apr 1 – Dec 31 $ 154 2025 235 2026 241 2027 247 2028 215 Thereafter 2,021 Total lease payments 3,113 Less imputed interest (1,748 ) Total $ 1,365 The Company had no finance leases as of March 31, 2024.	16. Leases The Company determines if an arrangement is a lease or contains a lease at inception, or acquisition when the Company acquires a new park. The Company has operating leases for corporate offices and land with remaining lease terms of 4 to 28 years. Operating lease assets and operating lease liabilities are recognized based on the present value of the future lease payments over the lease term at the commencement date. As most of the Company’s leases do not provide an implicit rate, the Company estimates its incremental borrowing rate based on information available at the commencement date in determining the present value of future payments. Lease expense related to the net present value of payments is recognized on a straight-line basis over the lease term. The key components of the company’s operating leases were as follows (in thousands): December 31, December 31, 2023 2022 Operating Lease - Operating Cash Flows (Fixed Payments) 189 99 Operating Lease - Operating Cash Flows (Liability Reduction) 129 54 New ROU Assets - Operating Leases 409 8,482 Weighted Average Lease Term - Operating Leases (years) 13.24 7.05 Weighted Average Discount Rate - Operating Leases 7.65 % 7.10 % The Company’s operating leases generally relate to the rent of office building space, as well as land and rooftops upon which the Company’s solar parks are built. These leases include those that have been assumed in connection with the Company’s asset acquisitions and business combinations. The Company’s leases are for varying terms and expire between 2027 and 2051. In April 2022, the Company entered a new lease for office space in the US with a term of 7.5 years. The estimated annual cost of the lease is $147 thousand. In October 2023, the Company entered a new lease for land in Madrid, Spain where solar parks are planned to be built. The lease term is 35 years with an estimated annual cost of $32 thousand. In March 2022, the Company bought the Gardno and Gardno 2 parks in Poland, acquiring two operating leases to the land where the solar parks are located. The combined estimated annual cost of the leases is $69 thousand. The leases commenced in 2021 and run through 2046. These assets have been moved to discontinued operations as of December 31, 2023. Refer to Footnote 20 for more details. In March 2022, the Company bought the Rakowic park in Poland, acquiring an operating lease for the land where the solar parks are located. The combined estimated annual cost of the leases is $7 thousand. The leases commenced in 2022 and run through 2046. These assets have been moved to discontinued operations as of December 31, 2023. Refer to Footnote 20 for more details. Maturities of lease liabilities as of December 31, 2023 were as follows: (in thousands) Five-year lease schedule: 2024 $ 231 2025 237 2026 242 2027 248 2028 216 Thereafter 2,064 Total lease payments 3,238 Less imputed interest (1,811 ) Total $ 1,427 The Company had no finance leases as of December 31, 2023 and 2022.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Commitments and Contingencies [Abstract]
Commitments and Contingencies	15. Commitments and Contingencies Litigation The Company recognizes a liability for loss contingencies when it believes it is probable a liability has occurred and the amount can be reasonably estimated. If some amount within a range of loss appears at the time to be a better estimate than any other amount within the range, the Company accrues that amount. When no amount within the range is a better estimate than any other amount, the Company accrues the minimum amount in the range. The Company has established an accrual for those legal proceedings and regulatory matters for which a loss is both probable and the amount can be reasonably estimated. On May 4, 2023 Alternus received notice that Solartechnik, an international group specializing in solar installations, filed an arbitration claim against Alternus Energy Group PLC, Solis Bond Company DAC, and ALT POL HC 01 SP. Z.o.o. in the Court of Arbitration at the Polish Chamber of Commerce, claiming that PLN 24,980,589 (approximately $5.8 million) is due and owed to Solartechnik pursuant to a preliminary share purchase agreement by and among the parties that did not ultimately close, plus costs, expenses, legal fees and interest. The Company has accrued a liability for this loss contingency in the amount of approximately $6.8 million, which represents the contractual amount allegedly owed. It is reasonably possible that the potential loss may exceed our accrued liability due to costs, expenses, legal fees, and interest that are also alleged by Solartechnik as owed, but at the time of filing this report, we are unable to determine an estimate of that possible additional loss in excess of the amount accrued. The Company intends to vigorously defend this action. Contingencies Amendment to Agreement with Hover Energy, LLC On October 31, 2023, the Company amended its agreement with Hover Energy, LLC to extend the remaining $500,000 of Prepaid Development Fees to June 30, 2024.	17. Commitments and Contingencies Litigation The Company recognizes a liability for loss contingencies when it believes it is probable a liability has occurred and the amount can be reasonably estimated. If some amount within a range of loss appears at the time to be a better estimate than any other amount within the range, the Company accrues that amount. When no amount within the range is a better estimate than any other amount, the Company accrues the minimum amount in the range. The Company has established an accrual for those legal proceedings and regulatory matters for which a loss is both probable and the amount can be reasonably estimated. On May 4, 2023 Alternus received notice that Solartechnik, an international group specializing in solar installations, filed an arbitration claim against Alternus Energy Group PLC, Solis Bond Company DAC and ALT POL HC 01 SP. Z.o.o. in the Court of Arbitration at the Polish Chamber of Commerce, claiming that PLN 24,980,589 (approximately $5.8 million) is due and owed to Solartechnik pursuant to a preliminary share purchase agreement by and among the parties that did not ultimately close, plus costs, expenses, legal fees and interest. The Company has accrued a liability for this loss contingency in the amount of approximately $6.8 million, which represents the contractual amount allegedly owed. It is reasonably possible that the potential loss may exceed our accrued liability due to costs, expenses, legal fees and interest that are also alleged by Solartechnik as owed, but at the time of filing this report we are unable to determine an estimate of that possible additional loss in excess of the amount accrued. The arbitration is in its early stages, and the Company intends to vigorously defend this action. Amendment to Agreement with Hover Energy, LLC On October 31, 2023, the Company amended its agreement with Hover Energy, LLC to extend the remaining $500,000 of Prepaid Development Fees to June 30, 2024.

Asset Retirement Obligations

Asset Retirement Obligations	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Asset Retirement Obligations [Abstract]
Asset Retirement Obligations	16. Asset Retirement Obligations The Company’s AROs mostly relate to the retirement of solar park land or buildings. The discount rate used to estimate the present value of the expected future cash flows for the three months ended March 31, 2024 and the year ended December 31, 2023 was 7.7%. Activity ARO Liability - Balance January 1, 2023 $ 397 Additional obligations incurred - Disposals (235 ) Accretion expense 24 Foreign exchange gain/(loss) 11 ARO Liability - Balance December 31, 2023 $ 197 Additional obligations incurred - Disposals - Accretion expense 3 Foreign exchange gain/(loss) (4 ) ARO Liability -- March 31, 2024 $ 196	18. Asset Retirement Obligations The Company’s AROs mostly relate to the retirement of solar park land or buildings. The discount rate used to estimate the present value of the expected future cash flows for the year ended December 31, 2023 and 2022 was 7.5% and 7.1%, respectively. Activity ARO Liability - Balance January 1, 2022 $ 411 Additional obligations incurred - Accretion expense 20 Foreign exchange gain/(loss) (34 ) ARO Liability - Balance December 31, 2022 $ 397 Additional obligations incurred - Disposals (235 ) Accretion expense 24 Foreign exchange gain/(loss) 11 ARO Liability -- December 31, 2023 $ 197

Development Cost

Development Cost	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Development Cost [Abstract]
Development Cost	17. Development Cost The Company depends heavily on government policies that support our business and enhance the economic feasibility of developing and operating solar energy projects in regions in which we operate or plan to develop and operate renewable energy facilities. The Company can decide to abandon a project if it becomes uneconomic due to various factors, for example, a change in market conditions leading to higher costs of construction, lower energy rates, political factors or otherwise where governments from time to time may review their laws and policies that support renewable energy and consider actions that would make the laws and policies less conducive to the development and operation of renewable energy facilities, or other factors that change the expected returns on the project. Any reductions or modifications to, or the elimination of, governmental incentives or policies that support renewable energy or the imposition of additional taxes or other assessments on renewable energy could result in, among other items, the lack of a satisfactory market for the development and/or financing of new renewable energy projects, our abandoning the development of renewable energy projects, a loss of our investments in the projects, and reduced project returns, any of which could have a material adverse effect on our business, financial condition, results of operations, and prospects. Miscellaneous development cost $ 7 Total $ 7 Miscellaneous development cost relates to cost associated with projects abandoned during various phases, due to lack of technical, legal, or financial feasibility.	19. Development Cost The Company depends heavily on government policies that support our business and enhance the economic feasibility of developing and operating solar energy projects in regions in which we operate or plan to develop and operate renewable energy facilities. The Company can decide to abandon a project if it becomes uneconomic due to various factors, for example, a change in market conditions leading to higher costs of construction, lower energy rates, or other factors that change the expected returns on the project. In addition, political factors or otherwise where governments from time to time may review their laws and policies that support renewable energy and consider actions that would make the laws and policies less conducive to the development and operation of renewable energy facilities. Any reductions or modifications to, or the elimination of, governmental incentives or policies that support renewable energy or the imposition of additional taxes or other assessments on renewable energy, could result in, among other items, the lack of a satisfactory market for the development and/or financing of new renewable energy projects, our abandoning the development of renewable energy projects, a loss of our investments in the projects and reduced project returns, any of which could have a material adverse effect on our business, financial condition, results of operations and prospects. Development cost was $11.4 million for the year ended December 31, 2022, due to primarily to abandoning of development of renewable energy projects in Poland. The table below summarizes the development cost: Project 1 $ 10,162 Miscellaneous development cost 1,210 Total $ 11,372 These costs were primarily driven by Project 1 in Poland as a 45 million PLN (approximately $9.6 million) “breakup fee” applied when the Company did not close on the project. Of the $9.6 million due to the seller, $4.2 million has been paid and approximately $5.4 million is in Accrued Liabilities on the Consolidated Balance Sheet. Miscellaneous development cost relates to cost associated with projects abandoned during various phases, due to lack of technical, legal, or financial feasibility.

Discontinued Operations Sold

Discontinued Operations Sold	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Discontinued Operations Sold [Abstract]
Discontinued Operations Sold	18. Discontinued Operations Sold In July 2023, the Company engaged multiple parties to market the Polish and Netherlands assets to potential buyers. In the fourth quarter of 2023, the Company decided to proceed with the sales of the 6 PV parks in Poland and 1 park in the Netherlands. As the exit of these two markets represented a strategic shift for the Company, the assets were classified as discontinued operations in accordance with ASC 205-20. As of December 31, 2023, the Polish and Netherlands assets were classified as disposal groups held for sale. The balances and results of the Polish and Netherlands disposal groups are presented below. The sale of the Polish assets was finalized January 19, 2024 with a cash consideration of $59.4 million for all operating assets. In accordance with ASC 360, the company removed the disposal group and recognized a gain of $3.5 million upon the sale, of which $0.8 million were costs associated with the sale. The sale of the Netherlands assets was finalized February 21, 2024 with a cash consideration of $7.1 million for all operating assets. In accordance with ASC 360, the company removed the disposal group and recognized a loss of $1.3 million upon the sale, of which $0.5 million were costs associated with the sale. As of As of Poland 2024 2023 (in thousands) Assets: Cash & cash equivalents $ 630 $ 630 Other current assets 442 443 Property, plant, and equipment, net 63,107 63,107 Operating leases, non-current - assets 5,923 5,923 Total assets held for sale $ 70,102 $ 70,103 Liabilities: Accounts payable $ 2,933 $ 2,935 Operating leases, current – liabilities 281 281 Other current liabilities 25 1,549 Operating leases, non-current - liabilities 5,798 5,798 Other non-current liabilities 985 985 Total liabilities to be disposed of $ 10,022 $ 11,548 Net assets held for sale $ 60,080 $ 58,555 Three Months Ended Poland 2024 2023 (in thousands) Revenues $ 106 $ 1,105 Operating Expenses Cost of revenues (101 ) (936 ) Depreciation, amortization, and accretion (123 ) (609 ) Gain on disposal of asset 3,484 - Total operating expenses 3,260 (1,545 ) Income/(loss) from discontinued operations 3,366 (440 ) Other income/(expense): Interest expense (688 ) (1,224 ) Total other expenses $ (688 ) $ (1,224 ) Income/(Loss) before provision for income taxes $ 2,678 (1,664 ) Net income/(loss) from discontinued operations $ 2,678 $ (1,664 ) Impact of discontinued operations on EPS Net income/(loss) attributable to common stockholders, basic $ 2,678 $ (1,664 ) Net income/(loss) attributable to common stockholders, diluted 2,678 (1,664 ) Net income/(loss) per share attributable to common stockholders, basic $ 0.04 $ (0.03 ) Net income/(loss) per share attributable to common stockholders, diluted 0.04 (0.03 ) Weighted-average common stock outstanding, basic 65,077,094 57,500,000 Weighted-average common stock outstanding, diluted 65,077,094 57,500,000 As of As of Netherlands 2024 2023 (in thousands) Assets: Cash & cash equivalents $ 75 $ 155 Accounts receivable, net - 99 Other current assets 178 58 Property, plant, and equipment, net 7,669 7,845 Operating leases, non-current – assets 1,441 1,469 Other non-current assets 1,192 1,214 Total assets held for sale $ 10,555 $ 10,840 Liabilities: Accounts payable $ 945 $ 925 Operating leases, current – liabilities 55 55 Other current liabilities 95 430 Operating leases, non-current – liabilities 1,273 1,301 Total liabilities to be disposed of $ 2,368 $ 2,711 Net assets held for sale $ 8,187 $ 8,129 Three Months Ended Netherlands 2024 2023 (in thousands) Revenues $ 16 $ 202 Operating Expenses Cost of revenues (115 ) (61 ) Depreciation, amortization, and accretion (57 ) (126 ) Loss on disposal of asset (1,334 ) - Total operating expenses (1,506 ) (187 ) Income/(loss) from discontinued operations (1,490 ) 15 Other income/(expense): Interest expense (113 ) (248 ) Total other expenses $ (113 ) $ (248 ) Loss before provision for income taxes $ (1,603 ) $ (233 ) Net loss from discontinued operations $ (1,603 ) $ (233 ) Impact of discontinued operations on EPS Net loss attributable to common stockholders, basic $ (1,603 ) $ (233 ) Net loss attributable to common stockholders, diluted (1,603 ) (233 ) Net loss per share attributable to common stockholders, basic $ (0.02 ) $ (0.00 ) Net loss per share attributable to common stockholders, diluted (0.02 ) (0.00 ) Weighted-average common stock outstanding, basic 65,077,094 57,500,000 Weighted-average common stock outstanding, diluted 65,077,094 57,500,000	20. Discontinued Operations – Assets Held for Sale In July 2023, the Company engaged multiple parties to market the Polish and Netherlands assets to potential buyers. In the fourth quarter of 2023, the Company decided to proceed with the sales of the 6 PV parks in Poland and 1 park in the Netherlands. As the exit of these two markets represented a strategic shift for the Company, the assets were classified as discontinued operations in accordance with ASC 205-20. As of December 31, 2023, the Polish and Netherlands assets were classified as disposal groups held for sale. The Company sold the Polish assets on January 18, 2024 and the Netherland assets on February 21, 2024. The balances and results of the Polish and Netherlands disposal groups are presented below: As of December 31 Poland 2023 2022 (in thousands) Assets: Cash & cash equivalents $ 630 $ 431 Other current assets 443 1,105 Property, plant, and equipment, net 63,107 69,656 Operating leases, non-current - assets 5,923 5,378 Total assets held for sale $ 70,103 $ 76,570 Liabilities: Accounts payable $ 2,935 $ 1,760 Operating leases, current – liabilities 281 233 Other current liabilities 1,549 1,157 Operating leases, non-current - liabilities 5,798 4,995 Other non-current liabilities 985 824 Total liabilities to be disposed of $ 11,548 $ 8,969 Net assets held for sale $ 58,555 $ 67,601 Year Ended December 31, Poland 2023 2022 (in thousands) Revenues $ 7,593 $ 10,709 Operating Expenses Cost of revenues (3,768 ) (4,104 ) Depreciation, amortization, and accretion (2,563 ) (2,482 ) Loss on disposal of asset (130 ) - Total operating expenses (6,461 ) (6,586 ) Income from discontinued operations 1,132 4,123 Other income/(expense): Impairment loss recognized on the remeasurement to fair value less costs to sell (11,766 ) - Interest expense (5,650 ) (3,893 ) Other expense (157 ) (30 ) Total other expenses $ (17,573 ) $ (3,923 ) Income/(Loss) before provision for income taxes $ (16,441 ) 200 Income taxes - (21 ) Net income/(loss) from discontinued operations $ (16,441 ) $ 179 Impact of discontinued operations on EPS Net income/(loss) attributable to common stockholders, basic $ (16,441 ) $ 179 Net income/(loss) attributable to common stockholders, diluted (16,441 ) 179 Net income/(loss) per share attributable to common stockholders, basic $ (0.28 ) $ 0.00 Net income/(loss) per share attributable to common stockholders, diluted 0.00 0.00 Weighted-average common stock outstanding, basic 57,862,598 57,500,000 Weighted-average common stock outstanding, diluted 57,862,598 57,500,000 Immediately before the classification of the disposal groups as discontinued operations, the recoverable amount was estimated for certain items of property, plant and equipment and impairment loss was identified. Following the classification, a write-down of ($11.8) million was recognized on December 31, 2023 to reduce the carrying amount of the assets in the disposal group to their fair value less costs to sell. This was recognized in discontinued operations in the statement of profit or loss. Fair value measurement disclosures are provided in Footnote 5. As of December 31, Netherlands 2023 2022 (in thousands) Assets: Cash & cash equivalents $ 155 $ 13 Accounts receivable, net 99 487 Other current assets 58 82 Property, plant, and equipment, net 7,845 7,984 Operating leases, non-current – assets 1,469 1,438 Other non-current assets 1,214 1,176 Total assets held for sale $ 10,840 $ 11,180 Liabilities: Accounts payable $ 925 $ 23 Operating leases, current – liabilities 55 52 Other current liabilities 430 235 Operating leases, non-current – liabilities 1,301 1,312 Total liabilities to be disposed of $ 2,711 $ 1,622 Net assets held for sale $ 8,129 $ 9,558 Year Ended December 31, Netherlands 2023 2022 (in thousands) Revenues $ 2,840 $ 1,596 Operating Expenses Cost of revenues (450 ) (368 ) Depreciation, amortization, and accretion (400 ) (500 ) Loss on disposal of asset (7 ) - Total operating expenses (857 ) (868 ) Income from discontinued operations 1,983 728 Other income/(expense): Interest expense (1,131 ) (787 ) Other expense (62 ) - Total other expenses $ (1,193 ) $ (787 ) Income/(Loss) before provision for income taxes $ 790 $ (59 ) Income taxes (161 ) - Net income/(loss) from discontinued operations $ 629 $ (59 ) Impact of discontinued operations on EPS Net income/(loss) attributable to common stockholders, basic $ 629 $ (59 ) Net income/(loss) attributable to common stockholders, diluted 629 (59 ) Net income/(loss) per share attributable to common stockholders, basic $ 0.01 $ (0.00 ) Net income/(loss) per share attributable to common stockholders, diluted 0.01 (0.00 ) Weighted-average common stock outstanding, basic 57,862,598 57,500,000 Weighted-average common stock outstanding, diluted 57,862,598 57,500,000 Immediately before the classification of the disposal groups as discontinued operations, the recoverable amount was estimated for certain items of property, plant and equipment and no impairment loss was identified. As of December 31, 2023, there were no further write-downs as the carrying amounts of the disposal groups did not fall below its fair value less costs to sell.

Italy Sale Disclosure

Italy Sale Disclosure	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Italy Sale Disclosure [Abstract]
Italy Sale Disclosure	19. Italy Sale Disclosure In June 2023 the Company engaged an Italian firm to market the Company’s operating assets in Italy. During the fourth quarter of 2023 a buyer was identified, and the sale of the assets was finalized on December 28, 2023. The Company received a cash consideration of $17.5 million for all operating assets. In accordance with ASC 360, the Company removed the disposal group and recognized a loss of $5.5 million upon sale on December 28, 2023, of which $0.6 million were cost associated with the sale. The remaining balances and results of the Italian assets not disposed are presented below: As of Year Ended Italy 2024 2023 (in thousands) Assets: Cash & cash equivalents $ 87 $ 100 Other current assets 330 338 Other non-current assets 3,966 3,819 Total assets $ 4,383 $ 4,257 Liabilities: Accounts payable $ 17 $ 21 Other current liabilities 569 578 Total liabilities $ 586 $ 599 Net assets $ 3,797 $ 3,658 Three Months Ended Italy 2024 2023 (in thousands) Revenues $ - $ 655 Operating Expenses Cost of revenues - (262 ) Selling, general, and administrative (8 ) (42 ) Depreciation, amortization, and accretion - (410 ) Total operating expenses (8 ) (714 ) Loss from discontinued operations (8 ) (59 ) Other income/(expense): Other expense - (36 ) Total other expenses $ - $ (36 ) Loss before provision for income taxes $ (8 ) $ (95 ) Income taxes - - Net loss from discontinued operations $ (8 ) $ (95 ) Impact on EPS Net loss attributable to common stockholders, basic $ (8 ) $ (95 ) Net loss attributable to common stockholders, diluted (8 ) (95 ) Net loss per share attributable to common stockholders, basic $ (0.00 ) $ (0.00 ) Net loss per share attributable to common stockholders, diluted (0.00 ) (0.00 ) Weighted-average common stock outstanding, basic 65,077,094 57,500,000 Weighted-average common stock outstanding, diluted 65,077,094 57,500,000	21. Italy Sale Disclosure In June 2023 the Company engaged an Italian firm to market the Company’s operating assets in Italy. During the fourth quarter of 2023 a buyer was identified, and the sale of the assets was finalized on December 28, 2023. The Company received a cash consideration of $17.5 million for all operating assets. In accordance with ASC 360, the Company removed the disposal group and recognized a loss of $5.5 million upon sale on December 28, 2023, of which $0.6 million were cost associated with the sale. The balances and results of the Italian disposal group are presented below: As of Year Ended Italy 2023 2022 (in thousands) Assets: Cash & cash equivalents $ 100 $ 295 Accounts receivable, net - 932 Other current assets 338 1,030 Property, plant, and equipment, net - 21,735 Operating leases, non-current - assets - 4 Other non-current assets 3,819 800 Total assets held for sale $ 4,257 $ 24,796 Liabilities: Accounts payable $ 21 $ 109 Other current liabilities 578 1,080 Other non-current liabilities - 216 Total liabilities to be disposed of $ 599 $ 1,405 Net assets held for sale $ 3,658 $ 23,391 Year Ended December 31, Italy 2023 2022 (in thousands) Revenues $ 3,360 $ 3,354 Operating Expenses Cost of revenues (1,204 ) (812 ) Selling, general, and administrative (69 ) (77 ) Depreciation, amortization, and accretion (1,638 ) (1,614 ) Loss on disposal of asset (5,501 ) - Total operating expenses (8,412 ) (2,503 ) Income/(Loss) from discontinued operations (5,052 ) 851 Other income/(expense): Other expense (15 ) - Other income - 22 Total other expenses $ (15 ) $ 22 Income/(Loss) before provision for income taxes $ (5,067 ) $ 873 Income taxes - - Net income/(loss) from discontinued operations $ (5,067 ) $ 873 Impact on EPS Net income/(loss) attributable to common stockholders, basic $ (5,067 ) $ 873 Net income/(loss) attributable to common stockholders, diluted (5,067 ) 873 Net income/(loss) per share attributable to common stockholders, basic $ (0.09 ) $ 0.02 Net income/(loss) per share attributable to common stockholders, diluted (0.09 ) 0.02 Weighted-average common stock outstanding, basic 57,862,598 57,500,000 Weighted-average common stock outstanding, diluted 57,862,598 57,500,000

Shareholders' Equity

Shareholders' Equity	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Shareholders’ Equity [Abstract]
Shareholders’ Equity	20. Shareholders’ Equity Common Stock As of December 31, 2023, the Company had a total of 150,000,000 shares of common stock authorized with 71,905,363 shares issued and outstanding. As of March 31, 2024, the Company had a total of 150,000,000 shares of common stock authorized with 81,396,664 shares issued and outstanding. On January 23, 2024, the Company entered into a six-month marketing services agreement. The Company issued 81,301 shares at a market value of $1.01 in exchange for marketing services provided. On February 20, 2024, the Company entered into a two-month marketing services agreement. The Company issued 100,000 shares at a market value of $0.35 for marketing services provided. This agreement has the potential of renewal for an additional three months upon mutual written consent. Preferred Stock As of March 31, 2024 and December 31, 2023, the Company also had a total of 1,000,000 shares of preferred stock authorized. There were no preferred shares issued or outstanding as of March 31, 2024 and December 31, 2023. The board of directors of the Company has the authority to establish one or more series of preferred stock, fix the voting rights, if any, designations, powers, preferences and any other rights, if any, of each such series and any qualifications, limitations and restrictions thereof. Warrants As of December 31, 2023, warrants to purchase up to 12,345,000 shares of common stock were issued and outstanding. These warrants were related to financing activities. As inducement to extend the maturity of an existing note with warrants, the Company issued 90,000 additional penny warrants with a five year term to the noteholder with a five year term. As of March 31, 2024, warrants to purchase up to 12,435,000 shares of common stock were issued and outstanding. Warrants Weighted Weighted Outstanding - December 31, 2022 11,945,000 $ 11.50 5.98 Issued during the quarter - - - Expired during the quarter - - - Outstanding – March 31, 2023 11,945,000 11.50 5.98 Exercisable – March 31, 2023 11,945,000 $ 11.50 5.98 Warrants Weighted Weighted Outstanding - December 31, 2023 12,345,000 $ 11.22 4.93 Issued during the quarter 90,000 0.01 0.03 Expired during the quarter - - - Outstanding – March 31, 2024 12,435,000 11.14 4.73 Exercisable – March 31, 2024 12,435,000 $ 11.14 4.73	22. Shareholders’ Equity Common Stock As of December 31, 2022, the Company had a total of 100,000,000 shares of Class A common stock authorized and 10,000,000 shares of Class B common stock authorized. As of December 31, 2023, the Company had a total of 150,000,000 shares of common stock authorized with 71,905,363 shares issued and outstanding. Preferred Stock As of December 31, 2023 and 2022, the Company also had a total of 1,000,000 shares of preferred stock authorized. There were no preferred shares issued or outstanding as of December 31, 2023, and 2022. The board of directors of the Company has the authority to establish one or more series of preferred stock, fix the voting rights, if any, designations, powers, preferences and any other rights, if any, of each such series and any qualifications, limitations and restrictions thereof. Warrants As of December 31, 2022, warrants to purchase up to 11,945,000 shares of common stock were issued and outstanding. These warrants were related to financing activities. The Company issued additional warrants to purchase up to 400,000 shares of common stock in 2023. As of December 31, 2023, warrants to purchase up to 12,345,000 shares of common stock were issued and outstanding. Warrants Weighted Weighted Outstanding - January 31, 2022 11,945,000 $ 11.50 5.98 Issued during the year - - - Expired during the year - - - Outstanding - December 31, 2022 11,945,000 $ 11.50 5.98 Issued during the year 400,000 0.35 0.16 Expired during the year - - - Outstanding – December 31, 2023 12,345,000 11.22 4.93 Exercisable – December 31, 2023 12,345,000 $ 11.22 4.93 Convertible Note As of December 31, 2022 and 2023, no convertible notes were issued or outstanding.

Segment and Geographic Informat

Segment and Geographic Information	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Segment and Geographic Information [Abstract]
Segment and Geographic Information	21. Segment and Geographic Information The Company has two reportable segments that consist of PV operations by geographical region, U.S. Operations and European Operations. European operations represent our most significant business. The Chief Operating Decision-Maker (CODM) is the CEO. The European Segment derives revenues from three sources, Country Renewable Programs, Green Certificates and Long-term Offtake Agreements. The US Segment revenues are derived from Long-term Offtake Agreements. In evaluating financial performance, we focus on EBITDA, a non-GAAP measure, as a segment’s measure of profit or loss. EBITDA is defined as earnings before interest expense, income tax expense, depreciation and amortization. The Company uses EBITDA because management believes that it can be a useful financial metric in understanding the Company’s earnings from operations. EBITDA is not a measures of the Company's financial performance under GAAP and should not be considered as an alternative to net income or any other performance measure derived in accordance with GAAP. As a trans-Atlantic independent solar power provider, we evaluate many of our capital expenditure decisions at a regional level. Accordingly, expenditures on property, plant and equipment and associated debt by segment are presented. The following tables present information related to the Company’s reportable segments. Three Months Ended Revenue by Segment 2024 2023 (in thousands) Europe $ 2,086 $ 3,828 Europe – Discontinued Operations 123 18 United States 93 1,307 Total for the period $ 2,302 $ 5,153 Three Months Ended Operating Loss by Segment 2024 2023 (in thousands) Europe $ (2,908 ) $ (4,310 ) United States (4,675 ) (942 ) Total for the period $ (7,583 ) $ (5,252 ) As of As of Assets by Segment 2024 2023 (in thousands) Europe Fixed Assets $ 42,209 $ 125,600 Other Assets 20,735 36,728 Total for Europe $ 62,944 $ 162,328 United States Fixed Assets $ 6,556 $ 5,119 Other Assets 14,854 17,839 Total for US $ 21,410 $ 22,958 As of As of Liabilities by Segment 2024 2023 (in thousands) Europe Debt $ 99,686 $ 180,294 Other Liabilities 28,108 39,378 Total for Europe $ 127,794 $ 219,672 United States Debt $ 16,582 $ 17,247 Other Liabilities 11,697 11,621 Total for US $ 28,279 $ 28,868 Three Months Ended Revenue by Product Type 2024 2023 (in thousands) Country Renewable Programs (FIT) Europe $ 29 $ 1,248 US 93 18 Total for the period $ 122 $ 1,266 Green Certificates (FIT) Europe $ 1,575 $ 1,880 US - - Total for the period $ 1,575 $ 1,880 Energy Offtake Agreements (PPA) Europe $ 605 $ 2,007 United States - - Total for the period $ 605 $ 2,007 Three Months Ended EBITDA by Segment 2024 2023 (in thousands) Europe $ 2,258 $ 2,122 US (2,827 ) (857 ) Total for the period $ (569 ) $ 1,265 Below is a reconciliation of net income to EBITDA and adjusted EBITDA for the periods presented: Three Months Ended EBITDA Reconciliation to Net Loss 2024 2023 (in thousands) Europe EBITDA $ 2,258 $ 2,122 Depreciation, amortization, and accretion (699 ) (1,574 ) Interest expense (4,466 ) (4,858 ) Income taxes - - Net Loss $ (2,907 ) $ (4,310 ) US EBITDA $ (2,827 ) $ (857 ) Depreciation, amortization, and accretion (49 ) (2 ) Interest expense (1,317 ) (83 ) Income taxes - - Valuation on FPA Asset (483 ) - Net Loss $ (4,676 ) $ (942 ) Consolidated Net Loss $ (7,583 ) $ (5,252 )	23. Segment and Geographic Information The Company has two reportable segments that consist of PV operations by geographical region, U.S. Operations and European Operations. European operations represent our most significant business. The Chief Operating Decision-Maker (CODM) is the CEO and CFO of the Company (as a group). The European Segment derives revenues from three sources, Country Renewable Programs, Green Certificates and Long-term Offtake Agreements. The US Segment revenues are derived from Long-term Offtake Agreements. In evaluating financial performance, we focus on EBITDA, as a segment’s measure of profit or loss. EBITDA is earnings before interest expense, income tax expense, depreciation and amortization. As a trans-Atlantic independent solar power provider, we evaluate many of our capital expenditure decisions at a regional level. Accordingly, expenditures on property, plant and equipment and associated debt by segment are presented. The following tables present information related to the Company’s reportable segments. The Company did not report segments in 2022 but are retrospectively reporting segments for 2022. Year Ended December 31, Revenue by Segment 2023 2022 (in thousands) Europe $ 30,401 $ 29,368 Europe – Discontinued Operations (10,433 ) (12,305 ) United States 116 26 Total for the period $ 20,084 $ 17,089 Year Ended December 31, Operating Loss by Segment 2023 2022 (in thousands) Europe $ (46,301 ) $ (14,978 ) United States (23,163 ) (3,470 ) Total for the period $ (69,464 ) $ (18,448 ) Year Ended December 31, Assets by Segment 2023 2022 (in thousands) Europe Fixed Assets $ 125,600 $ 141,862 Other Assets 36,728 31,218 Total for Europe $ 162,328 $ 173,080 United States Fixed Assets $ 5,119 $ 599 Other Assets 17,839 4,636 Total for US $ 22,958 $ 5,235 Year Ended December 31, Liabilities by Segment 2023 2022 (in thousands) Europe Debt $ 180,294 $ 155,896 Other Liabilities 39,378 19,221 Total for Europe $ 219,672 $ 175,117 United States Debt $ 17,247 $ 2,793 Other Liabilities 11,621 2,987 Total for US $ 28,868 $ 5,780 Year Ended December 31, Revenue by Product Type 2023 2022 (in thousands) Country Renewable Programs (FIT) Europe $ 8,356 $ 9,854 US - - Total for the period $ 8,356 $ 9,854 Green Certificates (FIT) Europe $ 10,677 $ 9,452 US - - Total for the period $ 10,677 $ 9,452 Energy Offtake Agreements (PPA) Europe $ 11,368 $ 10,062 United States 116 26 Total for the period $ 11,484 $ 10,088 Year Ended December 31, Geographic Information by Segment 2023 2022 (in thousands) Europe Revenue $ 30,401 $ 29,368 Revenue – Discontinued Operations $ (10,433 ) $ (12,305 ) Long-lived assets $ 162,328 $ 173,080 United States Revenue $ 116 $ 26 Long-lived assets $ 22,958 $ 5,235 Consolidated Revenue $ 30,517 $ 29,394 Revenue – Discontinued Operations $ (10,433 ) $ (12,305 ) Long-lived assets $ 185,286 $ 178,315 Year Ended December 31, EBITDA by Segment 2023 2022 (in thousands) Europe $ 6,874 $ 6,537 US (4,560 ) (3,370 ) Total for the period $ 2,314 $ 3,167 Year Ended December 31, EBITDA Reconciliation to Net Loss 2023 2022 (in thousands) Europe EBITDA $ 6,874 $ 6,537 Depreciation, amortization, and accretion (6,563 ) (6,617 ) Interest expense (23,453 ) (14,876 ) Income taxes (161 ) (21 ) Solis Bond Waiver (11,766 ) - Impairment loss recognized on the remeasurement to fair value less costs to sell (11,232 ) - Net Loss $ (46,301 ) $ (14,977 ) US EBITDA $ (4,560 ) $ (3,370 ) Depreciation, amortization, and accretion (57 ) (42 ) Interest expense (1,889 ) (59 ) Income taxes (15 ) - Valuation on FPA Asset (16,642 ) - Net Loss $ (23,163 ) $ (3,471 ) Consolidated Net Loss $ (69,464 ) $ (18,448 ) One customer represented 35% of continuing operational revenues during the year ended December 31, 2023 compared to two customers that represented 29% for the year ended December 31, 2022. The revenues from these customers accounted for $11.4 million and $9.7 million of revenue for the year ended December 31, 2023 and 2022 respectively. Two customers represented 34% of the discontinued operational revenues during the year ended December 31, 2023 compared to two customers that represented 42% for the year ended December 31, 2022. The revenues from these customers accounted for $11.2 million and $14.2 million of revenue for the year ended December 31, 2023 and 2022 respectively. Three customers represented 61% of the Company’s continuing operational accounts receivable for the year ended December 31, 2023. One customer represented 23% of the Company’s discontinued operational accounts receivable for the year ended December 31, 2023. The company did not have any customers who represented more than 10% of accounts receivable for the year ended December 31, 2022.

Income Tax Provision

Income Tax Provision	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Income Tax Provision [Abstract]
Income Tax Provision	22. Income Tax Provision The Company’s provision from income taxes for interim periods is determined using its effective tax rate expected to be applied for the full year. The Company’s effective tax rate was 0.0% for the three months ended March 31, 2024, and 0.0%, respectively for the same period in the prior year, as it maintains a full valuation allowance against its net deferred tax assets. The Company assesses the realizability of the deferred tax assets at each reporting date. The Company continues to maintain a full valuation allowance for its net deferred tax assets. If certain substantial changes in the entity’s ownership occur, there may be an annual limitation on the amount of the carryforwards that can be utilized. The Company will continue to assess the need for a valuation allowance on its deferred tax assets.	24. Income Tax Provision Explanation of the relationship between tax expense and accounting profit: Year Ended December 31, 2023 2022 (in thousands) Income before taxes $ (53,637 ) $ (18,569 ) Tax at the applicable rate of 21% (11,263 ) (3,899 ) State income taxes, net of federal benefit - - Permanent items 5,852 1,439 Tax effect of differences in foreign tax rates 2,622 2,046 Other 302 (140 ) Change in valuation allowance 2,502 554 Actual income tax expense (benefit) $ 15 $ - The tax effects of temporary difference and carryforwards that give rise to significant portions of the net deferred tax assets were as follows: Year Ended December 31, 2023 2022 (in thousands) Deferred tax assets: Net operating losses $ 1,329 $ 1,249 Interest expense carryforward 4,343 1,948 Lease liabilities 312 207 Total deferred tax assets 5,984 3,404 Deferred tax asset valuation allowance (5,693 ) (3,203 ) Net deferred tax assets 291 201 Deferred tax liabilities: Other - (1 ) Right-of-use asset (291 ) (200 ) Total deferred tax liabilities (291 ) (201 ) Net deferred taxes $ - $ - The Company’s valuation allowance increased during 2023 by $2.5 million, primarily due to the generation of net operating losses. Future realization of the tax benefits of existing temporary differences and net operating loss carryforwards ultimately depends on the existence of sufficient taxable income within the carryforward period. Deferred tax assets have not been recognized in respect of these losses as they may not be used to offset taxable profits elsewhere in the Company and there are no other tax planning opportunities or other evidence of recoverability in the near future. Pursuant to US Internal Revenue Code Section 382, the Company’s US net operating losses may be limited to a statutorily determined annual amount if the Company experienced an ownership change. The Company is in the process of analyzing whether any changes to its capital structure resulted in an ownership change, and whether US net operating losses would be restricted in use as a result thereof. The Company also had foreign net operating loss carryovers of $3.9 million, which includes net operating loss carryovers of $2.4 million and $51 thousand in Ireland and Luxembourg, respectively. The net operating loss carryover in Luxembourg $42 thousand expires in 2040. The remaining foreign net operating loss carryovers have unlimited carryforward periods. The Company is in the process of analyzing whether any changes to its capital structure resulted in an ownership change, and whether US net operating losses would be restricted in use as a result thereof. Future realization of the tax benefits of existing temporary differences and net operating loss carryforwards ultimately depends on the existence of sufficient taxable income within the carryforward period. As of December 31, 2023, the Company performed an evaluation to determine whether a valuation allowance was needed. The Company considered all available evidence, both positive and negative, which included the results of operations for the current and preceding years. The Company determined that it was not possible to reasonably quantify future taxable income and determined that it is more likely than not that all of it deferred tax assets will not be realized. Accordingly, the Company maintained a full valuation allowance as of December 31, 2023.

Related Party

Related Party	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Related Party [Abstract]
Related Party	23. Related Party Financial assets and financial liabilities are recognized when the Company becomes a party to the contractual provisions of the instrument. AEG: Alternus Energy Group Plc (“AEG”) was an eighty percent (80%) shareholder of the Company as of December 22, 2023 and as of December 31, 2023. On October 12, 2022 AEG entered into the Business Combination Agreement with the Company and Clean Earth Acquisition Sponsor LLC (the “Sponsor”) which closed on December 22, 2023 (See FN 1).In conjunction with the Business Combination Agreement, AEG also entered into an Investor Rights Agreement. The Investor Rights Agreement provides for certain governance requirements, registration rights and a lockup agreement under which AEG is restricted from selling its shares in the Company for one year, or until December 22, 2024, other than 1,437,500 shares after March 22, 2024 and an additional 1,437,500 after June 22, 2024, provided the shares are registered under a registration statement on SEC Form S-1. In January 2024, the Company assumed a $938 thousand (€850 thousand) convertible promissory note from AEG. The note had a 10% interest maturing in March 2025. On January 3, 2024, the noteholder converted all of the principal and accrued interest owed under the note, equal to $1.0 million, into 1,320,000 shares of restricted common stock. Nordic ESG In January of 2024, the Company issued 7,765,000 shares of restricted common stock valued at $1.23 per share to Nordic ESG and Impact Fund SCSp (“Nordic ESG”) as settlement of AEG’s €8m note. This resulted in Nordic ESG becoming a related party and resulted in a decrease of AEG’s ownership of the Company from 80% to 72%. Sponsor: Clean Earth Acquisitions Sponsor LLC (“Sponsor”) was the founder and controlling shareholder of the Company during the year ended December 31, 2023 and up to the Business Combination Closing Date, December 22, 2023, when Sponsor became an 11% shareholder of the Company. The Sponsor entered into the Business Combination Agreement with the Company and AEG, and also entered into the Investor Rights Agreement and the Sponsor Support Agreement, The Sponsor agreed, pursuant to the Sponsor Support Agreement, to vote all of their shares of capital stock (and any securities convertible or exercisable into capital stock) in favor of the approval of the Business Combination and against any other transactions, as well as to waive its redemption rights, agree to not transfer securities of the Company, and waive any anti-dilution or similar protections with respect to founder shares. In order to fund working capital deficiencies or finance transaction costs in connection with a business combination, the Sponsor initially loaned $350,000 to the Company, in accordance with an unsecured promissory note (the “WC Note”) issued on September 26, 2022, under which up to $850,000 may be advanced. On August 8, 2023, the Company issued an additional $650,000 promissory note to the Sponsor to fund the Second WC Note. The Second WC Note is non-interest bearing and payable on the date which the Company consummates its initial Business Combination. Both of these notes were settled on the Business Combination closing date in exchange for 225,000 shares of the Company’s common stock. On December 18, 2023, the Sponsor entered into a non-redemption agreement (the “NRA”) with the Company and the investor named therein (the “Investor”). Pursuant to the terms of the NRA, among other things, the Investor agreed to withdraw redemptions in connection with the Business Combination on any Common Stock, held by the Investor and to purchase additional Common Stock from redeeming stockholders of the Company such that the Investor will be the holder of no fewer than 277,778 shares of Common Stock. On March 19, 2024 we entered into a settlement agreement with the Sponsor and SPAC Sponsor Capital Access (“SCA”) pursuant to which, among other things, we agreed to repay Sponsor’s debt to SCA, related to the CLIN SPAC entity extensions, in the amount of $1.4 million and issue 225,000 shares of restricted common stock valued at $0.47 per share to SCA. D&O: In connection with the Business Combination Closing, the Company entered into indemnification agreements (each, an “Indemnification Agreement”) with its directors and executive officers. Each Indemnification Agreement provides for indemnification and advancements by the Company of certain expenses and costs if the basis of the indemnitee’s involvement in a matter was by reason of the fact that the indemnitee is or was a director, officer, employee, or agent of the Company or any of its subsidiaries or was serving at the Company’s request in an official capacity for another entity, in each case to the fullest extent permitted by the laws of the State of Delaware. Consulting Agreements: On May 15, 2021 VestCo Corp., a company owned and controlled by our Chairman and CEO, Vincent Browne, entered into a Professional Consulting Agreement with one of our US subsidiaries under which it pays VestCo a monthly fee of $16,000. This agreement has a five year initial term and automatically extends for additional one year terms unless otherwise unilaterally terminated. In July of 2023, John Thomas, one of our directors, entered into a Consulting Services Agreement with one of our US subsidiaries under which it pays Mr. Thomas a monthly fee of $11,000. This agreement has a five year initial term and automatically extends for additional one year terms unless otherwise unilaterally terminated. Three Months Ended Transactions with Directors 2024 2023 (in thousands) Loan from Vestco, a related party to Board member and CEO Vincent Browne $ - $ 210 Total $ - $ 210 Three Months Ended Director’s remuneration 2024 2023 (in thousands) Remuneration in respect of services as directors $ 362 $ 74 Remuneration in respect to long term incentive schemes - - Total $ 362 $ 74	25. Related Party Financial assets and financial liabilities are recognized when the Company becomes a party to the contractual provisions of the instrument. AEG: Alternus Energy Group Plc (“AEG”) was an eighty percent (80%) shareholder of the Company as of December 22, 2023 and as of December 31, 2023. On October 12, 2022 AEG entered into the Business Combination Agreement with the Company and Clean Earth Acquisition Sponsor LLC (the “Sponsor”) which closed on December 22, 2023 (See FN 1).In conjunction with the Business Combination Agreement, AEG also entered into an Investor Rights Agreement. The Investor Rights Agreement provides for certain governance requirements, registration rights and a lockup agreement under which AEG is restricted from selling its shares in the Company for one year, or until December 22, 2024, other than 1,437,500 shares after March 22, 2024 and an additional 1,437,500 after June 22, 2024, provided the shares are registered under a registration statement on SEC Form S-1. Sponsor: Clean Earth Acquisitions Sponsor LLC (“Sponsor”) was the founder and controlling shareholder of the Company during the year ended December 31, 2023 and up to the Business Combination Closing Date, December 22, 2023, when Sponsor became an 11% shareholder of the Company. The Sponsor entered into the Business Combination Agreement with the Company and AEG, and also entered into the Investor Rights Agreement and the Sponsor Support Agreement, The Sponsor agreed, pursuant to the Sponsor Support Agreement, to vote all of their shares of capital stock (and any securities convertible or exercisable into capital stock) in favor of the approval of the Business Combination and against any other transactions, as well as to waive its redemption rights, agree to not transfer securities of the Company, and waive any anti-dilution or similar protections with respect to founder shares. In order to fund working capital deficiencies or finance transaction costs in connection with a business combination, the Sponsor initially loaned $350,000 to the Company, in accordance with an unsecured promissory note (the “WC Note”) issued on September 26, 2022, under which up to $850,000 may be advanced. On August 8, 2023, the Company issued an additional $650,000 promissory note to the Sponsor to fund the Second WC Note. The Second WC Note is non-interest bearing and payable on the date which the Company consummates its initial Business Combination. Both of these notes were settled on the Business Combination closing date in exchange for 225,000 shares of the Company’s common stock. On December 18, 2023, the Sponsor entered into a non-redemption agreement (the “NRA”) with the Company and the investor named therein (the “Investor”). Pursuant to the terms of the NRA, among other things, the Investor agreed to withdraw redemptions in connection with the Business Combination on any Common Stock, held by the Investor and to purchase additional Common Stock from redeeming stockholders of the Company such that the Investor will be the holder of no fewer than 277,778 shares of Common Stock. D&O: In connection with the Business Combination Closing, the Company entered into indemnification agreements (each, an “Indemnification Agreement”) with its directors and executive officers. Each Indemnification Agreement provides for indemnification and advancements by the Company of certain expenses and costs if the basis of the indemnitee’s involvement in a matter was by reason of the fact that the indemnitee is or was a director, officer, employee, or agent of the Company or any of its subsidiaries or was serving at the Company’s request in an official capacity for another entity, in each case to the fullest extent permitted by the laws of the State of Delaware. Consulting Agreements: On May 15, 2021 VestCo Corp., a company owned and controlled by our Chairman and CEO, Vincent Browne, entered into a Professional Consulting Agreement with one of our US subsidiaries under which it pays VestCo a monthly fee of $16,000. This agreement has a five year initial term and automatically extends for additional one year terms unless otherwise unilaterally terminated. In July of 2023, John Thomas, one of our directors, entered into a Consulting Services Agreement with one of our US subsidiaries under which it pays Mr. Thomas a monthly fee of $11,000. This agreement has a five year initial term and automatically extends for additional one year terms unless otherwise unilaterally terminated. Year Ended December 31, Transactions with Directors 2023 2022 (in thousands) Loan from Vestco, a related party to Board member and CEO Vincent Browne $ 210 $ - Final payment made to Vestco on November 16, 2023 (210 ) - Total $ - $ - Year Ended December 31, Director’s remuneration 2023 2022 (in thousands) Remuneration in respect of services as directors $ 606 $ 315 Remuneration in respect to long term incentive schemes - - Total $ 606 $ 315

Subsequent Events

Subsequent Events	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Subsequent Events [Abstract]
Subsequent Events	24. Subsequent Events Management has evaluated subsequent events that have occurred through May 21, 2024, which is the date the financial statements were available to be issued and has determined that there were no subsequent events that required recognition or disclosure in the financial statements as of and for the period ended March 31, 2024, except as disclosed below. On April 19, 2024, the Company entered into a Securities Purchase Agreement (the “Purchase Agreement”), by and between the Company and an institutional investor (the “Investor”), pursuant to which the Company agreed to issue to the Investor a senior convertible note in the principal amount of $2,160,000, issued with an eight percent (8.0%) original issue discount (the “Convertible Note”), and a warrant (the “Warrant”) to purchase up to 2,411,088 shares of the Company’s common stock at an exercise price of $0.480 per share (the “Exercise Price”). The Company received gross proceeds of $2,000,000, before fees and other expenses associated with the transaction. The Convertible Note matures on April 20, 2025 and bears interest at a rate of seven percent (7%) per annum. The Convertible Note is convertible in whole or in part at the option of the Investor into shares of Common Stock (the “Conversion Shares”) at the Conversion Price (as defined in the Convertible Note) at any time following the date of issuance of the Convertible Note. The Convertible Note is payable monthly on each Installment Date (as defined in the Convertible Note) commencing on the earlier of July 18, 2024 and the effective date of the initial registration statement in an amount equal the sum of (A) the lesser of (x) $216,000 and (y) the outstanding principal amount of the Convertible Note, (B) interest due and payable under the Convertible Note and (C) other amounts specified in the Convertible Note (such sum being the “Installment Amount”); provided, however, if on any Installment Date, no failure to meet the Equity Conditions (as defined in the Convertible Note) exists pursuant to the Convertible Note, the Company may pay all or a portion of the Installment Amount with shares of its common stock based on the Installment Conversion Price, which is the lower of (i) the Conversion Price (as defined in the Convertible Note) and (ii) the greater of (x) 92% of the average of the two (2) lowest daily VWAPs (as defined in the Convertible Note) in the ten (10) trading days immediately prior to each conversion date and (y) $0.07. Additionally on April 19, 2024, Maxim Group LLC served as the sole placement agent (the “Placement Agent”) and the Company agreed to issue the Placement Agent a warrant to purchase up to an aggregate of 241,109 shares of Common Stock (the “Placement Agent Warrant”) at an exercise price of $0.527 per share, which Placement Agent Warrant is exercisable at any time on or after the six-month anniversary of the closing date of the Private Placement and will expire on the third (3rd) anniversary of the effective date if the registration statement registering the underlying warrant shares. In addition to the Placement Agent Warrant, the Company agreed to (i) pay the Placement Agent a cash fee of 7.0% of the gross proceeds received by the Company from the Investor, and (ii) reimburse up to $50,000 of Maxim’s reasonable accountable expenses. On April 24, 2024, AEG PLC, a 71.8% shareholder of the Company and related party, transferred 100,000 shares of ALCE common stock to an institutional third party, resulting in a decrease in AEG’s ownership of the Company by 0.1%. On April 25, 2024 Joseph E. Duey, the Company’s Chief Financial Officer, resigned, effective as of April 30, 2024. Mr. Duey will be available to the Company on an as needed basis until May 31, 2024 to provide transitional services and otherwise assist as needed. Mr. Duey has advised the Company that his decision to step down from the role of Chief Financial Officer was not based on any disagreement with the Company on any matter relating to its operations, policies or practices. Mr. Duey is pursuing outsid interests not in the renewable energy industry. Vincent Browne, the Company’s Chief Executive Officer, will act as interim Chief Financial Officer. The Company will be seeking a suitable replacement in due course. On April 30, 2024 AEG and Solis Bond Company, an indirect wholly owned subsidiary and related party, announced that the Bond Trustee granted a technical extension of the Maturity Date until 31 May 2024. As was previously disclosed on 26 February 2024, the Bond Trustee, with approval from a majority of the Bondholders, may further extend the Bonds on a month to month basis to 29 November 2024. On May 1, 2024 Solis made an interest payment of EUR 1,000,000 (€1 million) to the Bondholders, which is approximately 50% of the total interest due for the first quarter of 2024. The remaining interest amount will be paid alongside, and in addition to, the next interest payment due 6 July 2024 from Solis’ ongoing business operations. Solis will incur a late payment penalty in accordance with the Bond Terms, which will also be paid on 6 July 2024. On April 30, 2024, ALT US 01 LLC (“ALT”), an indirect wholly owned subsidiary and related party, entered into a Membership Interest Purchase and Sale Agreement (the “MIPA”) by and among ALT and C2 Taiyo Fund I, LP (“C2”). Pursuant to the MIPA C2 will sell to ALT 100% of the membership interests in Taiyo Holding LLC (“Target”). The Target owns a portfolio of special purchase vehicles (SPVs) which own and operate a portfolio of solar parks across the United States, with a maximum total production capacity of approximately 80.7 MWp. In exchange, ALT will pay to C2 a Purchase Price (as defined in the MIPA) of approximately $60.2 million, minus debt, for a net purchase price of approximately $15 million, plus net working capital, and which may be further subject to adjustments pursuant to the terms and conditions of the MIPA, and subject to meeting all of the conditions precedent and other applicable terms and conditions of the MIPA. While the MIPA contemplates that closing of the acquisition will take place by no later than June 30, 2024 or such later date as the Parties to the MIPA may agree in writing, the conditions precedent to closing are such that there can be no assurance that the acquisition will be completed in that time or at all. The Company expects to use a mix of debt and equity funding for the purchase of the assets. On May 6, 2024, the Company received a letter from the listing qualifications department staff of The Nasdaq Stock Market (“Nasdaq”) notifying the Company that for the last 30 consecutive business days, the Company’s minimum Market Value of Listed Securities (“MVLS”) was below the minimum of $35 million required for continued listing on the Nasdaq Capital Market pursuant to Nasdaq listing rule 5550(b)(2). The notice has no immediate effect on the listing of the Company’s common stock, and the Company’s common stock continues to trade on the Nasdaq Capital Market under the symbol “ALCE.” In accordance with Nasdaq listing rule 5810(c)(3)(C), the Company has 180 calendar days, or until November 4, 2024, to regain compliance. The notice states that to regain compliance, the Company’s MVLS must close at $35 million or more for a minimum of ten consecutive business days (or such longer period of time as the Nasdaq staff may require in some circumstances, but generally not more than 20 consecutive business days) during the compliance period ending November 4, 2024. If the Company does not regain compliance by November 4, 2024, Nasdaq staff will provide written notice to the Company that its securities are subject to delisting. At that time, the Company may appeal any such delisting determination to a Hearings Panel. The Company intends to actively monitor the Company’s MVLS between now and November 4, 2024 and may, if appropriate, evaluate available options to resolve the deficiency and regain compliance with the MVLS rule. While the Company is exercising diligent efforts to maintain the listing of its common stock on Nasdaq, there can be no assurance that the Company will be able to regain or maintain compliance with Nasdaq listing standards. On May 8, 2024, we issued 330,000 shares of restricted common stock valued at $0.35 per share to a third party consultant in exchange for services. On May 8, 2024 we issued 100,000 shares of restricted common stock valued at $0.35 per share to a third party consultant in exchange for services. On May 15, 2024, Mohammed Javade Chaudhri, a Class I director of Alternus Clean Energy, Inc. (the “Company”), notified the Company that they will resign from the Company’s Board of Directors (the “Board”) effective immediately. Mr. Chaudhri’s decision to resign from the Board is solely for personal reasons and is not the result of any disagreement with the Company’s operations, policies or procedures, or any disagreements in respect of accounting principles, financial statement disclosure, or any issue impacting on the committees of the Board on which they served.	26. Subsequent Events Management has evaluated subsequent events that have occurred through April 10, 2024, which is the date the financial statements were available to be issued and has determined that there were no subsequent events that required recognition or disclosure in the financial statements as of and for the year ended December 31, 2023, except as disclosed below. On January 3, 2024, Solis’, an indirect wholly owned subsidiary of the Company and related party, bondholders formally approved an extension of the temporary waivers and the maturity date of the Solis Bonds until January 31, 2024, with the right to further extend to February 29, 2024 at the Solis Bond trustee’s discretion. On January 30, 2024, the Bond Trustee exercised its right to extend the waivers and the maturity date of the Bond Terms to February 29, 2024. On January 31, 2024, Solis provided notice to the trustee of the Solis Bonds of its intent to exercise call options to repay €59.1 million (approximately $69.5 million) of amounts outstanding under the bonds. On February 14, 2024, Solis exercised its call options. On February 26, 2024, the Solis Bond Trustee granted a technical extension to the Solis Bond in order for Solis to exercise its call option, and Solis provided notice to the trustee of its intent to exercise call options to repay €5.7 million (approximately $6.2 million) of amounts outstanding under the bonds. The repayment was completed on March 12, 2024. Also on February 26, 2024, Solis and a representative group of the bondholders agreed to an additional extension of the temporary waivers and the maturity date of the Solis Bond until April 30, 2024, with the right to further extend to May 31, 2024 at the Bond Trustee’s discretion, and thereafter on a month to month basis to November 29, 2024 at the Bond Trustee’s discretion and approval from a majority of bondholders. This was formally approved by the bondholders on March 12, 2024. On January 3, 2024, ALT US 08 LLC was incorporated in Delaware as a wholly owned subsidiary of Alternus Energy Americas Inc. Also on January 3, 2024, a convertible note holder converted all of the principal and accrued interest owed under the note, equal to $1.0 million, into 1,320,000 shares of restricted common stock. On January 11, 2024, we issued 7,765,000 shares of restricted common stock valued at $1.23 per share to Nordic ESG and Impact Fund SCSp (“Nordic ESG”) has settlement of AEG’s €8m note. This resulted in Nordic ESG becoming a related party and resulted in a decrease of AEG’s ownership of the Company from 80% to 72%. On January 16, 2024 Solis entered into a sale and purchase agreement to sell one operating park in the Netherlands, Rilland. The sale closed on February 21, 2024 and Solis received EUR 6.5 million (approximately $7 million). The proceeds were used to pay down the Solis Bond. Also on January 16, 2024, AEG MH 04 Limited was incorporated in Ireland as a wholly owned subsidiary of Alternus Lux 01 S.a.r.l. On January 17, 2024, a subsidiary of the Company known as AEG JD 03 Limited changed its name to Alternus Europe Limited. On January 19, 2024, all operating parks in Poland were sold by Solis in exchange for EUR 54.4 million (approximately $59.1 million). The proceeds were used to pay down the Solis Bond. On January 23, 2024 we issued 81,301 shares of restricted common stock valued at $1.01 per share to a third party consultant in exchange for services. On February 5, 2024 we amended and restated a promissory note originally issued October 3, 2023, such that the outstanding amount owed was increased from $3.2 million to $3.55 million and the maturity date was extended to February 28, 2025; we also issued to the noteholder warrants to purchase up to 90,000 shares of restricted common stock, exercisable at $0.01 per share having a 5 year term and fair value of $86 thousand. On February 20, 2024 we issued 100,000 shares of restricted common stock valued at $0.35 per share to a third party consultant in exchange for services. On March 19, 2024 we entered into a settlement agreement with Clean Earth Acquisitions Sponsor, LLC , a related party, and SPAC Sponsor Capital Access (“SCA”) pursuant to which, among other things, we agreed to repay Sponsor’s debt to SCA, related to the CLIN SPAC entity extensions, in the amount of $1.4 million and issue 225,000 shares of restricted common stock valued at $0.47 per share to SCA. On March 20, 2024, we received a letter from The Nasdaq Stock Market notifying us that, because the closing bid price for our common stock has been below $1.00 per share for 30 consecutive business days, our common stock no longer complies with the minimum bid price requirement for continued listing on The Nasdaq Capital Market. We intend to actively monitor the bid price for our common stock between now and September 16, 2024 and will consider available options to regain compliance with the minimum bid price requirement.

Accounting Policies, by Policy

Accounting Policies, by Policy (Policies)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Summary of Significant Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The Company prepares its consolidated financial statements in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”).	Basis of Presentation The Company prepares its consolidated financial statements in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”).
Basis of Consolidation	Basis of Consolidation The consolidated financial statements include the financial statements of the Company and its subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation. The results of subsidiaries acquired or disposed of during the respective periods are included in the consolidated financial statements from the effective date of acquisition or up to the effective date of disposal, as appropriate. The consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and the related notes for the year ended December 31, 2023, contained in the Company’s Annual Report on Form 10- k	Basis of Consolidation The consolidated financial statements include the financial statements of the Company and its subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation. The results of subsidiaries acquired or disposed of during the respective periods are included in the consolidated financial statements from the effective date of acquisition or up to the effective date of disposal, as appropriate.
Related Party Transactions		Related Party Transactions A Related Party transaction is any transaction, arrangement or relationship, or any series of similar transactions, arrangements or relationships, in which (i) the Company or any of its subsidiaries is or will be a participant, and (ii) any Related Party has or will have a direct or indirect interest. A Related Party is any person who is or was (since the beginning of the last fiscal year even if such person does not presently serve in that role) an executive officer or director of the Company, any shareholder owning more than 5% of any class of the Company’s voting securities, or an immediate family member of any such person. Financial assets and financial liabilities are recognized when the Company becomes a party to the contractual provisions of the instrument. Refer to Footnote 25 for more details.
Use of Estimates		Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses for the periods presented. Significant items subject to such estimates include, but are not limited to, the assumptions utilized in the valuation of the assets acquired and liabilities assumed, determination of a business combination or asset acquisition, impairment of long-lived assets, measurement of level 3 fair value assets, and recovery of capitalized cost. Management evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors, including the current economic environment, and makes adjustment when facts and circumstance dictate. These estimates are based on information available as of the date of financial statements; therefore, actual results could differ from these estimates.
Segments		egments The Company has two operating segments, U.S. Operations and European Operations, and the decision-making group is the CEO and CFO of the Company (as a group). The CODM regularly review the Reporting Packs that contain financial and operational results aggregated by geography as well as consolidated income statement, balance sheet, and equity of the overall company.
Cash and Cash Equivalents		Cash and Cash Equivalents The Company considers cash and highly liquid investments with original maturities of three months or less to be cash and cash equivalents. The Company maintains cash and cash equivalents with major financial institutions, the largest concentration in JP Morgan in the U.S, Ireland, and Italy, Unicredit in Romania, and with ING in Poland and the Netherlands. The Company may at times exceed federally insured limits or statutorily insured limits in a foreign jurisdiction. The Company periodically assesses the financial condition and due to the size and stability of the institutions believes the risk of loss to be remote.
Restricted Cash		Restricted Cash Restricted cash relates to balances that are in the bank accounts for specific defined purposes and cannot be used for any other undefined purposes. Restricted cash is primarily restricted stemming from requirements under the Green Bond terms. The balance has a debt service reserve account, per the requirements from the Bond Trustee, that issues quarterly coupons to the Bond holders.
Accounts Receivable		Accounts Receivable Accounts receivable are uncollateralized customer obligations due under normal trade terms requiring payment within that period. Accounts receivables are presented net of allowance for doubtful accounts. The Company establishes an allowance for doubtful customer accounts, through a review of historical losses, customer balances, and industry economic conditions. Under the expected loss model, a loss (or allowance) is recognized upon initial recognition of the asset that reflects all future events that may lead to a loss being realized, regardless of whether it is probable that the future event will occur. The Company extends credit based on an evaluation of customers’ financial condition and determines any additional collateral requirements. Exposure to losses on receivables is principally dependent on each customer’s financial condition. The Company considers invoices past due when they are outstanding longer than the stated term. Under the expected loss model, a loss (or allowance) is recognized upon initial recognition of the asset that reflects all future events that may lead to a loss being realized, regardless of whether it is probable that the future event will occur. Management considers the carrying value of accounts receivable to be fully collectible. If amounts become uncollectible, they are charged to operations in the period in which that determination is made. The allowance for credit losses was $7 thousand an $0 as of December 31, 2023 and 2022 respectively.
Concentration of Credit Risk		Concentration of Credit Risk At times, the Company maintains cash balances in financial institutions which may exceed federally insured limits. The Company maintains cash balances in all countries in which it operates and in Ireland where the Company is headquartered. Government coverage for the Company’s cash balances are as follows: ● European Union - $105,841 (€100,000) per account is covered for operations in Romania, Poland, Italy, the Netherlands, and the Company’s headquarters in Ireland. ● United States - $250,000 The Company has four cash accounts across the European countries and a net of $18.8 million above government insurance amounts. The Company has six cash accounts across the United States and a net of $2.5 million above the government insurance amounts. The Company has not experienced any losses relating to such accounts and believes it is not exposed to significant credit risk on its cash and cash equivalents or restricted cash. Additionally, one customer represented 35% of continuing operational revenues during the year ended December 31, 2023 and three customers represented 61% of the Company’s continuing operational accounts receivable for the year ended December 31, 2023. These concentrations represent a risk to revenues and cash flows should these customers face financial difficulties.
Economic Concentrations		Economic Concentrations The Company and its subsidiaries own and operate solar generating facilities installed on buildings and land located across Europe and the US. Future operations could be affected by changes in the economy, other conditions in those geographic areas or by changes in the demand for renewable energy.
Property and Equipment		Property and Equipment Property and equipment are stated at cost less accumulated depreciation, amortization and impairment. The cost of an asset comprises its purchase price and any directly attributable costs of bringing the asset to its present working condition and location for its intended use. Depreciation is computed on a straight-line basis over the estimated useful lives. The useful lives per asset class are as follows: ● Solar Energy Facilities carry a useful life of the lesser of 35 years from the original placed in-service date or the lease term of the land on which they are built. ● Leasehold improvements are amortized over the shorter of the lease term or their estimated useful file. ● Furniture and fixtures carry a useful life of 3 years. ● Software and computer equipment carry a useful life of 3 and 5 years respectively. Expenditures for major renewals and betterments which substantially extend the useful life of assets are capitalized. Expenditures for maintenance and repairs, which do not materially extend the useful lives of assets, are charged to expense as incurred. Upon retirement, sale or other disposition of equipment, the cost and accumulated depreciation are removed from the respective accounts and a gain or loss, if any, is recognized in income/(loss) from operations in the Consolidated Statements of Operations and Comprehensive Loss during the year of disposal. When the Company abandons the anticipated construction of a new solar energy facility during the development phase, costs previously capitalized to development in progress are written off at the parent company.
Capitalized Development Cost		Capitalized Development Cost Capitalized development cost relates to various projects that are under development for the period. As management determines to proceed with the development of a new solar park, or purchase an existing construction project of a solar park, cost toward the final value of that project are recorded in Capitalized Development Cost on the Consolidated Balance Sheet. Cost can include, but are not limited to, financial, technical and legal due diligence costs. As the Company closes either the purchase or development of new solar parks and begins construction in process and then are added to the final asset displayed in Property, and Equipment. If the Company does not close on the prospective project, these costs are written off to Development Cost on the Consolidated Statement Operations and Comprehensive Loss.
Impairment of Solar Energy Facilities		Impairment of Solar Energy Facilities The Company reviews its investments in property and equipment for impairment whenever events or changes in circumstances indicate that the carrying value of an asset may not be recoverable. Impairment is evaluated at the asset group level, which is determined based upon the lowest level of separately identifiable cash flows. When evaluating for impairment, if the estimated undiscounted cash flows from the use of the asset group are less than the asset group’s carrying amount, then the asset group is deemed to be impaired and is written down to its fair value. Fair value is determined by net realizable value of the assets using ASC 820. The amount of the impairment loss is equal to the excess of the asset group’s carrying value over its estimated fair value During the year ended December 31, 2023, the Company recorded an impairment loss of $11.8 million in the Consolidated Statement of Operations and Comprehensive Loss related to the Polish assets held for sale to reduce the carrying amount of the assets in the disposal group to their fair value less costs to sell. This was recognized in discontinued operations on the Consolidated Statement of Operations and Comprehensive Loss.
Deferred Financing Costs and Debt Discount Amortization		Deferred Financing Costs and Debt Discount Amortization The Company incurs expenses related to debt arrangements. These deferred financing costs and debt discount costs are capitalized and amortized over the term of the related debt or revolving credit facilities and netted against the related debt.
Asset Retirement Obligations		Asset Retirement Obligations In connection with the acquisition or development of solar energy facilities, the Company may have the legal requirement to remove long-lived assets constructed on leased property and to restore the leased property to its condition prior to the construction of the long-lived assets. This legal requirement is referred to as an asset retirement obligation (ARO). If the Company determines that an ARO is required for a specific solar energy facility, the Company records the present value of the estimated future liability when the solar energy facility is placed in service as an ARO liability. The discount rate used to estimate the present value of the expected future cash flows for the year ended December 31, 2023 and 2022 was 7.3% and 7.1% respectively. The Company accretes the ARO liability to its future value over the solar energy facility’s useful life and records the related interest expense to amortization expense on the consolidated statement of operations. Solar facilities that require AROs are recorded as part of the carrying value of property and depreciated over the solar energy facility’s useful life.
Leases		Leases In February 2016, the FASB established Topic 842, Leases, by issuing Accounting Standards Update (ASU) No. 2016-02, which requires lessees to recognize leases on-balance sheet and disclose key information about leasing arrangements. Topic 842 was subsequently amended by ASU No. 2018-01, Land Easement Practical Expedient for Transition to Topic 842; ASU No. 2018-10, Codification Improvements to Topic 842, Leases; and ASU No. 2018-11, Targeted Improvements. The new standard establishes a right-of-use model (ROU) that requires a lessee to recognize a ROU asset and lease liability on the balance sheet for all leases with a term longer than 12 months. Leases will be classified as finance or operating, with classification affecting the pattern and classification of expense recognition in the income statement. A modified retrospective transition approach is required, applying the new standard to all leases existing at the date of initial application. The Company adopted the new standard on January 1, 2022 and used the effective date as our date of initial application. Consequently, financial information will not be updated and the disclosures required under the new standard will not be provided for dates and periods before January 1, 2022. The new standard provides a number of optional practical expedients in transition. We elected the ‘package of practical expedients’, which permits us not to reassess under the new standard our prior conclusions about lease identification, lease classification and initial direct costs. Upon adoption the company recognized $8.8 million of Right of Use Assets and $8.7 million of associated liabilities. Lease assets and liabilities are recognized based on the present value of the future lease payments over the lease term at the lease commencement date and are presented on the consolidated statements of financial condition. The Company estimates its incremental borrowing rate based on information available at the commencement date in determining the present value of future payments. For additional information, see Footnote 16 - Leases. Operating lease expense attributable to site leases is reported within cost of revenues in the Company’s Statement of Operations and Comprehensive Loss; whereas lease expense attributable to all other operating leases is reported within selling, general, and administrative expense in the Company’s Statement of Operations and Comprehensive Loss.
Revenue Recognition		Revenue Recognition The Company follows the guidance of the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 606, Revenue from Contracts with Customers (“ASC 606”). The core principle underlying revenue recognition under ASC 606 is that revenue should be recognized as goods or services are transferred to customers in an amount that reflects the consideration to which the Company expects to be entitled. ASC 606 defines a five-step process to achieve this core principle. ASC 606 also mandates additional disclosure about the nature, amount, timing and uncertainty of revenues and cash flows arising from customer contracts, including significant judgments, and changes in judgments and assets recognized from costs incurred to obtain or fulfill a contract. The Company derives revenues through its subsidiaries from the sale of electricity and the sale of solar renewable energy credits (RECs) in Romania and guarantees of origin certificates (GoOs) in Poland. The Company receives Green Certificates based on the amount of energy produced in Romania. Energy generation revenue and solar renewable energy credits revenue are recognized as electricity generated by the Company’s solar energy facilities is delivered to the grid, at which time all performance obligations have been delivered. Revenues are based on actual output and contractual sale prices set forth its customer contracts. The Company’s current portfolio of renewable energy facilities is generally contracted under long-term Country Renewable Programs (FIT programs) in Italy or Energy Offtake Agreements (PPAs/VPPAs) with creditworthy counterparties in Poland, Romania and the United States. Pricing of the electricity sold under these FITs and PPAs is generally fixed for the duration of the contract, although some of its PPAs have price escalators based on an index (such as the consumer price index) or other rates specified in the applicable PPA. One solar park in the Netherlands receives pre-payments calculated at the beginning of the year and based on the previous years’ production (MWhs produced) multiplied by a calculated average price per MWh for the year and divided by twelve. The Company books revenue monthly by multiplying actual production per the Company’s meters by the average price provided by the Offtaker at the beginning of the year to estimate revenue for the month. There is a true-up performed in June of the following year using actual power produced for the previous year multiplied by the average EPEX price (average actual market price per KWh for the year) less the prepayment for the year. If the true-up calculation is positive, The Offtaker settles with a payment to the Company. If the true-up is negative, the Company settles with a payment to Offtaker.
Disaggregated Revenues		Disaggregated Revenues The following table shows the Company’s revenues disaggregated by country and contract type: Year Ended December 31, Revenue by Country 2023 2022 (in thousands) Italy $ 3,360 $ 3,354 Romania 16,608 13,710 United States 116 25 Total for continuing operations $ 20,084 $ 17,089 Discontinued Operations: Netherlands $ 2,840 $ 1,596 Poland 7,593 10,709 Total for discontinued operations $ 10,433 $ 12,305 Total for the period $ 30,517 $ 29,394 Year Ended December 31, Revenue by Offtake Type 2023 2022 (in thousands) Country Renewable Programs $ 2,972 $ 2,885 Green Certificates 10,548 9,409 Energy Offtake Agreements 6,560 4,795 Other Revenue 4 - Total for continuing operations $ 20,084 $ 17,089 Discontinued Operations: Country Renewable Programs $ 5,499 $ 6,994 Guarantees of Origin 129 44 Energy Offtake Agreements 4,805 5,267 Total for discontinued operations $ 10,433 $ 12,305 Total for the period $ 30,517 $ 29,394 One customer represented 35% of continuing operational revenues during the year ended December 31, 2023 compared to two customers that represented 29% for the year ended December 31, 2022. The revenues from these customers accounted for $11.4 million and $9.7 million of revenue for the year ended December 31, 2023 and 2022 respectively. Two customers represented 34% of the discontinued operational revenues during the year ended December 31, 2023 compared to two customers that represented 42% for the year ended December 31, 2022. The revenues from these customers accounted for $11.2 million and $14.2 million of revenue for the year ended December 31, 2023 and 2022 respectively. Three customers represented 61% of the Company’s continuing operational accounts receivable for the year ended December 31, 2023. One customer represented 23% of the Company’s discontinued operational accounts receivable for the year ended December 31, 2023. The company did not have any customers who represented more than 10% of accounts receivable for the year ended December 31, 2022.
Unbilled Energy Incentives Earned		Unbilled Energy Incentives Earned The Company derives revenues from the sale of green certificates for the Romania projects. The green certificates revenues are recognized in the month they are generated by the solar project and registered with the local authority. The Company considers them unbilled at the end of the period if they have not been invoiced to a third-party customer.
Cost of Revenue		Cost of Revenue Cost of revenue primarily consists of operations and maintenance expense, insurance premiums, property taxes and other miscellaneous costs associated with the operations of solar energy facilities. Costs are charged to expense as incurred.
Taxes Recoverable and Payable		Taxes Recoverable and Payable The Company records taxes recoverable when there has been an overpayment of taxes due to timing of the Value Added Tax (VAT) between vendors and customers. The VAT tax can also be offset against a Country’s income taxes where the VAT was registered.
Development Cost		Development Cost Development costs are incurred when the Company abandons the development or acquisition of renewable energy projects. The Company depends heavily on government policies that support our business and enhance the economic feasibility of developing and operating solar energy projects in regions in which we operate or plan to develop and operate renewable energy facilities. The Company can decide to abandon a project if it becomes uneconomic due to various factors, for example, a change in market conditions leading to higher costs of construction, lower energy rates, or other factors that change the expected returns on the project. In addition, political factors or otherwise where governments from time to time may review their laws and policies that support renewable energy and consider actions that would make the laws and policies less conducive to the development and operation of renewable energy facilities. Any reductions or modifications to, or the elimination of, governmental incentives or policies that support renewable energy or the imposition of additional taxes or other assessments on renewable energy, could result in, among other items, the lack of a satisfactory market for the development and/or financing of new renewable energy projects, our abandoning the development of renewable energy projects, a loss of our investments in the projects and reduced project returns, any of which could have a material adverse effect on our business, financial condition, results of operations and prospects. At the time The Company decides to abandon a project, Development Cost are recognized on the Consolidated Statements of Operations and Other Comprehensive Income/(Loss)
Risks and Uncertainties		Risks and Uncertainties The Company’s operations are subject to significant risks and uncertainties including financial, operational, technological, and regulatory risks and the potential risk of business failure. See Note 2 regarding going concern matters.
Fair Value of Financial Instruments		Fair Value of Financial Instruments The Company measures its financial instruments at fair value. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. U.S. GAAP establishes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value into three (3) broad levels. The fair value hierarchy gives the highest priority to quoted prices (unadjusted) in active markets for identical assets or liabilities and the lowest priority to unobservable inputs. The three (3) levels of fair value hierarchy are described below: Level 1 – Quoted market prices available in active markets for identical assets or liabilities as of the reporting date. Level 2 – Pricing inputs other than quoted prices in active markets included in Level 1 that are either directly or indirectly observable as of the reporting date. Inputs are observable, unadjusted quoted prices in active markets for similar assets or liabilities, unadjusted quoted prices for identical or similar assets or liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities. Level 3 – Pricing inputs that are unobservable. Financial assets are considered Level 3 when their fair values are determined using pricing models, discounted cash flow methodologies or similar techniques, and at least one significant model assumption or input is unobservable. The Company holds various financial instruments that are not required to be measured at fair value. For cash and cash equivalents, restricted cash, accounts receivable, various debt instruments, prepayments and other current assets, accounts payable, accrued liabilities and other current liabilities, the carrying value approximated their fair values due to the short-term maturity of these instruments. The Company’s forward purchase agreement asset is considered a Level 3 financial instrument at fair value and is described below (see Note 5).
Business Combinations and Acquisition of Assets		Business Combinations and Acquisition of Assets The Company applies the definition of a business in ASC 805, Business Combinations, When an acquired group of assets does not constitute a business, the transaction is accounted for as an asset acquisition. The cost of assets acquired, and liabilities assumed in asset acquisitions is allocated based upon relative fair value. The fair value measurements of the solar facilities acquired, and asset retirement obligations assumed were derived utilizing an income approach and based, in part, on significant inputs not observable in the market. These inputs include, but are not limited to, estimates of future power generation, commodity prices, operating costs, and appropriate discount rates. These inputs require significant judgments and estimates at the time of the valuation. Transaction costs, including legal and financing fees directly related to the acquisition, incurred are capitalized as a component of the assets acquired. The allocation of the purchase price directly affects the following items in the Company’s consolidated financial statements: ● The amount of purchase price allocated to the various tangible and intangible assets and liabilities on the Company Balance Sheet, ● The amounts allocated to all other tangible assets and intangibles are amortized to depreciation or amortization expense, with the exception of favorable and unfavorable rate land leases and unfavorable rate Operation and Maintenance (O&M) contracts which are amortized to cost of revenue; and The period of time over which tangible and intangible assets and liabilities are depreciated or amortized varies, and thus, changes in the amounts allocated to these assets and liabilities will have a direct impact on the Company’s results of operations.
Income Taxes		Income Taxes Deferred taxes are determined using the asset and liability method; whereby, deferred tax assets are recognized for deductible temporary differences, operating loss and tax credit carry forwards, and deferred tax liabilities are recognized for taxable temporary differences. Temporary differences are the differences between the reported amounts of assets and liabilities and their tax basis. Valuation allowances are established when necessary to reduce deferred tax assets to the amount expected to be realized. Deferred tax assets and liabilities are adjusted for the effects of changes in tax laws and rates on the date of enactment. The Company evaluated the provisions of ASC 740 related to the accounting for uncertainty in income taxes recognized in the financial statements. ASC 740 prescribes a comprehensive model for how a company should recognize, present, and disclose uncertain positions that the company has taken or expects to take in its return. For those benefits to be recognized, a tax position must be more-likely-than-not to be sustained upon examination by taxing authorities. Differences between the positions taken or expected to be taken in a tax return and the benefit recognized and measured pursuant to the interpretation are referred to as “unrecognized benefits”. A liability is recognized for an unrecognized tax benefit because it represents an enterprise’s potential future obligation to the taxing-authority for a tax position that was not recognized as a result of applying the provisions of ASC 740. As a result of the Tax Cuts and Jobs Act (TCJA) of 2017, the Company analyzed if a liability needed to be recorded for the deemed repatriation of undistributed earnings. It was determined that there is no outstanding liability associated with this based on overall negative undistributed earnings (accumulated deficit) in the consolidated foreign group. An additional provision of the TCJA is the implementation of the Global Intangible-Low Taxed Income Tax, or “GILTI.” The Company has elected to account for the impact of GILTI in the period in which the tax actually applies to the Company. Penalties and interest assessed by income tax authorities would be included in income tax expense. For the period ended December 31, 2023, the Company did not incur any penalties or interest.
Stock-Based Compensation		Stock-Based Compensation The Company accounts for stock-based compensation in accordance with ASC 718. Stock-based compensation expense for equity instruments issued to employees and non-employees is measured based on the grant-date fair value of the awards. The fair value of each stock unit is determined based on the valuation of the Company’s stock on the date of grant. The fair value of each stock option is estimated on the date of grant using the Black-Scholes-Merton stock option pricing valuation model. The Company uses the simplified method for calculating the expected term of their options. The Company recognizes compensation costs using the straight-line method for equity compensation awards over the requisite service period of the awards, which is generally the awards’ vesting period. The Company accounts for forfeitures of awards in the period they occur. Use of the Black-Scholes-Merton option-pricing model requires the input of highly subjective assumptions, including (1) the expected terms of the option, (2) the expected volatility of the price of the Company’s common stock, and (3) the expected dividend yield of our common stock. The assumptions used in the option-pricing model represent management’s best estimates. These estimates involve inherent uncertainties and the application of management’s judgments. If factors change and different assumptions are used, the Company’s stock-based compensation expense could be materially different in the future. Additional inputs to the Black-Scholes-Merton option-pricing model include the risk-free interest rate and the fair value of the Company’s common stock. The Company determines the risk-free interest rate by using the U.S. Treasury Rates of the same period as the expected term of the stock-option.
Net Loss Per Share		Net Loss Per Share Net loss per share is computed pursuant to ASC 260, Earnings per Share Year Ended December 31, 2023 2022 (in thousands) Warrants 12,345 11,945 Total 12,345 11,945
Foreign Currency Transactions and Other Comprehensive Loss		Foreign Currency Transactions and Other Comprehensive Loss Foreign currency transactions are those transactions whose terms are denominated in a currency other than the currency of the primary economic environment in which the Company operates, which is referred to as the functional currency. The functional currency of the Company’s foreign subsidiaries is typically the applicable local currency which is Romanian Lei (RON), Polish Zloty (PLN) or European Union Euros (EUR). Transactions denominated in foreign currencies are remeasured to the functional currency using the exchange rate prevailing at the balance sheet date for balance sheet accounts and using an average exchange rate during the period, which approximates the daily exchange rate, for income statement accounts. Foreign currency gains or losses resulting from such remeasurement are included in the Consolidated Statement of Operations in the period in which they arise. Transaction gains and losses are recognized in the Company’s Results of Operations based on the difference between the foreign exchange rates on the transaction date and on the reporting date. The Company had an immaterial net foreign exchange loss for the year ended December 31, 2023 and 2022. The translation from functional foreign currency to United States Dollars (U.S. Dollar) is performed for balance sheet accounts using current exchange rates in effect at the balance sheet date and using an average exchange rate during the period, which approximates the daily exchange rate, for income statement accounts. The effects of translating financial statements from functional currency to reporting currency are recorded in other comprehensive income. For the years ended December 31, 2023 and 2022, the increase/(decrease) in comprehensive loss related to foreign currency translation gains was $0.7 million and ($1.0) million, respectively.
Recently Adopted Accounting Pronouncements		Recently Adopted Accounting Pronouncements In June 2016, the FASB issued Accounting Standards Update (ASU) No. 2016-13, Financial Instruments-Credit losses (Topic 326), subsequently amended by ASU 2020-2. This new guidance will change how entities account for credit impairment for trade and other receivables, as well as for certain financial assets and other instruments held at amortized cost. The update will replace the current incurred loss model with an expected loss model. Under the incurred loss model, a loss (or allowance) is recognized only when an event has occurred (such as a payment delinquency) that causes the entity to believe that a loss is probable (that is has been “incurred”). Under the expected loss model, a loss (or allowance) is recognized upon initial recognition of the asset that reflects all future events that may lead to a loss being realized, regardless of whether it is probable that the future event will occur. The incurred loss model considers past events and conditions, while the expected loss model includes expectations for the future which have yet to occur. ASU 2018-19 was issued in November 2018 and excludes operating leases from the new guidance. The standard will require entities to record a cumulative-effect adjustment to the balance sheet as of the beginning of the first reporting period in which the guidance is effective. For public business entities that meet the definition of a U.S. Securities and Exchange (SEC) filer, the update is effective for fiscal years beginning after December 15, 2022, including interim periods within those fiscal years. As an Emerging Growth Company, the standard is effective for the Company’s annual reporting period and interim periods beginning first quarter of 2023. The Company has adopted this standard as of January 1, 2023 and the adoption did not have a material impact on the consolidated financial statements. In August 2020, the FASB issued Accounting Standards Update 2020-06, Debt-Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging – Contracts in Entity’s Own Equity (Subtopic 815-40). The ASU simplifies the accounting for certain financial instruments with characteristics of liabilities and equity. The FASB reduced the number of accounting models for convertible debt and convertible preferred stock instruments and made certain disclosure amendments to improve the information provided to users. In addition, the FASB amended the derivative guidance for the “own stock” scope exception and certain aspects of EPS guidance. For public business entities that meet the definition of a SEC filer, excluding entities eligible to be a smaller reporting company as defined by the SEC, the guidance is effective for fiscal years beginning after December 15, 2021, including interim periods within those fiscal years. For all other entities, the guidance is effective for fiscal years, including interim periods within those fiscal years, beginning after December 15, 2023. Early adoption is permitted, but no earlier than fiscal years beginning after December 15, 2020, including interim periods within those fiscal years. The Company has adopted this standard as of January 1, 2023 and the adoption did not have a material impact on the condensed consolidated financial statements.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In December 2023, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures to enhance the transparency of income tax disclosures relating to the rate reconciliation, disclosure of income taxes paid, and certain other disclosures. The ASU should be applied prospectively and is effective for annual periods beginning after December 15, 2024, with early adoption permitted. The Company is currently evaluating the impact on the related disclosures; however, it does not expect this update to have an impact on its financial condition or results of operations. In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures to improve the disclosures about reportable segments and include more detailed information about a reportable segment’s expenses. This ASU also requires that a public entity with a single reportable segment, provide all of the disclosures required as part of the amendments and all existing disclosures required by Topic 280. The ASU should be applied retrospectively to all prior periods presented in the financial statements and is effective for fiscal years beginning after December 15, 2023 and interim periods within fiscal years beginning after December 15, 2024. Early adoption is permitted. The Company is currently evaluating the impact on the financial statements and related disclosures.	Recent Accounting Pronouncements In December 2023, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures to enhance the transparency of income tax disclosures relating to the rate reconciliation, disclosure of income taxes paid, and certain other disclosures. The ASU should be applied prospectively and is effective for annual periods beginning after December 15, 2024, with early adoption permitted. The Company is currently evaluating the impact on the related disclosures; however, it does not expect this update to have an impact on its financial condition or results of operations. In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures to improve the disclosures about reportable segments and include more detailed information about a reportable segment’s expenses. This ASU also requires that a public entity with a single reportable segment, provide all of the disclosures required as part of the amendments and all existing disclosures required by Topic 280. The ASU should be applied retrospectively to all prior periods presented in the financial statements and is effective for fiscal years beginning after December 15, 2023 and interim periods within fiscal years beginning after December 15, 2024. Early adoption is permitted. The Company is currently evaluating the impact on the financial statements and related disclosures.

Organization and Formation (Tab

Organization and Formation (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Organization and Formation [Abstract]
Schedule of Operating Subsidiaries	Alternus Clean Energy Inc. is a holding company that operates through the following forty-two operating subsidiaries as of March 31, 2024: Subsidiary Principal Date Acquired / ALCE Ownership Country of Power Clouds S.r.l. SPV 31 March 2015 Solis Bond Company DAC Romania F.R.A.N. Energy Investment S.r.l. SPV 31 March 2015 Solis Bond Company DAC Romania PC-Italia-01 S.r.l. Sub-Holding SPV 15 May 2015 AEG MH 02 Limited Italy PC-Italia-03 S.r.l. SPV 1 July 2020 AEG MH 02 Limited Italy PC-Italia-04 S.r.l. SPV 15 July 2020 AEG MH 02 Limited Italy Solis Bond Company DAC Holding Company 16 October 2020 AEG JD 03 Limited Ireland ALT US 03, LLC LLC 4 May 2022 ALT US 03 LLC USA Alternus Energy Americas Inc. Holding Company 10 May 2021 Alternus Energy Group Pl USA LJG Green Source Energy Beta S.r.l SPV 29 July 2021 Solis Bond Company DAC Romania Ecosfer Energy S.r.l. SPV 30 July 2021 Solis Bond Company DAC Romania Lucas EST S.r.l. SPV 30 July 2021 Solis Bond Company DAC Romania Risorse Solari I S.r.l. SPV 28 September 2019 AEG MH 02 Limited Italy Risorse Solari III S.r.l. SPV 3 August 2021 AEG MH 02 Limited Italy Alternus Iberia S.L. SPV 4 August 2021 AEG MH 02 Limited Spain AED Italia-01 S.r.l. SPV 22 October 2021 AEG MH 02 Limited Italy AED Italia-02 S.r.l. SPV 22 October 2021 AEG MH 02 Limited Italy AED Italia-03 S.r.l. SPV 22 October 2021 AEG MH 02 Limited Italy AED Italia-04 S.r.l. SPV 22 October 2021 AEG MH 02 Limited Italy AED Italia-05 S.r.l. SPV 22 October 2021 AEG MH 02 Limited Italy ALT US 01 LLC SPV 6 December 2021 Alternus Energy Americas Inc. USA AEG MH 01 Limited Holding Company 8 March 2022 Alternus Lux 01 S.a.r.l. Ireland AEG MH 02 Limited Holding Company 8 March 2022 AEG JD 03 Limited Ireland ALT US 02 LLC Holding Company 8 March 2022 Alternus Energy Americas Inc. USA AEG JD 01 Limited Holding Company 16 March 2022 AEG MH 03 Limited Ireland Alternus Europe Limited (f/k/a AEG JD 03 Limited) Holding Company 21 March 2022 Alternus Lux 01 S.a.r.l. Ireland Alt Spain 03, S.L.U. SPV 31 May 2022 Alt Spain Holdco S.L. Spain AEG MH 03 Limited Holding Company 10 June 2022 AEG MH 01 Limited Ireland Lightwave Renewables, LLC SPV 29 June 2022 ALT US 02 LLC USA Alt Spain Holdco, S.L.U. Holding Company Acquired 14 July 2022 AEG MH 02 Limited Spain AED Italia-06 S.r.l. SPV 2 August 2022 AEG MH 02 Limited Italy AED Italia-07 S.r.l. SPV 2 August 2022 AEG MH 02 Limited Italy AED Italia-08 S.r.l. SPV 5 August 2022 AEG MH 02 Limited Italy ALT US 04 LLC Holding Company 14 September 2022 Alternus Energy Americas Inc. USA Alternus LUX 01 S.a.r.l. Holding Company 5 October 2022 Alternus Energy Group Plc Luxembourg Alt Spain 04, S.L.U. SPV May 2022 Alt Spain Holdco, S.L.U. Spain Alt Alliance LLC Holding Company September 2023 Alternus Energy Amercias Inc. USA ALT US 05 LLC Holding Company September 2023 Alternus Energy Americas Inc. USA ALT US 06 LLC Holding Company October 2023 Alternus Energy Americas Inc. USA ALT US 07 LLC Holding Company November 2023 Alternus Energy Americas Inc. USA AEG MH 04 Limited Holding Company January 2024 AEG MH 04 Limited Ireland ALT US 08 LLC Holding Company January 2024 Alternus Energy Americas Inc. USA ALT US AM LLC Holding Company March 2024 Alternus Energy Americas Inc. USA	Alternus Clean Energy Inc. is a holding company that operates through the following forty-seven operating subsidiaries as of December 31, 2023: Subsidiary Principal Date Acquired / ALTN Ownership Country of Power Clouds S.r.l. SPV 31 March 2015 Solis Bond Company DAC Romania F.R.A.N. Energy Investment S.r.l. SPV 31 March 2015 Solis Bond Company DAC Romania PC-Italia-01 S.r.l. Sub-Holding SPV 15 May 2015 AEG MH 02 Limited Italy Zonnepark Rilland B.V. SPV 20 December 2019 Solis Bond Company DAC Netherlands PC-Italia-03 S.r.l. SPV 1 July 2020 AEG MH 02 Limited Italy PC-Italia-04 S.r.l. SPV 15 July 2020 AEG MH 02 Limited Italy Solis Bond Company DAC Holding Company 16 October 2020 AEG JD 03 Limited Ireland ALT US 03, LLC LLC Acquired 15 December 2020 ALT US 03 LLC USA Alternus Energy Americas Inc. Holding Company 10 May 2021 Alternus Energy Group Pl USA LJG Green Source Energy Beta S.r.l SPV 29 July 2021 Solis Bond Company DAC Romania Ecosfer Energy S.r.l. SPV 30 July 2021 Solis Bond Company DAC Romania Lucas EST S.r.l. SPV 30 July 2021 Solis Bond Company DAC Romania Risorse Solari I S.r.l. SPV 28 September 2019 AEG MH 02 Limited Italy Risorse Solari III S.r.l. SPV 3 August 2021 AEG MH 02 Limited Italy Alternus Iberia S.L. SPV 4 August 2021 AEG MH 02 Limited Spain Solarpark Samas Sp. z o.o. SPV 31 August 2021 Solis Bond Company DAC Poland AED Italia-01 S.r.l. SPV 22 October 2021 AEG MH 02 Limited Italy AED Italia-02 S.r.l. SPV 22 October 2021 AEG MH 02 Limited Italy AED Italia-03 S.r.l. SPV 22 October 2021 AEG MH 02 Limited Italy AED Italia-04 S.r.l. SPV 22 October 2021 AEG MH 02 Limited Italy AED Italia-05 S.r.l. SPV 22 October 2021 AEG MH 02 Limited Italy ALT US 01 LLC SPV 6 December 2021 Alternus Energy Americas Inc. USA Elektrownia PV Komorowo Sp. z o.o. SPV 22 December 2021 Solis Bond Company DAC Poland PV Zachod Sp. z o.o. SPV 22 December 2021 Solis Bond Company DAC Poland AEG MH 01 Limited Holding Company 8 March 2022 Alternus Lux 01 S.a.r.l. Ireland AEG MH 02 Limited Holding Company 8 March 2022 AEG JD 03 Limited Ireland ALT US 02 LLC Holding Company 8 March 2022 Alternus Energy Americas Inc. USA AEG JD 01 Limited Holding Company 16 March 2022 AEG MH 03 Limited Ireland AEG JD 03 Limited Holding Company 21 March 2022 Alternus Lux 01 S.a.r.l. Ireland RA01 Sp. z o.o. SPV 24 March 2022 Solis Bond Company DAC Poland Gardno Sp. z o.o. SPV 24 March 2022 Solis Bond Company DAC Poland Gardno2 Sp. z o.o. SPV 24 March 2022 Solis Bond Company DAC Poland ALT US 03 LLC SPV 4 May 2022 Alternus Energy Americas Inc. USA Alt Spain 03, S.L.U. SPV 31 May 2022 Alt Spain Holdco S.L. Spain AEG MH 03 Limited Holding Company 10 June 2022 AEG MH 01 Limited Ireland Lightwave Renewables, LLC SPV Acquired 29 June 2022 ALT US 02 LLC USA Alt Spain Holdco, S.L.U. (NF Projects S.L) Holding Company Acquired 14 July 2022 AEG MH 02 Limited Spain AED Italia-06 S.r.l. SPV 2 August 2022 AEG MH 02 Limited Italy AED Italia-07 S.r.l. SPV 2 August 2022 AEG MH 02 Limited Italy AED Italia-08 S.r.l. SPV 5 August 2022 AEG MH 02 Limited Italy ALT US 04 LLC Holding Company 14 September 2022 Alternus Energy Americas Inc. USA Alternus LUX 01 S.a.r.l. Holding Company 5 October 2022 Alternus Energy Group Plc Luxembourg Alt Spain 04, S.L.U. SPV May 2022 Alt Spain Holdco, S.L.U. Spain Alt Alliance LLC Holding Company September 2023 Alternus Energy Amercias Inc. USA ALT US 05 LLC Holding Company September 2023 Alternus Energy Americas Inc. USA ALT US 06 LLC Holding Company October 2023 Alternus Energy Americas Inc. USA ALT US 07 LLC Holding Company November 2023 Alternus Energy Americas Inc. USA

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2023
Summary of Significant Accounting Policies [Abstract]
Schedule of the Company’s Revenues Disaggregated by Country	The following table shows the Company’s revenues disaggregated by country and contract type: Year Ended December 31, Revenue by Country 2023 2022 (in thousands) Italy $ 3,360 $ 3,354 Romania 16,608 13,710 United States 116 25 Total for continuing operations $ 20,084 $ 17,089 Discontinued Operations: Netherlands $ 2,840 $ 1,596 Poland 7,593 10,709 Total for discontinued operations $ 10,433 $ 12,305 Total for the period $ 30,517 $ 29,394 Year Ended December 31, Revenue by Offtake Type 2023 2022 (in thousands) Country Renewable Programs $ 2,972 $ 2,885 Green Certificates 10,548 9,409 Energy Offtake Agreements 6,560 4,795 Other Revenue 4 - Total for continuing operations $ 20,084 $ 17,089 Discontinued Operations: Country Renewable Programs $ 5,499 $ 6,994 Guarantees of Origin 129 44 Energy Offtake Agreements 4,805 5,267 Total for discontinued operations $ 10,433 $ 12,305 Total for the period $ 30,517 $ 29,394
Schedule of Diluted Net Loss Per Share	The following table sets forth the outstanding potentially dilutive securities that have been excluded in the calculation of diluted net loss per share because their inclusion would be anti-dilutive: Year Ended December 31, 2023 2022 (in thousands) Warrants 12,345 11,945 Total 12,345 11,945

Business Combination (Tables)

Business Combination (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Business Combination [Abstract]
Schedule of Common Stock Outstanding After the Closing of the Business Combination	The following table presents the total Common Stock outstanding immediately after the closing of the Business Combination: Number of Exchange of CLIN common stock subject to possible redemption that was not redeemed for Alternus Clean Energy Inc. common stock 127,142 Exchange of public share rights held by CLIN shareholders for Alternus Clean Energy Inc. common stock 2,300,000 Issuance of Alternus Clean Energy, Inc. common stock to promissory note holders 400,000 Exchange of CLIN Class A common stock held by CLIN Sponsor for Alternus Clean Energy Inc. common stock 8,556,667 Subtotal - Business Combination, net of redemptions 11,383,809 Issuance of shares under the FPA 1,496,234 Shares purchased by the accredited investor under the FPA 1,300,320 Issuance of Alternus Clean Energy Inc. common stock to Alternus Energy Group Plc. on the Closing Date 57,500,000 Issuance of Alternus Clean Energy Inc. common stock to the CLIN Sponsor as a holder of CLIN convertible notes on the Closing Date 225,000 Total – Alternus Clean Energy Inc. common stock outstanding as a result of the Business Combination, FPA, exchange of Acquired Subsidiaries’ shares for shares of Alternus Clean Energy Inc. and issuance of Alternus Clean Energy Inc. common stock the holder of CLIN convertible notes. 71,905,363	The following table presents the total Common Stock outstanding immediately after the closing of the Business Combination: Number of Exchange of CLIN common stock subject to possible redemption that was not redeemed for Alternus Clean Energy Inc. common stock 127,142 Exchange of public share rights held by CLIN shareholders for Alternus Clean Energy Inc. common stock 2,300,000 Issuance of Alternus Clean Energy, Inc. common stock to promissory note holders 400,000 Exchange of CLIN Class A common stock held by CLIN Sponsor for Alternus Clean Energy Inc. common stock 8,556,667 Subtotal - Business Combination, net of redemptions 11,383,809 Issuance of shares under the FPA 1,496,234 Shares purchased by the accredited investor under the FPA 1,300,320 Issuance of Alternus Clean Energy Inc. common stock to Alternus Energy Group Plc. on the Closing Date 57,500,000 Issuance of Alternus Clean Energy Inc. common stock to the CLIN Sponsor as a holder of CLIN convertible notes on the Closing Date 225,000 Total – Alternus Clean Energy Inc. common stock outstanding as a result of the Business Combination, FPA, exchange of Acquired Subsidiaries’ shares for shares of Alternus Clean Energy Inc. and issuance of Alternus Clean Energy Inc. common stock the holder of CLIN convertible notes. 71,905,363

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Fair Value Measurements [Abstract]
Schedule of Balances of the Forward Purchase Agreement with Significant Unobservable Inputs	As of March 31, 2024, the Forward Purchase Agreement value was $0, as presented below: Fair Value Measurement Level 1 Level 2 Level 3 Total Forward Purchase Agreement - - - - Total $ - $ - $ - $ -	The following table presents balances of the forward purchase agreement with significant unobservable inputs (Level 3) as of December 31, 2023, in thousand: Fair Value Measurement Level 1 Level 2 Level 3 Total Forward Purchase Agreement - - 483 483 Total $ - $ - $ 483 $ 483
Schedule of Changes of the Forward Purchase Agreement with Significant Unobservable Inputs	The following table presents changes of the forward purchase agreement with significant unobservable inputs (Level 3) as of March 31, 2024, in thousand: Forward Purchase Agreement Balance at January 1, 2023 $ - Recognition of Forward Purchase Agreement Asset 17,125 Change in fair value (16,642 ) Balance at December 31, 2023 483 Change in fair value (483 ) Balance at March 31, 2024 $ -	The following table presents changes of the forward purchase agreement with significant unobservable inputs (Level 3) for the year ended December 31, 2023, in thousand: Forward Purchase Agreement Asset Balance at January 1, 2023 $ - Recognition of Forward Purchase Agreement Asset 17,125 Change in fair value (16,642 ) Balance at December 31, 2023 $ 483
Schedule of the Forward Purchase Agreement Using a Monte Carlo Simulation Valuation Model	The Company measures the forward purchase agreement using a Monte Carlo simulation valuation model using the following assumptions: Forward Purchase Agreement Risk-free rate 4.5 % Underlying stock price $ 0.43 Expected volatility 92.7 % Term 2.73 years Dividend yield 0 %	The Company measures the forward purchase agreement using a Monte Carlo simulation valuation model using the following assumptions: Forward Purchase Agreement Asset Rik-free rate 4% Underlying stock price $1.50 Expected volatility 75% Term 2.98 years Dividend yield 0%

Accounts Receivable (Tables)

Accounts Receivable (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Accounts Receivable [Abstract]
Schedule of Accounts Receivables and Unbilled Energy Incentives	Accounts receivables and unbilled energy incentives consist of the following (in thousands): March 31 December 31 2024 2023 (in thousands) Accounts receivable $ 2,119 $ 651 Unbilled energy incentives earned 6,048 5,607 Total $ 8,167 $ 6,258	Accounts receivables, and unbilled energy incentives consist of the following (in thousands): Year Ended December 31, 2023 2022 (in thousands) Accounts receivable $ 651 $ 3,335 Unbilled energy incentives earned 5,607 4,954 Total $ 6,258 $ 8,289

Prepaid Expenses and Other Cu_2

Prepaid Expenses and Other Current Assets (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Prepaid Expenses and Other Current Assets [Abstract]
Schedule of Prepaid Expenses and Other Current Assets	Other receivable, prepaid expenses, and other current assets consist of the following (in thousands): March 31 December 31 2024 2023 (in thousands) Prepaid expenses and other current assets $ 2,501 $ 2,602 Accrued revenue - 6 Other receivable 522 736 Total $ 3,023 $ 3,344	Other receivable, prepaid expenses and other current assets consist of the following (in thousands): Year Ended December 31, 2023 2022 (in thousands) Prepaid expenses and other current assets $ 2,602 $ 328 Accrued revenue 6 294 Other receivable 736 860 Total $ 3,344 $ 1,482

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Property and Equipment, Net [Abstract]
Schedule of Property and Equipment	The components of property and equipment, net were as follows at March 31, 2024 and December 31, 2023 (in thousands): March 31 December 31 2024 2023 (in thousands) Solar energy facilities $ 55,737 $ 55,318 Land 500 511 Software and computers 6 - Furniture and fixtures 207 210 Asset retirement 164 168 Construction in progress 12,705 12,421 Total property and equipment 69,319 68,628 Less: Accumulated depreciation (7,714 ) (7,326 ) Total $ 61,605 $ 61,302	The components of property and equipment, net were as follows at December 31 (in thousands): Year Ended December 31, 2023 2022 (in thousands) Solar energy facilities $ 55,318 $ 75,009 Building - 107 Land 511 497 Furniture and fixtures 210 49 Asset retirement 168 341 Construction in progress 12,421 3,093 Total property and equipment 68,628 79,096 Less: Accumulated depreciation (7,326 ) (10,143 ) Total $ 61,302 $ 68,953

Capitalized Development Cost _2

Capitalized Development Cost and Other Long-Term Assets (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Capitalized Development Cost and Other Long-Term Assets [Abstract]
Schedule of Capitalized Cost and Other Long-Term Assets	Capitalized cost and other long-term assets consisted of the following (in thousands): March 31 December 31 2024 2023 (in thousands) Capitalized development cost $ 6,351 $ 6,216 Other receivables 1,000 1,483 Total $ 7,351 $ 7,699	Capitalized cost and other long-term assets consisted of the following (in thousands): Year Ended December 31, 2023 2022 (in thousands) Capitalized development cost $ 6,216 $ 2,146 Other receivables 1,483 - Total $ 7,699 $ 2,146

Accounts Payable (Tables)

Accounts Payable (Tables)	12 Months Ended
	Dec. 31, 2023
Accounts Payable [Abstract]
Schedule of Accounts Payable Represent Amounts Owned to Suppliers of Goods and Services	Accounts payable represent amounts owed to suppliers of goods and services that the Group has consumed through operations. Accounts payable consist of the following (in thousands): Year Ended December 31, 2023 2022 (in thousands) Accounts payable $ 5,084 $ 1,138 Total $ 5,084 $ 1,138

Deferred Income (Tables)

Deferred Income (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Deferred Income [Abstarct]
Schedule of Deferred Income	Deferred income relates to income related to Green Certificates from Romania that have been received but not sold. Deferred income consists of the following (in thousands): Activity Deferred income – Balance January 1, 2023 $ 4,954 Green certificates received 10,663 Green certificates sold (10,169 ) Foreign exchange gain/(loss) 159 Deferred income – Balance December 1, 2023 $ 5,607 Green certificates received 2,030 Green certificates sold (1,468 ) Foreign exchange gain/(loss) (121 ) Deferred income – Balance March 31, 2024 $ 6,048	Deferred income relates to income related to Green Certificates from Romania that have been received but not sold. Deferred income consists of the following (in thousands): Activity Deferred income – Balance January 1, 2022 $ 3,139 Green certificates received 10,729 Green certificates sold (8,849 ) Foreign exchange gain/(loss) (65 ) Deferred income – Balance December 1, 2022 $ 4,954 Green certificates received 10,663 Green certificates sold (10,169 ) Foreign exchange gain/(loss) 159 Deferred income – Balance December 31, 2023 $ 5,607

Accrued Liabilities (Tables)

Accrued Liabilities (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Accrued Liabilities [Abstract]
Schedule of Accrued Liabilities	Accrued expenses relate to various accruals for the Company. Accrued interest represents the interest in debt not paid in the three months ended March 31, 2024 and in the year ended December 31, 2023. Accrued liabilities consist of the following (in thousands): March 31 December 31 2024 2023 (in thousands) Accrued legal $ 7,258 $ 8,684 Accrued interest 6,294 5,516 Accrued financing cost 2,397 3,537 Accrued construction expense 363 2,134 Accrued transaction cost - business combination 261 1,527 Accrued audit fees 150 800 Accrued payroll 215 148 Other accrued expenses 2,094 2,064 Total $ 19,032 $ 24,410	Accrued expenses relate to various accruals for the Company. Accrued interest represents the interest in debt not paid in the year ended December 31, 2023 and 2022. Accrued liabilities consist of the following (in thousands): Year Ended December 31, 2023 2022 (in thousands) Accrued legal $ 8,684 $ - Accrued interest 5,516 1,992 Accrued financing cost 3,537 - Accrued construction expense 2,134 - Accrued transaction cost - business combination 1,527 - Accrued audit fees 800 - Accrued payroll 148 501 Other accrued expenses 2,064 978 Total $ 24,410 $ 3,471

Taxes Recoverable and Payable (

Taxes Recoverable and Payable (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Taxes Recoverable and Payable [Abstract]
Schedule of Taxes Recoverable and Payable	Taxes recoverable and payable consist of VAT taxes payable and receivable from various European governments through group transactions in these countries. Taxes recoverable consist of the following (in thousands): March 31 December 31 2024 2023 (in thousands) Taxes recoverable $ 683 $ 631 Less: Taxes payable (13 ) (14 ) Total $ 670 $ 617	Taxes recoverable and payable consist of VAT taxes payable and receivable from various European governments through group transactions in these countries. Taxes recoverable consist of the following (in thousands): Year Ended December 31, 2023 2022 (in thousands) Taxes recoverable $ 631 $ 1,388 Less: Taxes payable (14 ) (616 ) Total $ 617 $ 772

Green Bonds, Convertible and _2

Green Bonds, Convertible and Non-convertible Promissory Notes (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Green Bonds, Convertible and Non-convertible Promissory Notes [Abstract]
Schedule of Debt Balances	The following table reflects the total debt balances of the Company as March 31, 2024 and December 31, 2023 (in thousands): As of As of 2024 2023 (in thousands) Senior Secured Green Bonds $ 87,264 $ 166,122 Senior Secured debt and promissory notes secured 31,523 32,312 Total debt 118,787 198,434 Less current maturities (118,787 ) (198,434 ) Long term debt, net of current maturities $ - $ - Current Maturities $ 118,787 $ 198,434 Less current debt discount (908 ) (892 ) Current Maturities net of debt discount $ 117,879 $ 197,542	The following table reflects the total debt balances of the Company as December 31, 2023 and 2022 (in thousands): Year Ended December 31, 2023 2022 (in thousands) Senior Secured Green Bonds $ 166,122 $ 149,481 Senior Secured debt and promissory notes secured 32,312 13,486 Total debt 198,434 162,967 Less current maturities (198,434 ) - Long term debt, net of current maturities $ - $ 162,967 Current Maturities $ 198,434 $ - Less current debt discount (892 ) - Current Maturities net of debt discount $ 197,542 $ - Long-term maturities $ - $ 162,967 Less long-term debt discount - (4,272 ) Long-term maturities net of debt discount $ - $ 158,695

Leases (Tables)

Leases (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Leases [Abstract]
Schedule of Key Components of the Company's Operating Leases	The key components of the company’s operating leases were as follows (in thousands): March 31, December 31, 2024 2023 Operating Lease - Operating Cash Flows (Fixed Payments) 75 189 Operating Lease - Operating Cash Flows (Liability Reduction) 61 129 New ROU Assets - Operating Leases - 409 Weighted Average Lease Term - Operating Leases (years) 12.99 13.24 Weighted Average Discount Rate - Operating Leases 7.65 % 7.65 %	The key components of the company’s operating leases were as follows (in thousands): December 31, December 31, 2023 2022 Operating Lease - Operating Cash Flows (Fixed Payments) 189 99 Operating Lease - Operating Cash Flows (Liability Reduction) 129 54 New ROU Assets - Operating Leases 409 8,482 Weighted Average Lease Term - Operating Leases (years) 13.24 7.05 Weighted Average Discount Rate - Operating Leases 7.65 % 7.10 %
Schedule of Maturities of Lease Liabilities	Maturities of lease liabilities as of March 31, 2024 were as follows: (in thousands) Five-year lease schedule: 2024 Apr 1 – Dec 31 $ 154 2025 235 2026 241 2027 247 2028 215 Thereafter 2,021 Total lease payments 3,113 Less imputed interest (1,748 ) Total $ 1,365	Maturities of lease liabilities as of December 31, 2023 were as follows: (in thousands) Five-year lease schedule: 2024 $ 231 2025 237 2026 242 2027 248 2028 216 Thereafter 2,064 Total lease payments 3,238 Less imputed interest (1,811 ) Total $ 1,427

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Asset Retirement Obligations [Abstract]
Schedule of Asset Retirement Obligations	The discount rate used to estimate the present value of the expected future cash flows for the three months ended March 31, 2024 and the year ended December 31, 2023 was 7.7%. Activity ARO Liability - Balance January 1, 2023 $ 397 Additional obligations incurred - Disposals (235 ) Accretion expense 24 Foreign exchange gain/(loss) 11 ARO Liability - Balance December 31, 2023 $ 197 Additional obligations incurred - Disposals - Accretion expense 3 Foreign exchange gain/(loss) (4 ) ARO Liability -- March 31, 2024 $ 196	The Company’s AROs mostly relate to the retirement of solar park land or buildings. The discount rate used to estimate the present value of the expected future cash flows for the year ended December 31, 2023 and 2022 was 7.5% and 7.1%, respectively. Activity ARO Liability - Balance January 1, 2022 $ 411 Additional obligations incurred - Accretion expense 20 Foreign exchange gain/(loss) (34 ) ARO Liability - Balance December 31, 2022 $ 397 Additional obligations incurred - Disposals (235 ) Accretion expense 24 Foreign exchange gain/(loss) 11 ARO Liability -- December 31, 2023 $ 197

Development Cost (Tables)

Development Cost (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Development Cost [Abstract]
Schedule of Development Cost	Miscellaneous development cost $ 7 Total $ 7	The table below summarizes the development cost: Project 1 $ 10,162 Miscellaneous development cost 1,210 Total $ 11,372

Discontinued Operations Sold (T

Discontinued Operations Sold (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Discontinued Operations Sold [Abstract]
Schedule of Balances and Results of the Polish and Netherlands Disposal Groups	The sale of the Netherlands assets was finalized February 21, 2024 with a cash consideration of $7.1 million for all operating assets. As of As of Poland 2024 2023 (in thousands) Assets: Cash & cash equivalents $ 630 $ 630 Other current assets 442 443 Property, plant, and equipment, net 63,107 63,107 Operating leases, non-current - assets 5,923 5,923 Total assets held for sale $ 70,102 $ 70,103 Liabilities: Accounts payable $ 2,933 $ 2,935 Operating leases, current – liabilities 281 281 Other current liabilities 25 1,549 Operating leases, non-current - liabilities 5,798 5,798 Other non-current liabilities 985 985 Total liabilities to be disposed of $ 10,022 $ 11,548 Net assets held for sale $ 60,080 $ 58,555 As of As of Netherlands 2024 2023 (in thousands) Assets: Cash & cash equivalents $ 75 $ 155 Accounts receivable, net - 99 Other current assets 178 58 Property, plant, and equipment, net 7,669 7,845 Operating leases, non-current – assets 1,441 1,469 Other non-current assets 1,192 1,214 Total assets held for sale $ 10,555 $ 10,840 Liabilities: Accounts payable $ 945 $ 925 Operating leases, current – liabilities 55 55 Other current liabilities 95 430 Operating leases, non-current – liabilities 1,273 1,301 Total liabilities to be disposed of $ 2,368 $ 2,711 Net assets held for sale $ 8,187 $ 8,129	The balances and results of the Polish and Netherlands disposal groups are presented below: As of December 31 Poland 2023 2022 (in thousands) Assets: Cash & cash equivalents $ 630 $ 431 Other current assets 443 1,105 Property, plant, and equipment, net 63,107 69,656 Operating leases, non-current - assets 5,923 5,378 Total assets held for sale $ 70,103 $ 76,570 Liabilities: Accounts payable $ 2,935 $ 1,760 Operating leases, current – liabilities 281 233 Other current liabilities 1,549 1,157 Operating leases, non-current - liabilities 5,798 4,995 Other non-current liabilities 985 824 Total liabilities to be disposed of $ 11,548 $ 8,969 Net assets held for sale $ 58,555 $ 67,601 As of December 31, Netherlands 2023 2022 (in thousands) Assets: Cash & cash equivalents $ 155 $ 13 Accounts receivable, net 99 487 Other current assets 58 82 Property, plant, and equipment, net 7,845 7,984 Operating leases, non-current – assets 1,469 1,438 Other non-current assets 1,214 1,176 Total assets held for sale $ 10,840 $ 11,180 Liabilities: Accounts payable $ 925 $ 23 Operating leases, current – liabilities 55 52 Other current liabilities 430 235 Operating leases, non-current – liabilities 1,301 1,312 Total liabilities to be disposed of $ 2,711 $ 1,622 Net assets held for sale $ 8,129 $ 9,558
Schedule of Recognized in Discontinued Operations in the Statement of Profit or Loss	In accordance with ASC 360, the company removed the disposal group and recognized a loss of $1.3 million upon the sale, of which $0.5 million were costs associated with the sale. Three Months Ended Poland 2024 2023 (in thousands) Revenues $ 106 $ 1,105 Operating Expenses Cost of revenues (101 ) (936 ) Depreciation, amortization, and accretion (123 ) (609 ) Gain on disposal of asset 3,484 - Total operating expenses 3,260 (1,545 ) Income/(loss) from discontinued operations 3,366 (440 ) Other income/(expense): Interest expense (688 ) (1,224 ) Total other expenses $ (688 ) $ (1,224 ) Income/(Loss) before provision for income taxes $ 2,678 (1,664 ) Net income/(loss) from discontinued operations $ 2,678 $ (1,664 ) Impact of discontinued operations on EPS Net income/(loss) attributable to common stockholders, basic $ 2,678 $ (1,664 ) Net income/(loss) attributable to common stockholders, diluted 2,678 (1,664 ) Net income/(loss) per share attributable to common stockholders, basic $ 0.04 $ (0.03 ) Net income/(loss) per share attributable to common stockholders, diluted 0.04 (0.03 ) Weighted-average common stock outstanding, basic 65,077,094 57,500,000 Weighted-average common stock outstanding, diluted 65,077,094 57,500,000 Three Months Ended Netherlands 2024 2023 (in thousands) Revenues $ 16 $ 202 Operating Expenses Cost of revenues (115 ) (61 ) Depreciation, amortization, and accretion (57 ) (126 ) Loss on disposal of asset (1,334 ) - Total operating expenses (1,506 ) (187 ) Income/(loss) from discontinued operations (1,490 ) 15 Other income/(expense): Interest expense (113 ) (248 ) Total other expenses $ (113 ) $ (248 ) Loss before provision for income taxes $ (1,603 ) $ (233 ) Net loss from discontinued operations $ (1,603 ) $ (233 ) Impact of discontinued operations on EPS Net loss attributable to common stockholders, basic $ (1,603 ) $ (233 ) Net loss attributable to common stockholders, diluted (1,603 ) (233 ) Net loss per share attributable to common stockholders, basic $ (0.02 ) $ (0.00 ) Net loss per share attributable to common stockholders, diluted (0.02 ) (0.00 ) Weighted-average common stock outstanding, basic 65,077,094 57,500,000 Weighted-average common stock outstanding, diluted 65,077,094 57,500,000	Year Ended December 31, Poland 2023 2022 (in thousands) Revenues $ 7,593 $ 10,709 Operating Expenses Cost of revenues (3,768 ) (4,104 ) Depreciation, amortization, and accretion (2,563 ) (2,482 ) Loss on disposal of asset (130 ) - Total operating expenses (6,461 ) (6,586 ) Income from discontinued operations 1,132 4,123 Other income/(expense): Impairment loss recognized on the remeasurement to fair value less costs to sell (11,766 ) - Interest expense (5,650 ) (3,893 ) Other expense (157 ) (30 ) Total other expenses $ (17,573 ) $ (3,923 ) Income/(Loss) before provision for income taxes $ (16,441 ) 200 Income taxes - (21 ) Net income/(loss) from discontinued operations $ (16,441 ) $ 179 Impact of discontinued operations on EPS Net income/(loss) attributable to common stockholders, basic $ (16,441 ) $ 179 Net income/(loss) attributable to common stockholders, diluted (16,441 ) 179 Net income/(loss) per share attributable to common stockholders, basic $ (0.28 ) $ 0.00 Net income/(loss) per share attributable to common stockholders, diluted 0.00 0.00 Weighted-average common stock outstanding, basic 57,862,598 57,500,000 Weighted-average common stock outstanding, diluted 57,862,598 57,500,000 Year Ended December 31, Netherlands 2023 2022 (in thousands) Revenues $ 2,840 $ 1,596 Operating Expenses Cost of revenues (450 ) (368 ) Depreciation, amortization, and accretion (400 ) (500 ) Loss on disposal of asset (7 ) - Total operating expenses (857 ) (868 ) Income from discontinued operations 1,983 728 Other income/(expense): Interest expense (1,131 ) (787 ) Other expense (62 ) - Total other expenses $ (1,193 ) $ (787 ) Income/(Loss) before provision for income taxes $ 790 $ (59 ) Income taxes (161 ) - Net income/(loss) from discontinued operations $ 629 $ (59 ) Impact of discontinued operations on EPS Net income/(loss) attributable to common stockholders, basic $ 629 $ (59 ) Net income/(loss) attributable to common stockholders, diluted 629 (59 ) Net income/(loss) per share attributable to common stockholders, basic $ 0.01 $ (0.00 ) Net income/(loss) per share attributable to common stockholders, diluted 0.01 (0.00 ) Weighted-average common stock outstanding, basic 57,862,598 57,500,000 Weighted-average common stock outstanding, diluted 57,862,598 57,500,000

Italy Sale Disclosure (Tables)

Italy Sale Disclosure (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Italy Sale Disclosure [Abstract]
Schedule of Remaining Balances and Results of the Italian Assets	The remaining balances and results of the Italian assets not disposed are presented below: As of Year Ended Italy 2024 2023 (in thousands) Assets: Cash & cash equivalents $ 87 $ 100 Other current assets 330 338 Other non-current assets 3,966 3,819 Total assets $ 4,383 $ 4,257 Liabilities: Accounts payable $ 17 $ 21 Other current liabilities 569 578 Total liabilities $ 586 $ 599 Net assets $ 3,797 $ 3,658 Three Months Ended Italy 2024 2023 (in thousands) Revenues $ - $ 655 Operating Expenses Cost of revenues - (262 ) Selling, general, and administrative (8 ) (42 ) Depreciation, amortization, and accretion - (410 ) Total operating expenses (8 ) (714 ) Loss from discontinued operations (8 ) (59 ) Other income/(expense): Other expense - (36 ) Total other expenses $ - $ (36 ) Loss before provision for income taxes $ (8 ) $ (95 ) Income taxes - - Net loss from discontinued operations $ (8 ) $ (95 ) Impact on EPS Net loss attributable to common stockholders, basic $ (8 ) $ (95 ) Net loss attributable to common stockholders, diluted (8 ) (95 ) Net loss per share attributable to common stockholders, basic $ (0.00 ) $ (0.00 ) Net loss per share attributable to common stockholders, diluted (0.00 ) (0.00 ) Weighted-average common stock outstanding, basic 65,077,094 57,500,000 Weighted-average common stock outstanding, diluted 65,077,094 57,500,000	The balances and results of the Italian disposal group are presented below: As of Year Ended Italy 2023 2022 (in thousands) Assets: Cash & cash equivalents $ 100 $ 295 Accounts receivable, net - 932 Other current assets 338 1,030 Property, plant, and equipment, net - 21,735 Operating leases, non-current - assets - 4 Other non-current assets 3,819 800 Total assets held for sale $ 4,257 $ 24,796 Liabilities: Accounts payable $ 21 $ 109 Other current liabilities 578 1,080 Other non-current liabilities - 216 Total liabilities to be disposed of $ 599 $ 1,405 Net assets held for sale $ 3,658 $ 23,391 Year Ended December 31, Italy 2023 2022 (in thousands) Revenues $ 3,360 $ 3,354 Operating Expenses Cost of revenues (1,204 ) (812 ) Selling, general, and administrative (69 ) (77 ) Depreciation, amortization, and accretion (1,638 ) (1,614 ) Loss on disposal of asset (5,501 ) - Total operating expenses (8,412 ) (2,503 ) Income/(Loss) from discontinued operations (5,052 ) 851 Other income/(expense): Other expense (15 ) - Other income - 22 Total other expenses $ (15 ) $ 22 Income/(Loss) before provision for income taxes $ (5,067 ) $ 873 Income taxes - - Net income/(loss) from discontinued operations $ (5,067 ) $ 873 Impact on EPS Net income/(loss) attributable to common stockholders, basic $ (5,067 ) $ 873 Net income/(loss) attributable to common stockholders, diluted (5,067 ) 873 Net income/(loss) per share attributable to common stockholders, basic $ (0.09 ) $ 0.02 Net income/(loss) per share attributable to common stockholders, diluted (0.09 ) 0.02 Weighted-average common stock outstanding, basic 57,862,598 57,500,000 Weighted-average common stock outstanding, diluted 57,862,598 57,500,000

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Shareholders' Equity (Tables) [Line Items]
Schedule of Common Stock were Issued and Outstanding	As of March 31, 2024, warrants to purchase up to 12,435,000 shares of common stock were issued and outstanding. Warrants Weighted Weighted Outstanding - December 31, 2022 11,945,000 $ 11.50 5.98 Issued during the quarter - - - Expired during the quarter - - - Outstanding – March 31, 2023 11,945,000 11.50 5.98 Exercisable – March 31, 2023 11,945,000 $ 11.50 5.98 Warrants Weighted Weighted Outstanding - December 31, 2023 12,345,000 $ 11.22 4.93 Issued during the quarter 90,000 0.01 0.03 Expired during the quarter - - - Outstanding – March 31, 2024 12,435,000 11.14 4.73 Exercisable – March 31, 2024 12,435,000 $ 11.14 4.73
Warrant [Member]
Shareholders' Equity (Tables) [Line Items]
Schedule of Common Stock were Issued and Outstanding		As of December 31, 2023, warrants to purchase up to 12,345,000 shares of common stock were issued and outstanding. Warrants Weighted Weighted Outstanding - January 31, 2022 11,945,000 $ 11.50 5.98 Issued during the year - - - Expired during the year - - - Outstanding - December 31, 2022 11,945,000 $ 11.50 5.98 Issued during the year 400,000 0.35 0.16 Expired during the year - - - Outstanding – December 31, 2023 12,345,000 11.22 4.93 Exercisable – December 31, 2023 12,345,000 $ 11.22 4.93

Segment and Geographic Inform_2

Segment and Geographic Information (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Segment and Geographic Information [Abstract]
Schedule of Geographic information related to the Company’s reportable segments	The following tables present information related to the Company’s reportable segments. Three Months Ended Revenue by Segment 2024 2023 (in thousands) Europe $ 2,086 $ 3,828 Europe – Discontinued Operations 123 18 United States 93 1,307 Total for the period $ 2,302 $ 5,153 Three Months Ended Operating Loss by Segment 2024 2023 (in thousands) Europe $ (2,908 ) $ (4,310 ) United States (4,675 ) (942 ) Total for the period $ (7,583 ) $ (5,252 ) As of As of Assets by Segment 2024 2023 (in thousands) Europe Fixed Assets $ 42,209 $ 125,600 Other Assets 20,735 36,728 Total for Europe $ 62,944 $ 162,328 United States Fixed Assets $ 6,556 $ 5,119 Other Assets 14,854 17,839 Total for US $ 21,410 $ 22,958 As of As of Liabilities by Segment 2024 2023 (in thousands) Europe Debt $ 99,686 $ 180,294 Other Liabilities 28,108 39,378 Total for Europe $ 127,794 $ 219,672 United States Debt $ 16,582 $ 17,247 Other Liabilities 11,697 11,621 Total for US $ 28,279 $ 28,868 Three Months Ended Revenue by Product Type 2024 2023 (in thousands) Country Renewable Programs (FIT) Europe $ 29 $ 1,248 US 93 18 Total for the period $ 122 $ 1,266 Green Certificates (FIT) Europe $ 1,575 $ 1,880 US - - Total for the period $ 1,575 $ 1,880 Energy Offtake Agreements (PPA) Europe $ 605 $ 2,007 United States - - Total for the period $ 605 $ 2,007 Three Months Ended EBITDA by Segment 2024 2023 (in thousands) Europe $ 2,258 $ 2,122 US (2,827 ) (857 ) Total for the period $ (569 ) $ 1,265 Three Months Ended EBITDA Reconciliation to Net Loss 2024 2023 (in thousands) Europe EBITDA $ 2,258 $ 2,122 Depreciation, amortization, and accretion (699 ) (1,574 ) Interest expense (4,466 ) (4,858 ) Income taxes - - Net Loss $ (2,907 ) $ (4,310 ) US EBITDA $ (2,827 ) $ (857 ) Depreciation, amortization, and accretion (49 ) (2 ) Interest expense (1,317 ) (83 ) Income taxes - - Valuation on FPA Asset (483 ) - Net Loss $ (4,676 ) $ (942 ) Consolidated Net Loss $ (7,583 ) $ (5,252 )	The following tables present information related to the Company’s reportable segments. Year Ended December 31, Revenue by Segment 2023 2022 (in thousands) Europe $ 30,401 $ 29,368 Europe – Discontinued Operations (10,433 ) (12,305 ) United States 116 26 Total for the period $ 20,084 $ 17,089 Year Ended December 31, Operating Loss by Segment 2023 2022 (in thousands) Europe $ (46,301 ) $ (14,978 ) United States (23,163 ) (3,470 ) Total for the period $ (69,464 ) $ (18,448 ) Year Ended December 31, Assets by Segment 2023 2022 (in thousands) Europe Fixed Assets $ 125,600 $ 141,862 Other Assets 36,728 31,218 Total for Europe $ 162,328 $ 173,080 United States Fixed Assets $ 5,119 $ 599 Other Assets 17,839 4,636 Total for US $ 22,958 $ 5,235 Year Ended December 31, Liabilities by Segment 2023 2022 (in thousands) Europe Debt $ 180,294 $ 155,896 Other Liabilities 39,378 19,221 Total for Europe $ 219,672 $ 175,117 United States Debt $ 17,247 $ 2,793 Other Liabilities 11,621 2,987 Total for US $ 28,868 $ 5,780 Year Ended December 31, Revenue by Product Type 2023 2022 (in thousands) Country Renewable Programs (FIT) Europe $ 8,356 $ 9,854 US - - Total for the period $ 8,356 $ 9,854 Green Certificates (FIT) Europe $ 10,677 $ 9,452 US - - Total for the period $ 10,677 $ 9,452 Energy Offtake Agreements (PPA) Europe $ 11,368 $ 10,062 United States 116 26 Total for the period $ 11,484 $ 10,088 Year Ended December 31, Geographic Information by Segment 2023 2022 (in thousands) Europe Revenue $ 30,401 $ 29,368 Revenue – Discontinued Operations $ (10,433 ) $ (12,305 ) Long-lived assets $ 162,328 $ 173,080 United States Revenue $ 116 $ 26 Long-lived assets $ 22,958 $ 5,235 Consolidated Revenue $ 30,517 $ 29,394 Revenue – Discontinued Operations $ (10,433 ) $ (12,305 ) Long-lived assets $ 185,286 $ 178,315 Year Ended December 31, EBITDA by Segment 2023 2022 (in thousands) Europe $ 6,874 $ 6,537 US (4,560 ) (3,370 ) Total for the period $ 2,314 $ 3,167 Year Ended December 31, EBITDA Reconciliation to Net Loss 2023 2022 (in thousands) Europe EBITDA $ 6,874 $ 6,537 Depreciation, amortization, and accretion (6,563 ) (6,617 ) Interest expense (23,453 ) (14,876 ) Income taxes (161 ) (21 ) Solis Bond Waiver (11,766 ) - Impairment loss recognized on the remeasurement to fair value less costs to sell (11,232 ) - Net Loss $ (46,301 ) $ (14,977 ) US EBITDA $ (4,560 ) $ (3,370 ) Depreciation, amortization, and accretion (57 ) (42 ) Interest expense (1,889 ) (59 ) Income taxes (15 ) - Valuation on FPA Asset (16,642 ) - Net Loss $ (23,163 ) $ (3,471 ) Consolidated Net Loss $ (69,464 ) $ (18,448 )

Income Tax Provision (Tables)

Income Tax Provision (Tables)	12 Months Ended
	Dec. 31, 2023
Income Tax Provision [Abstract]
Schedule of Relationship Between Tax expense and Accounting Profit	Explanation of the relationship between tax expense and accounting profit: Year Ended December 31, 2023 2022 (in thousands) Income before taxes $ (53,637 ) $ (18,569 ) Tax at the applicable rate of 21% (11,263 ) (3,899 ) State income taxes, net of federal benefit - - Permanent items 5,852 1,439 Tax effect of differences in foreign tax rates 2,622 2,046 Other 302 (140 ) Change in valuation allowance 2,502 554 Actual income tax expense (benefit) $ 15 $ -
Schedule of Significant Portions of the Net Deferred Tax Assets	The tax effects of temporary difference and carryforwards that give rise to significant portions of the net deferred tax assets were as follows: Year Ended December 31, 2023 2022 (in thousands) Deferred tax assets: Net operating losses $ 1,329 $ 1,249 Interest expense carryforward 4,343 1,948 Lease liabilities 312 207 Total deferred tax assets 5,984 3,404 Deferred tax asset valuation allowance (5,693 ) (3,203 ) Net deferred tax assets 291 201 Deferred tax liabilities: Other - (1 ) Right-of-use asset (291 ) (200 ) Total deferred tax liabilities (291 ) (201 ) Net deferred taxes $ - $ -

Related Party (Tables)

Related Party (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Related Party [Abstract]
Schedule of Transactions with Directors	This agreement has a five year initial term and automatically extends for additional one year terms unless otherwise unilaterally terminated. Three Months Ended Transactions with Directors 2024 2023 (in thousands) Loan from Vestco, a related party to Board member and CEO Vincent Browne $ - $ 210 Total $ - $ 210	This agreement has a five year initial term and automatically extends for additional one year terms unless otherwise unilaterally terminated. Year Ended December 31, Transactions with Directors 2023 2022 (in thousands) Loan from Vestco, a related party to Board member and CEO Vincent Browne $ 210 $ - Final payment made to Vestco on November 16, 2023 (210 ) - Total $ - $ -
Schedule of Director's Renumeration	Three Months Ended Director’s remuneration 2024 2023 (in thousands) Remuneration in respect of services as directors $ 362 $ 74 Remuneration in respect to long term incentive schemes - - Total $ 362 $ 74	Year Ended December 31, Director’s remuneration 2023 2022 (in thousands) Remuneration in respect of services as directors $ 606 $ 315 Remuneration in respect to long term incentive schemes - - Total $ 606 $ 315

Organization and Formation (Det

Organization and Formation (Details) - $ / shares	3 Months Ended
	Mar. 31, 2024	Feb. 20, 2024	Jan. 23, 2024	Dec. 31, 2023	Oct. 12, 2022	Oct. 31, 2021
Organization and Formation [Line Items]
Share issued	2,796,554	100,000	81,301	2,796,554
Share price par value	$ 10	$ 0.35	$ 1.01	$ 10
Company incorporated date	May 14, 2021
Common Stock [Member]
Organization and Formation [Line Items]
Share issued				225,000
Common Stock [Member] | Business Combination Agreement [Member]
Organization and Formation [Line Items]
Share issued					57,500,000	57,500,000
Share price par value					$ 0.0001	$ 0.0001

Organization and Formation (D_2

Organization and Formation (Details) - Schedule of Operating Subsidiaries	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Power Clouds S.r.l. [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity	SPV	SPV
Date Acquired / Established	31 March 2015	31 March 2015
ALTN Ownership	Solis Bond Company DAC	Solis Bond Company DAC
Country of Operations	Romania	Romania
F.R.A.N. Energy Investment S.r.l. [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity	SPV	SPV
Date Acquired / Established	31 March 2015	31 March 2015
ALTN Ownership	Solis Bond Company DAC	Solis Bond Company DAC
Country of Operations	Romania	Romania
PC-Italia-01 S.r.l. [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity	Sub-Holding SPV	Sub-Holding SPV
Date Acquired / Established	15 May 2015	15 May 2015
ALTN Ownership	AEG MH 02 Limited	AEG MH 02 Limited
Country of Operations	Italy	Italy
Zonnepark Rilland B.V. [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity		SPV
Date Acquired / Established		20 December 2019
ALTN Ownership		Solis Bond Company DAC
Country of Operations		Netherlands
PC-Italia-03 S.r.l. [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity	SPV	SPV
Date Acquired / Established	1 July 2020	1 July 2020
ALTN Ownership	AEG MH 02 Limited	AEG MH 02 Limited
Country of Operations	Italy	Italy
PC-Italia-04 S.r.l. [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity	SPV	SPV
Date Acquired / Established	15 July 2020	15 July 2020
ALTN Ownership	AEG MH 02 Limited	AEG MH 02 Limited
Country of Operations	Italy	Italy
Solis Bond Company DAC [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity	Holding Company	Holding Company
Date Acquired / Established	16 October 2020	16 October 2020
ALTN Ownership	AEG JD 03 Limited	AEG JD 03 Limited
Country of Operations	Ireland	Ireland
ALT US 03, LLC (Walking Horse Solar, LLC) [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity		LLC
Date Acquired / Established		Acquired 15 December 2020 (Est. 30 March 2023)
ALTN Ownership		ALT US 03 LLC
Country of Operations		USA
Alternus Energy Americas Inc. [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity	Holding Company	Holding Company
Date Acquired / Established	10 May 2021	10 May 2021
ALTN Ownership	Alternus Energy Group Pl	Alternus Energy Group Pl
Country of Operations	USA	USA
LJG Green Source Energy Beta S.r.l [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity	SPV	SPV
Date Acquired / Established	29 July 2021	29 July 2021
ALTN Ownership	Solis Bond Company DAC	Solis Bond Company DAC
Country of Operations	Romania	Romania
Ecosfer Energy S.r.l. [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity	SPV	SPV
Date Acquired / Established	30 July 2021	30 July 2021
ALTN Ownership	Solis Bond Company DAC	Solis Bond Company DAC
Country of Operations	Romania	Romania
Lucas EST S.r.l. [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity	SPV	SPV
Date Acquired / Established	30 July 2021	30 July 2021
ALTN Ownership	Solis Bond Company DAC	Solis Bond Company DAC
Country of Operations	Romania	Romania
Risorse Solari I S.r.l. [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity	SPV	SPV
Date Acquired / Established	28 September 2019	28 September 2019
ALTN Ownership	AEG MH 02 Limited	AEG MH 02 Limited
Country of Operations	Italy	Italy
Risorse Solari III S.r.l. [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity	SPV	SPV
Date Acquired / Established	3 August 2021	3 August 2021
ALTN Ownership	AEG MH 02 Limited	AEG MH 02 Limited
Country of Operations	Italy	Italy
Alternus Iberia S.L. [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity	SPV	SPV
Date Acquired / Established	4 August 2021	4 August 2021
ALTN Ownership	AEG MH 02 Limited	AEG MH 02 Limited
Country of Operations	Spain	Spain
Solarpark Samas Sp. z o.o. [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity		SPV
Date Acquired / Established		31 August 2021
ALTN Ownership		Solis Bond Company DAC
Country of Operations		Poland
AED Italia-01 S.r.l. [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity	SPV	SPV
Date Acquired / Established	22 October 2021	22 October 2021
ALTN Ownership	AEG MH 02 Limited	AEG MH 02 Limited
Country of Operations	Italy	Italy
AED Italia-02 S.r.l. [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity	SPV	SPV
Date Acquired / Established	22 October 2021	22 October 2021
ALTN Ownership	AEG MH 02 Limited	AEG MH 02 Limited
Country of Operations	Italy	Italy
AED Italia-03 S.r.l. [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity	SPV	SPV
Date Acquired / Established	22 October 2021	22 October 2021
ALTN Ownership	AEG MH 02 Limited	AEG MH 02 Limited
Country of Operations	Italy	Italy
AED Italia-04 S.r.l. [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity	SPV	SPV
Date Acquired / Established	22 October 2021	22 October 2021
ALTN Ownership	AEG MH 02 Limited	AEG MH 02 Limited
Country of Operations	Italy	Italy
AED Italia-05 S.r.l. [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity	SPV	SPV
Date Acquired / Established	22 October 2021	22 October 2021
ALTN Ownership	AEG MH 02 Limited	AEG MH 02 Limited
Country of Operations	Italy	Italy
ALT US 01 LLC [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity	SPV	SPV
Date Acquired / Established	6 December 2021	6 December 2021
ALTN Ownership	Alternus Energy Americas Inc.	Alternus Energy Americas Inc.
Country of Operations	USA	USA
Elektrownia PV Komorowo Sp. z o.o. [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity		SPV
Date Acquired / Established		22 December 2021
ALTN Ownership		Solis Bond Company DAC
Country of Operations		Poland
PV Zachod Sp. z o.o. [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity		SPV
Date Acquired / Established		22 December 2021
ALTN Ownership		Solis Bond Company DAC
Country of Operations		Poland
AEG MH 01 Limited [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity	Holding Company	Holding Company
Date Acquired / Established	8 March 2022	8 March 2022
ALTN Ownership	Alternus Lux 01 S.a.r.l.	Alternus Lux 01 S.a.r.l.
Country of Operations	Ireland	Ireland
AEG MH 02 Limited [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity	Holding Company	Holding Company
Date Acquired / Established	8 March 2022	8 March 2022
ALTN Ownership	AEG JD 03 Limited	AEG JD 03 Limited
Country of Operations	Ireland	Ireland
ALT US 02 LLC [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity	Holding Company	Holding Company
Date Acquired / Established	8 March 2022	8 March 2022
ALTN Ownership	Alternus Energy Americas Inc.	Alternus Energy Americas Inc.
Country of Operations	USA	USA
AEG JD 01 Limited [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity	Holding Company	Holding Company
Date Acquired / Established	16 March 2022	16 March 2022
ALTN Ownership	AEG MH 03 Limited	AEG MH 03 Limited
Country of Operations	Ireland	Ireland
AEG JD 03 Limited [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity		Holding Company
Date Acquired / Established		21 March 2022
ALTN Ownership		Alternus Lux 01 S.a.r.l.
Country of Operations		Ireland
RA01 Sp. z o.o. [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity		SPV
Date Acquired / Established		24 March 2022
ALTN Ownership		Solis Bond Company DAC
Country of Operations		Poland
Gardno Sp. z o.o. [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity		SPV
Date Acquired / Established		24 March 2022
ALTN Ownership		Solis Bond Company DAC
Country of Operations		Poland
Gardno2 Sp. z o.o. [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity		SPV
Date Acquired / Established		24 March 2022
ALTN Ownership		Solis Bond Company DAC
Country of Operations		Poland
ALT US 03 LLC [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity		SPV
Date Acquired / Established		4 May 2022
ALTN Ownership		Alternus Energy Americas Inc.
Country of Operations		USA
Alt Spain 03, S.L.U. [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity	SPV	SPV
Date Acquired / Established	31 May 2022	31 May 2022
ALTN Ownership	Alt Spain Holdco S.L.	Alt Spain Holdco S.L.
Country of Operations	Spain	Spain
AEG MH 03 Limited [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity	Holding Company	Holding Company
Date Acquired / Established	10 June 2022	10 June 2022
ALTN Ownership	AEG MH 01 Limited	AEG MH 01 Limited
Country of Operations	Ireland	Ireland
Lightwave Renewables, LLC [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity	SPV	SPV
Date Acquired / Established	29 June 2022	Acquired 29 June 2022 (Est. 17 December 2020)
ALTN Ownership	ALT US 02 LLC	ALT US 02 LLC
Country of Operations	USA	USA
Alt Spain Holdco, S.L.U. (NF Projects S.L) [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity		Holding Company
Date Acquired / Established		Acquired 14 July 2022 (Est. 31 July 2023)
ALTN Ownership		AEG MH 02 Limited
Country of Operations		Spain
AED Italia-06 S.r.l. [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity	SPV	SPV
Date Acquired / Established	2 August 2022	2 August 2022
ALTN Ownership	AEG MH 02 Limited	AEG MH 02 Limited
Country of Operations	Italy	Italy
AED Italia-07 S.r.l. [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity	SPV	SPV
Date Acquired / Established	2 August 2022	2 August 2022
ALTN Ownership	AEG MH 02 Limited	AEG MH 02 Limited
Country of Operations	Italy	Italy
AED Italia-08 S.r.l. [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity	SPV	SPV
Date Acquired / Established	5 August 2022	5 August 2022
ALTN Ownership	AEG MH 02 Limited	AEG MH 02 Limited
Country of Operations	Italy	Italy
ALT US 04 LLC (Dancing Horse, LLC) [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity		Holding Company
Date Acquired / Established		14 September 2022 (Est. 31 July 2023)
ALTN Ownership		Alternus Energy Americas Inc.
Country of Operations		USA
Alternus LUX 01 S.a.r.l. [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity	Holding Company	Holding Company
Date Acquired / Established	5 October 2022	5 October 2022
ALTN Ownership	Alternus Energy Group Plc	Alternus Energy Group Plc
Country of Operations	Luxembourg	Luxembourg
Alt Spain 04, S.L.U. [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity	SPV	SPV
Date Acquired / Established	May 2022	May 2022
ALTN Ownership	Alt Spain Holdco, S.L.U.	Alt Spain Holdco, S.L.U.
Country of Operations	Spain	Spain
Alt Alliance LLC [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity	Holding Company	Holding Company
Date Acquired / Established	September 2023	September 2023
ALTN Ownership	Alternus Energy Amercias Inc.	Alternus Energy Amercias Inc.
Country of Operations	USA	USA
ALT US 05 LLC [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity	Holding Company	Holding Company
Date Acquired / Established	September 2023	September 2023
ALTN Ownership	Alternus Energy Americas Inc.	Alternus Energy Americas Inc.
Country of Operations	USA	USA
ALT US 06 LLC [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity	Holding Company	Holding Company
Date Acquired / Established	October 2023	October 2023
ALTN Ownership	Alternus Energy Americas Inc.	Alternus Energy Americas Inc.
Country of Operations	USA	USA
ALT US 07 LLC (River Song Solar LLC) [Member]
Schedule of Operating Subsidiaries [Line Items]
Principal Activity		Holding Company
Date Acquired / Established		November 2023 (Est. December 2022)
ALTN Ownership		Alternus Energy Americas Inc.
Country of Operations		USA

Going Concern and Management'_2

Going Concern and Management's Plans (Details)					3 Months Ended			12 Months Ended
	May 01, 2024 USD ($)	May 01, 2024 EUR (€)	Feb. 14, 2024 USD ($)	Feb. 14, 2024 EUR (€)	Mar. 31, 2024 USD ($)	Mar. 31, 2024 EUR (€)	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2023 EUR (€)	Dec. 31, 2022 USD ($)	May 06, 2024 USD ($)	Apr. 30, 2024	Apr. 19, 2024	Mar. 31, 2024 EUR (€)	Mar. 20, 2024 $ / shares	Feb. 21, 2024 USD ($)	Feb. 21, 2024 EUR (€)	Jan. 18, 2024 USD ($)	Jan. 18, 2024 EUR (€)	Dec. 31, 2023 EUR (€)	Dec. 28, 2023 USD ($)	Dec. 28, 2023 EUR (€)	Mar. 31, 2022
Going Concern and Management's Plans (Details) [Line Items]
Net loss from continuing operations					$ (8,659,000)		$ (3,355,000)	$ (53,652,000)		$ (18,569,000)
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest							$ (3,400,000)			(18,600,000)
Shareholders’ equity/(deficit)					(71,700,000)			(63,300,000)		(2,600,000)
Unrestricted cash					$ 1,400,000			$ 4,600,000
Owned subsidiary, description					(i) the minimum Liquidity Covenant that requires the higher of €5.5 million or 5% of the outstanding Nominal Amount, (ii) the minimum Equity Ratio covenant of 25%, and (iii) the Leverage Ratio of NIBD/EBITDA to not be higher than 6.5 times for the year ended December 2021, 6.0 times for the year ended December 31, 2022 and 5.5 times for the period ending on the maturity date of the Bond. The Solis Bond carries a 3 months EURIBOR plus 6.5% per annum interest rate, and has quarterly interest payments, with a bullet payment to be paid on the Maturity Date.	(i) the minimum Liquidity Covenant that requires the higher of €5.5 million or 5% of the outstanding Nominal Amount, (ii) the minimum Equity Ratio covenant of 25%, and (iii) the Leverage Ratio of NIBD/EBITDA to not be higher than 6.5 times for the year ended December 2021, 6.0 times for the year ended December 31, 2022 and 5.5 times for the period ending on the maturity date of the Bond. The Solis Bond carries a 3 months EURIBOR plus 6.5% per annum interest rate, and has quarterly interest payments, with a bullet payment to be paid on the Maturity Date.
Percentage of Interest rate					7%							50%		7%
Distribution amount					$ 10,000,000				€ 10,000,000
Repayment amount (in Euro) | €						€ 10,000,000			€ 10,000,000
Maturity term								Jan. 06, 2024												Jan. 06, 2024
Percentage of bond holderes								1%	1%
Fees (in Euro) | €									€ 1,400,000
Owned amount					87,300,000					$ 159,000,000				€ 80,800,000						€ 150,000,000
Exercised options			$ 68,500,000	€ 59,100,000
Debt amount					$ 87,300,000
Total interest	50%	50%																					97%
Common stock closing bid price (in Dollars per share) | $ / shares															$ 1
Alternus Energy Group Plc [Member]
Going Concern and Management's Plans (Details) [Line Items]
Percentage of Interest rate					6.50%			6.50%						6.50%						6.50%
Solis Bond [Member]
Going Concern and Management's Plans (Details) [Line Items]
Owned subsidiary, description								(i) the minimum Liquidity Covenant that requires the higher of €5.5 million or 5% of the outstanding Nominal Amount, (ii) the minimum Equity Ratio covenant of 25%, and (iii) the Leverage Ratio of NIBD/EBITDA to not be higher than 6.5 times for the year ended December 2021, 6.0 times for the year ended December 31, 2022 and 5.5 times for the period ending on the maturity date of the Bond, January 6, 2024. The Solis Bond carries a 3 months EURIBOR plus 6.5% per annum interest rate, and has quarterly interest payments, with a bullet payment to be paid on January 6, 2024.	(i) the minimum Liquidity Covenant that requires the higher of €5.5 million or 5% of the outstanding Nominal Amount, (ii) the minimum Equity Ratio covenant of 25%, and (iii) the Leverage Ratio of NIBD/EBITDA to not be higher than 6.5 times for the year ended December 2021, 6.0 times for the year ended December 31, 2022 and 5.5 times for the period ending on the maturity date of the Bond, January 6, 2024. The Solis Bond carries a 3 months EURIBOR plus 6.5% per annum interest rate, and has quarterly interest payments, with a bullet payment to be paid on January 6, 2024.	(i) the minimum Liquidity Covenant that requires the higher of €5.5 million or 5% of the outstanding Nominal Amount, (ii) the minimum Equity Ratio covenant of 25%, and (iii) the Leverage Ratio of NIBD/EBITDA to not be higher than 6.5 times for the year ended December 2021, 6.0 times for the year ended December 31, 2022 and 5.5 times for the period ending on the maturity date of the Bond, January 6, 2024. The Solis Bond carries a 3 months EURIBOR plus 6.5% per annum interest rate, and has quarterly interest payments, with a bullet payment to be paid on January 6, 2024.
Share capital percentage																100%	100%	100%	100%		100%	100%
Share capital amount																$ 7,000,000	€ 6,500,000	$ 59,100,000	€ 54,400,000		$ 17,500,000	€ 15,800,000
Solis Bond trustee’s [Member]
Going Concern and Management's Plans (Details) [Line Items]
Owned subsidiary, description								On December 18, 2023, a representative group of the bondholders approved an extension of the temporary waivers and the maturity date of the Solis Bonds until January 31, 2024, with the right to further extend to February 29, 2024 at the Solis Bond trustee’s discretion, which was subsequently approved by a majority of the bondholders on January 3, 2024.	On December 18, 2023, a representative group of the bondholders approved an extension of the temporary waivers and the maturity date of the Solis Bonds until January 31, 2024, with the right to further extend to February 29, 2024 at the Solis Bond trustee’s discretion, which was subsequently approved by a majority of the bondholders on January 3, 2024.
Subsequent Event [Member]
Going Concern and Management's Plans (Details) [Line Items]
Percentage of Interest rate													7%
Exercised options			$ 68,500,000	€ 59,100,000,000,000
Subsequent Event [Member] | Solis Bond [Member]
Going Concern and Management's Plans (Details) [Line Items]
Share capital percentage																100%	100%	100%	100%
Share capital amount																$ 7,000,000	€ 6,500,000	$ 59,100,000	€ 54,400,000
Forecast [Member]
Going Concern and Management's Plans (Details) [Line Items]
Exercised options	$ 1,069,985	€ 1,000,000
Market value received											$ 35,000,000
Forecast [Member] | Market Value of Listed Securities [Member]
Going Concern and Management's Plans (Details) [Line Items]
Market value received											$ 35,000,000

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Details) € in Thousands, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2023 EUR (€)	Dec. 22, 2023	Feb. 29, 2016 USD ($)
Summary of Significant Accounting Policies [Line Items]
Percentage of shareholder			5%		5%	80%
Number of operating segments			2
Allowance for credit losses			$ 7	$ 0
Cash balance			2,500
Impairment loss			$ 11,800
Cash flow discount rate			7.30%	7.10%
Right of use assets	$ 1,303		$ 1,330	$ 1,004			$ 8,800
Associated liabilities							$ 8,700
Revenues from customers			11,200	14,200
Foreign currency translation adjustment	$ (1,232)	$ (104)	714	$ (991)
European Union [Member]
Summary of Significant Accounting Policies [Line Items]
Cash balance			105,841		€ 100,000
United States [Member]
Summary of Significant Accounting Policies [Line Items]
Cash balance			250,000
Europe [Member]
Summary of Significant Accounting Policies [Line Items]
Cash balance			$ 18,800
Solar Energy Facilities [Member]
Summary of Significant Accounting Policies [Line Items]
Useful life			35 years		35 years
Furniture and Fixtures [Member]
Summary of Significant Accounting Policies [Line Items]
Useful life			3 years		3 years
Software and Computer Equipment [Member] | Minimum [Member]
Summary of Significant Accounting Policies [Line Items]
Useful life			3 years		3 years
Software and Computer Equipment [Member] | Maximum [Member]
Summary of Significant Accounting Policies [Line Items]
Useful life			5 years		5 years
One Customer [Member] | Customer Concentration Risk [Member] | Revenue Benchmark [Member]
Summary of Significant Accounting Policies [Line Items]
Concentration of credit risk percentage			35%	29%
One Customer [Member] | Customer Concentration Risk [Member] | Accounts Receivable [Member]
Summary of Significant Accounting Policies [Line Items]
Concentration of credit risk percentage			23%
Three Customer [Member] | Customer Concentration Risk [Member] | Accounts Receivable [Member]
Summary of Significant Accounting Policies [Line Items]
Concentration of credit risk percentage			61%
Three Customer [Member] | Europe [Member] | Customer Concentration Risk [Member] | Accounts Receivable [Member]
Summary of Significant Accounting Policies [Line Items]
Concentration of credit risk percentage			61%
One Customer [Member] | Customer Concentration Risk [Member] | Revenue Benchmark [Member]
Summary of Significant Accounting Policies [Line Items]
Concentration of credit risk percentage			35%	29%
Customer [Member]
Summary of Significant Accounting Policies [Line Items]
Revenues from customers			$ 11,400	$ 9,700
Two Customers [Member] | Customer Concentration Risk [Member] | Revenue Benchmark [Member]
Summary of Significant Accounting Policies [Line Items]
Concentration of credit risk percentage			34%	42%

Summary of Significant Accoun_4

Summary of Significant Accounting Policies (Details) - Schedule of Disaggregated Revenues - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Schedule of Disaggregated Revenues [Line Items]
Revenue by Country, Total for continuing operations	$ 2,180	$ 3,846	$ 20,084	$ 17,089
Discontinued Operations:
Revenue by Country, Total for discontinued operations			10,433	12,305
Revenue by Country, Total for the period			30,517	29,394
Revenue by Offtake Type, Total for continuing operations			20,084	17,089
Discontinued Operations:
Revenue by Offtake Type, Total for discontinued operations			10,433	12,305
Revenue by Offtake Type, Total for the period			30,517	29,394
Italy [Member]
Schedule of Disaggregated Revenues [Line Items]
Revenue by Country, Total for continuing operations			3,360	3,354
Romania [Member]
Schedule of Disaggregated Revenues [Line Items]
Revenue by Country, Total for continuing operations			16,608	13,710
United States [Member]
Schedule of Disaggregated Revenues [Line Items]
Revenue by Country, Total for continuing operations			116	25
Netherlands [Member]
Discontinued Operations:
Revenue by Country, Total for discontinued operations			2,840	1,596
Poland [Member]
Discontinued Operations:
Revenue by Country, Total for discontinued operations			7,593	10,709
Country Renewable Programs [Member]
Discontinued Operations:
Revenue by Offtake Type, Total for continuing operations			2,972	2,885
Discontinued Operations:
Revenue by Offtake Type, Total for discontinued operations			5,499	6,994
Green Certificates [Member]
Discontinued Operations:
Revenue by Offtake Type, Total for continuing operations			10,548	9,409
Energy Offtake Agreements [Member]
Discontinued Operations:
Revenue by Offtake Type, Total for continuing operations			6,560	4,795
Discontinued Operations:
Revenue by Offtake Type, Total for discontinued operations			4,805	5,267
Other Revenue [Member]
Discontinued Operations:
Revenue by Offtake Type, Total for continuing operations			4
Guarantees of Origin [Member]
Discontinued Operations:
Revenue by Offtake Type, Total for discontinued operations			$ 129	$ 44

Summary of Significant Accoun_5

Summary of Significant Accounting Policies (Details) - Schedule of Diluted Net Loss Per Share - shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Schedule of Diluted Net Loss Per Share [Line Items]
Total	12,345	11,945
Warrants [Member]
Schedule of Diluted Net Loss Per Share [Line Items]
Total	12,345	11,945

Business Combination (Details)

Business Combination (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Business Combination (Details) [Line Items]
Business combination, consideration of right to receive of shares	23,000,000	23,000,000
Shares issued	81,396,664	71,905,363	57,500,000
Exercise price (in Dollars per share)		$ 0.01
Forward Purchase Agreement [Member]
Business Combination (Details) [Line Items]
Business combination, consideration of share issued	1,496,234	1,496,234
Proceeds received from business combination (in Dollars)	$ 5.1	$ 5.1
Promissory Note [Member]
Business Combination (Details) [Line Items]
Number of warrant purchase	300,000	300,000
Exercise price (in Dollars per share)	$ 0.01	$ 0.01
Secured Promissory Note Agreement [Member]
Business Combination (Details) [Line Items]
Number of warrant purchase	100,000	100,000
Exercise price (in Dollars per share)	$ 11.5	$ 11.5
Forward Purchase Agreement [Member]
Business Combination (Details) [Line Items]
Business Combination, Consideration Obligation of share purchase	2,796,554	2,796,554
Business Combination, Consideration maximum limit of share purchase	2,796,554	2,796,554
Number of share purchased	1,300,320	1,300,320
Common Stock [Member]
Business Combination (Details) [Line Items]
Business combination, consideration exchanged for shares	57,500,000	57,500,000
Shares issued	225,000	225,000
Class A Common Stock [Member]
Business Combination (Details) [Line Items]
Business combination, consideration exchanged for shares	2,300,000	2,300,000
Business combination, consideration of right to receive of shares	1	1
Common Stock Subject to Possible Redemption [Member]
Business Combination (Details) [Line Items]
Business combination, consideration exchanged for shares	127,142	127,142
Sponsor [Member] | Class A Common Stock [Member]
Business Combination (Details) [Line Items]
Business combination, consideration exchanged for shares	8,556,667	8,556,667

Business Combination (Details)

Business Combination (Details) - Schedule of Common Stock Outstanding After the Closing of the Business Combination - shares	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 22, 2008
Business Combination (Details) - Schedule of Common Stock Outstanding After the Closing of the Business Combination [Line Items]
Total common stock outstanding	81,396,664	71,905,363	57,500,000	71,905,363
Exchange of CLIN common stock subject to possible redemption that was not redeemed for Alternus Clean Energy Inc. common stock [Member]
Business Combination (Details) - Schedule of Common Stock Outstanding After the Closing of the Business Combination [Line Items]
Total common stock outstanding				127,142
Exchange of public share rights held by CLIN shareholders for Alternus Clean Energy Inc. common stock [Member]
Business Combination (Details) - Schedule of Common Stock Outstanding After the Closing of the Business Combination [Line Items]
Total common stock outstanding				2,300,000
Issuance of Alternus Clean Energy, Inc. common stock to promissory note holders [Member]
Business Combination (Details) - Schedule of Common Stock Outstanding After the Closing of the Business Combination [Line Items]
Total common stock outstanding				400,000
Exchange of CLIN Class A common stock held by CLIN Sponsor for Alternus Clean Energy Inc. common stock [Member]
Business Combination (Details) - Schedule of Common Stock Outstanding After the Closing of the Business Combination [Line Items]
Total common stock outstanding				8,556,667
Subtotal - Business Combination, net of redemptions [Member]
Business Combination (Details) - Schedule of Common Stock Outstanding After the Closing of the Business Combination [Line Items]
Total common stock outstanding				11,383,809
Issuance of shares under the FPA [Member]
Business Combination (Details) - Schedule of Common Stock Outstanding After the Closing of the Business Combination [Line Items]
Total common stock outstanding				1,496,234
Shares purchased by the accredited investor under the FPA [Member]
Business Combination (Details) - Schedule of Common Stock Outstanding After the Closing of the Business Combination [Line Items]
Total common stock outstanding				1,300,320
Issuance of Alternus Clean Energy Inc. common stock to Alternus Energy Group Plc. on the Closing Date [Member]
Business Combination (Details) - Schedule of Common Stock Outstanding After the Closing of the Business Combination [Line Items]
Total common stock outstanding				57,500,000
Issuance of Alternus Clean Energy Inc. common stock to the CLIN Sponsor as a holder of CLIN convertible notes on the Closing Date [Member]
Business Combination (Details) - Schedule of Common Stock Outstanding After the Closing of the Business Combination [Line Items]
Total common stock outstanding				225,000

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($)		3 Months Ended	12 Months Ended
	Dec. 10, 2023	Mar. 31, 2024	Dec. 31, 2023	Feb. 20, 2024	Jan. 23, 2024
Fair Value Measurements (Details) [Line Items]
Shares of common stock		2,796,554	2,796,554	100,000	81,301
Recycled shares	1,300,320
Additional shares	1,496,234
Total shares	2,796,554
Prepayment shortfall (in Dollars)		$ 500,000	$ 500,000
Closing price per share (in Dollars per share)		$ 10	$ 10	$ 0.35	$ 1.01
Sales rate		100%	100%
Reset price per share (in Dollars per share)		$ 10	$ 10
Forward purchase agreement (in Dollars)			$ 483,000
PIPE Subscription Agreement [Member]
Fair Value Measurements (Details) [Line Items]
Shares of common stock		1,300,320	1,300,320
Purchase Agreement [Member]
Fair Value Measurements (Details) [Line Items]
Forward purchase agreement (in Dollars)		$ 0

Fair Value Measurements (Deta_2

Fair Value Measurements (Details) - Schedule of Balances of the Forward Purchase Agreement with Significant Unobservable Inputs - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Fair Value Measurements (Details) - Schedule of Balances of the Forward Purchase Agreement with Significant Unobservable Inputs [Line Items]
Forward Purchase Agreement		$ 483
Total		483
Level 1 [Member]
Fair Value Measurements (Details) - Schedule of Balances of the Forward Purchase Agreement with Significant Unobservable Inputs [Line Items]
Forward Purchase Agreement
Total
Level 2 [Member]
Fair Value Measurements (Details) - Schedule of Balances of the Forward Purchase Agreement with Significant Unobservable Inputs [Line Items]
Forward Purchase Agreement
Total
Level 3 [Member]
Fair Value Measurements (Details) - Schedule of Balances of the Forward Purchase Agreement with Significant Unobservable Inputs [Line Items]
Forward Purchase Agreement		483
Total		$ 483

Fair Value Measurements (Deta_3

Fair Value Measurements (Details) - Schedule of Changes of the Forward Purchase Agreement with Significant Unobservable Inputs $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($)
Schedule of Changes of the Forward Purchase Agreement with Significant Unobservable Inputs [Abstract]
Balance
Recognition of Forward Purchase Agreement Asset	17,125
Change in fair value	(16,642)
Balance	$ 483

Fair Value Measurements (Deta_4

Fair Value Measurements (Details) - Schedule of the Forward Purchase Agreement Using a Monte Carlo Simulation Valuation Model - Forward Purchase Agreement Asset [Member]	Mar. 31, 2024	Dec. 31, 2023
Rik-free rate [Member]
Schedule of the Forward Purchase Agreement Using a Monte Carlo Simulation Valuation Model [Line Items]
Forward Purchase Agreement Asset Input	4.5%	4%
Underlying stock price [Member]
Schedule of the Forward Purchase Agreement Using a Monte Carlo Simulation Valuation Model [Line Items]
Forward Purchase Agreement Asset Input	$0.43	$1.50
Expected volatility [Member]
Schedule of the Forward Purchase Agreement Using a Monte Carlo Simulation Valuation Model [Line Items]
Forward Purchase Agreement Asset Input	92.7%	75%
Term [Member]
Schedule of the Forward Purchase Agreement Using a Monte Carlo Simulation Valuation Model [Line Items]
Forward Purchase Agreement Asset Input	2.73 years	2.98 years
Dividend yield [Member]
Schedule of the Forward Purchase Agreement Using a Monte Carlo Simulation Valuation Model [Line Items]
Forward Purchase Agreement Asset Input	0%	0%

Business Combination and Acqu_2

Business Combination and Acquisitions of Assets (Details) $ in Millions	1 Months Ended
	Mar. 24, 2022 USD ($)
Acquisition of RA01 Sp. Z.O.O. [Member]
Business Combination and Acquisitions of Assets (Details) [Line Items]
Purchase price	$ 1.1
Acquisition of Gardno Sp. Z.O.O. [Member]
Business Combination and Acquisitions of Assets (Details) [Line Items]
Purchase price	6.6
Acquisition of Gardno 2 Sp. Z.O.O. [Member]
Business Combination and Acquisitions of Assets (Details) [Line Items]
Purchase price	4.4
Property and Equipment [Member] | Acquisition of RA01 Sp. Z.O.O. [Member]
Business Combination and Acquisitions of Assets (Details) [Line Items]
Assets acquisition	1
Property and Equipment [Member] | Acquisition of Gardno Sp. Z.O.O. [Member]
Business Combination and Acquisitions of Assets (Details) [Line Items]
Assets acquisition	6.4
Property and Equipment [Member] | Acquisition of Gardno 2 Sp. Z.O.O. [Member]
Business Combination and Acquisitions of Assets (Details) [Line Items]
Assets acquisition	4.3
Other Assets [Member] | Acquisition of RA01 Sp. Z.O.O. [Member]
Business Combination and Acquisitions of Assets (Details) [Line Items]
Assets acquisition	0.1
Other Assets [Member] | Acquisition of Gardno Sp. Z.O.O. [Member]
Business Combination and Acquisitions of Assets (Details) [Line Items]
Assets acquisition	0.2
Other Assets [Member] | Acquisition of Gardno 2 Sp. Z.O.O. [Member]
Business Combination and Acquisitions of Assets (Details) [Line Items]
Assets acquisition	$ 0.1

Accounts Receivable (Details) -

Accounts Receivable (Details) - Schedule of Accounts Receivables and Unbilled Energy Incentives - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Schedule of Accounts Receivables and Unbilled Energy Incentives [Abstract]
Accounts receivable	$ 2,119	$ 651	$ 3,335
Unbilled energy incentives earned	6,048	5,607	4,954
Total	$ 8,167	$ 6,258	$ 8,289

Prepaid Expenses and Other Cu_3

Prepaid Expenses and Other Current Assets (Details) - Schedule of Prepaid Expenses and Other Current Assets - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Schedule of Prepaid Expenses and Other Current Assets [Abstract]
Prepaid expenses and other current assets	$ 2,501	$ 2,602	$ 328
Accrued revenue		6	294
Other receivable	522	736	860
Total	$ 3,023	$ 3,344	$ 1,482

Property and Equipment, Net (De

Property and Equipment, Net (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Property and Equipment, Net [Line Items]
Construction progress	$ 5.1	$ 0.6

Property and Equipment, Net (_2

Property and Equipment, Net (Details) - Schedule of Property and Equipment - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 69,319	$ 68,628	$ 79,096
Less: Accumulated depreciation	(7,714)	(7,326)	(10,143)
Total	61,605	61,302	68,953
Solar energy facilities [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	55,737	55,318	75,009
Building [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	500	511	107
Land [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	6	511	497
Furniture and fixtures [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	207	210	49
Asset retirement [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	164	168	341
Construction in progress [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 12,705	$ 12,421	$ 3,093

Capitalized Development Cost _3

Capitalized Development Cost and Other Long-Term Assets (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Capitalized Development Cost and Other Long-Term Assets (Details) [Line Items]
Security deposits	$ 1,000	$ 1,000
Purchase agreement		483
United States [Member]
Capitalized Development Cost and Other Long-Term Assets (Details) [Line Items]
Capitalized development cost	2,100	2,100
Europe [Member]
Capitalized Development Cost and Other Long-Term Assets (Details) [Line Items]
Capitalized development cost	$ 4,300	$ 4,100

Capitalized Development Cost _4

Capitalized Development Cost and Other Long-Term Assets (Details) - Schedule of Capitalized Cost and Other Long-Term Assets - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Schedule of Capitalized Cost and Other Long-Term Assets [Abstract]
Capitalized development cost	$ 6,351	$ 6,216	$ 2,146
Other receivables	1,000	1,483
Total	$ 7,351	$ 7,699	$ 2,146

Accounts Payable (Details) - Sc

Accounts Payable (Details) - Schedule of Accounts Payable Represent Amounts Owned to Suppliers of Goods and Services - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Schedule of Accounts Payable Represent Amounts Owned to Suppliers of Goods and Services [Abstract]
Accounts payable	$ 10,494	$ 5,084	$ 1,138
Total		$ 5,084	$ 1,138

Deferred Income (Details) - Sch

Deferred Income (Details) - Schedule of Deferred Income - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Schedule of Deferred Income [Abstract]
Deferred income beginning balance	$ 5,607	$ 4,954	$ 3,139
Green certificates received	2,030	10,663	10,729
Green certificates sold	(1,468)	(10,169)	(8,849)
Foreign exchange gain/(loss)	(121)	159	(65)
Deferred income ending balance	$ 6,048	$ 5,607	$ 4,954

Accrued Liabilities (Details) -

Accrued Liabilities (Details) - Schedule of Accrued Liabilities - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Schedule of Accrued Liabilities [Abstract]
Accrued legal	$ 7,258	$ 8,684
Accrued interest	6,294	5,516	1,992
Accrued financing cost	2,397	3,537
Accrued construction expense	363	2,134
Accrued transaction cost - business combination	261	1,527
Accrued audit fees	150	800
Accrued payroll	215	148	501
Other accrued expenses	2,094	2,064	978
Total	$ 19,032	$ 24,410	$ 3,471

Taxes Recoverable and Payable_2

Taxes Recoverable and Payable (Details) - Schedule of Taxes Recoverable and Payable - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Schedule of Taxes Recoverable and Payable [Abstract]
Taxes recoverable	$ 683	$ 631	$ 1,388
Less: Taxes payable	(13)	(14)	(616)
Total	$ 670	$ 617	$ 772

Green Bonds, Convertible and _3

Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Part 1 - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Nov. 30, 2021
Green Bonds, Convertible and Non-convertible Promissory Notes [Abstract]
Debt issuance cost		$ 4,100	$ 200	$ 11,800
Amortization of debt discounts	$ 700	$ 4,900	$ 3,900
Short-term debt maturity year		2024

Green Bonds, Convertible and _4

Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Part 2 - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended					3 Months Ended	12 Months Ended
	Dec. 21, 2022	Dec. 31, 2023	Oct. 31, 2023	Jul. 31, 2023	Jun. 30, 2022	May 31, 2022	Mar. 31, 2024	Dec. 31, 2023	May 31, 2024	Sep. 30, 2023	May 31, 2023	Feb. 28, 2023	Dec. 31, 2022
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Part 2 [Line Items]
Stated interest rate			0%				10%
Margin rate	0.50%
Working capital loan			$ 3,200
Loan amount										$ 3,600
Warrants to purchase shares (in Shares)		90,000						90,000
Exercisable price per share (in Dollars per share)		$ 0.01						$ 0.01
Repayment terms								5 year
Fair value		$ 86						$ 86
AEG MH02 [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Part 2 [Line Items]
Stated interest rate											18%	16%
Recognized interest								2,400
Principal outstanding balance		11,000						11,000					$ 10,700
ALT US 02 LLC [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Part 2 [Line Items]
Stated interest rate					2.50%
Maturity date					Jun. 29, 2023
Principal outstanding balance		4,300						4,300					$ 2,800
Promissory note					$ 5,900
ALT US 03, LLC [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Part 2 [Line Items]
Promissory note												$ 920
Senior secured debt, principal outstanding		717						717
32 MWp Solar PV Project [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Part 2 [Line Items]
Stated interest rate				24%
Maturity date				Feb. 29, 2024
Principal outstanding balance		7,000						7,000
Senior secured debt, principal outstanding		7,000		$ 2,400			$ 7,000	$ 7,000
Percentage of power purchase agreements							100%	100%
Loan amount				$ 2,400
Alternus Energy Americas [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Part 2 [Line Items]
Principal outstanding balance		$ 3,200						$ 3,200
14 MWp Solar PV Project [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Part 2 [Line Items]
Stated interest rate		24%						24%
Maturity date		May 28, 2024						May 28, 2024
Principal outstanding balance		$ 1,100						$ 1,100
Senior secured debt, principal outstanding		$ 1,100					$ 1,100	$ 1,100
Percentage of power purchase agreements		100%						100%
Loan amount		$ 1,100						$ 1,100
Clean Earth [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Part 2 [Line Items]
Stated interest rate		0%						0%
Principal outstanding balance		$ 1,600						$ 1,600
Promissory note		1,600						1,600
Private Lenders [Member] | AEG MH02 [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Part 2 [Line Items]
Maximum borrowing amount						$ 10,800
Stated interest rate						8%
Maturity date						May 31, 2023
Subsidiaries [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Part 2 [Line Items]
Stated interest rate				5.90%
Principal outstanding balance		$ 3,300						$ 3,300
Initial payment				$ 1,900
Margin rate				2%
Forecast [Member] | ALT US 03, LLC [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Part 2 [Line Items]
Stated interest rate									2.50%

Green Bonds, Convertible and _5

Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Part 3

1 Months Ended

3 Months Ended

12 Months Ended

Jan. 18, 2024 USD ($)

Jan. 18, 2024 EUR (€)

Dec. 21, 2022 USD ($)

Dec. 21, 2022 EUR (€)

Nov. 30, 2021 USD ($)

Jan. 31, 2021 USD ($)

Jan. 31, 2021 EUR (€)

Mar. 31, 2024 USD ($) shares

Mar. 31, 2024 EUR (€)

Dec. 31, 2023 USD ($) $ / shares shares

Dec. 31, 2023 EUR (€)

Dec. 31, 2022 USD ($)

May 08, 2024 shares

May 01, 2024

Apr. 24, 2024 shares

Mar. 31, 2024 EUR (€) shares

Mar. 20, 2024 $ / shares

Feb. 21, 2024 USD ($)

Feb. 21, 2024 EUR (€)

Feb. 20, 2024 shares

Jan. 31, 2024 USD ($)

Jan. 31, 2024 EUR (€)

Jan. 24, 2024 USD ($)

Jan. 24, 2024 EUR (€)

Jan. 23, 2024 shares

Jan. 18, 2024 EUR (€)

Dec. 28, 2023 USD ($)

Dec. 28, 2023 EUR (€)

Oct. 31, 2023

Sep. 30, 2023 USD ($) $ / shares

Sep. 30, 2023 EUR (€)

Mar. 31, 2022 USD ($)

Mar. 31, 2022 EUR (€)

Dec. 31, 2021 USD ($)

Nov. 30, 2021 EUR (€)

Jan. 31, 2021 EUR (€)

Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Part 3 [Line Items]

Shares issued (in Shares) | shares

2,796,554

2,796,554

2,796,554

100,000

81,301

Promissory notes

$ 32,312,000

$ 13,486,000

Closing price (in Dollars per share) | $ / shares

$ 5

Convertible promissory note

$ 1,100,000

Additional paid in capital

$ 500,000

Repayment terms

5 year

5 year

Stated interest rate

10%

10%

0%

Outstanding balance

$ 11,100,000

€ 10,000,000

Interest rate

50%

97%

97%

Effective interest rate

9.50%

9.50%

Debt issuance cost

$ 11,800,000

$ 4,100,000

$ 200,000

Owned subsidiary, description

(i) the minimum Liquidity Covenant that requires the higher of €5.5 million or 5% of the outstanding Nominal Amount, (ii) the minimum Equity Ratio covenant of 25%, and (iii) the Leverage Ratio of NIBD/EBITDA to not be higher than 6.5 times for the year ended December 2021, 6.0 times for the year ended December 31, 2022 and 5.5 times for the period ending on the maturity date of the Bond. The Solis Bond carries a 3 months EURIBOR plus 6.5% per annum interest rate, and has quarterly interest payments, with a bullet payment to be paid on the Maturity Date.

(i) the minimum Liquidity Covenant that requires the higher of €5.5 million or 5% of the outstanding Nominal Amount, (ii) the minimum Equity Ratio covenant of 25%, and (iii) the Leverage Ratio of NIBD/EBITDA to not be higher than 6.5 times for the year ended December 2021, 6.0 times for the year ended December 31, 2022 and 5.5 times for the period ending on the maturity date of the Bond. The Solis Bond carries a 3 months EURIBOR plus 6.5% per annum interest rate, and has quarterly interest payments, with a bullet payment to be paid on the Maturity Date.

Distribution amount (in Euro)

$ 10,000,000

€ 10,000,000

Repayment amount | €

€ 10,000,000

10,000,000

Bondholders amendment fee amount (in Euro) | €

€ 1,400,000

Proceed to transfer ownership

$ 17,500,000

€ 15,800,000

$ 159,000,000

€ 150,000,000

Bond par value (in Dollars per share) | $ / shares

$ 107.5

Solis bond waiver fees

$ 11,100,000

Share capital percentage

100%

100%

Sale of parks

$ 68,500,000

€ 59,100,000,000,000

Waiver fee

$ 11,100,000

Revolving debt financing (in Euro) | €

€ 500,000,000

Project costs (in Euro) | €

€ 420,000,000

Margin rate

0.50%

0.50%

Finance reduces cost rate

33.33%

Commitment fees

$ 1,800,000

€ 1,800,000

Solis Bond [Member]

Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Part 3 [Line Items]

Owned subsidiary, description

(i) the minimum Liquidity Covenant that requires the higher of €5.5 million or 5% of the outstanding Nominal Amount, (ii) the minimum Equity Ratio covenant of 25%, and (iii) the Leverage Ratio of NIBD/EBITDA to not be higher than 6.5 times for the year ended December 2021, 6.0 times for the year ended December 31, 2022 and 5.5 times for the period ending on the maturity date of the Bond, January 6, 2024. The Solis Bond carries a 3 months EURIBOR plus 6.5% per annum interest rate, and has quarterly interest payments, with a bullet payment to be paid on January 6, 2024.

(i) the minimum Liquidity Covenant that requires the higher of €5.5 million or 5% of the outstanding Nominal Amount, (ii) the minimum Equity Ratio covenant of 25%, and (iii) the Leverage Ratio of NIBD/EBITDA to not be higher than 6.5 times for the year ended December 2021, 6.0 times for the year ended December 31, 2022 and 5.5 times for the period ending on the maturity date of the Bond, January 6, 2024. The Solis Bond carries a 3 months EURIBOR plus 6.5% per annum interest rate, and has quarterly interest payments, with a bullet payment to be paid on January 6, 2024.

(i) the minimum Liquidity Covenant that requires the higher of €5.5 million or 5% of the outstanding Nominal Amount, (ii) the minimum Equity Ratio covenant of 25%, and (iii) the Leverage Ratio of NIBD/EBITDA to not be higher than 6.5 times for the year ended December 2021, 6.0 times for the year ended December 31, 2022 and 5.5 times for the period ending on the maturity date of the Bond, January 6, 2024. The Solis Bond carries a 3 months EURIBOR plus 6.5% per annum interest rate, and has quarterly interest payments, with a bullet payment to be paid on January 6, 2024.

Convertible Promissory Note [Member]

Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Part 3 [Line Items]

Promissory notes

$ 1,600,000

Convertible promissory note

$ 938,000

€ 850,000

Stated interest rate

10%

10%

AEG JD 01 LTD [Member]

Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Part 3 [Line Items]

Revolving debt financing (in Euro) | €

€ 80,000,000

Common Stock [Member]

Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Part 3 [Line Items]

Shares issued (in Shares) | shares

225,000

Bondholders [Member]

Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Part 3 [Line Items]

Amendment fee

1%

Proceed to transfer ownership

$ 87,300,000

€ 80,800,000

Subsequent Event [Member]

Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Part 3 [Line Items]

Shares issued (in Shares) | shares

330,000

Subsequent Event [Member] | Minimum [Member]

Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Part 3 [Line Items]

Shares issued (in Shares) | shares

100,000

Subsequent Event [Member] | Common Stock [Member]

Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Part 3 [Line Items]

Closing price (in Dollars per share) | $ / shares

$ 1

Italian Subsidiaries [Member]

Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Part 3 [Line Items]

Proceed to transfer ownership

$ 17,300,000

Polish Subsidiaries [Member]

Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Part 3 [Line Items]

Proceed to transfer ownership

$ 59,100,000

€ 54,400,000

Share capital percentage

100%

100%

Polish Subsidiaries [Member] | Subsequent Event [Member]

Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Part 3 [Line Items]

Proceed to transfer ownership

$ 59,100,000

€ 54,400,000

Share capital percentage

100%

100%

Netherlands Subsidiary [Member]

Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Part 3 [Line Items]

Proceed to transfer ownership

$ 7,000,000

€ 6,500,000

Share capital percentage

100%

100%

Netherlands Subsidiary [Member] | Subsequent Event [Member]

Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Part 3 [Line Items]

Proceed to transfer ownership

$ 7,000,000

€ 6,500,000

Share capital percentage

100%

100%

Other Debt Obligations [Member]

Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Part 3 [Line Items]

Repayment terms

3-year

3-year

Senior secured debt, principal outstanding

$ 242,000,000

€ 200,000,000

Stated interest rate

6.50%

6.50%

Repayment of other debt

$ 40,000,000

€ 33,000,000

Funding acquisitions

87,200,000

72,000,000

Initial funding

$ 125,000,000

€ 110,000,000

Outstanding balance

$ 24,000,000

€ 20,000,000

Percentage of par value

5.50%

5.50%

Other Debt Obligations [Member] | Maximum [Member]

Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Part 3 [Line Items]

Percentage of par value

102%

Other Debt Obligations [Member] | Minimum [Member]

Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Part 3 [Line Items]

Percentage of par value

5.50%

Bond [Member]

Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Part 3 [Line Items]

Outstanding balance

$ 149,500,000

$ 147,200,000

Bond One [Member]

Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Part 3 [Line Items]

Outstanding balance

$ 166,100,000

$ 149,400,000

Solis Bond [Member]

Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Part 3 [Line Items]

Amendment fee percentage

6.50%

Green Bonds, Convertible and _6

Green Bonds, Convertible and Non-convertible Promissory Notes (Details)																	1 Months Ended									3 Months Ended		12 Months Ended
	May 01, 2024 USD ($)	May 01, 2024 EUR (€)	Apr. 19, 2024 USD ($)	Mar. 21, 2024 USD ($) shares	Feb. 14, 2024 USD ($)	Feb. 14, 2024 EUR (€)	Feb. 05, 2024 $ / shares	Jan. 03, 2024 USD ($) shares	Oct. 31, 2023 USD ($)	Aug. 08, 2023 USD ($)	Feb. 28, 2023 USD ($)	Dec. 21, 2022 USD ($)	Dec. 21, 2022 EUR (€)	Jun. 30, 2022 USD ($)	Mar. 31, 2022 USD ($)	Mar. 31, 2022 EUR (€)	Jan. 31, 2024 USD ($) shares	Jan. 24, 2024 USD ($)	Dec. 31, 2023 USD ($) $ / shares shares	Jul. 31, 2023 USD ($)	May 31, 2022 USD ($)	Nov. 30, 2021 USD ($)	Nov. 30, 2021 EUR (€)	Jan. 31, 2021 USD ($)	Jan. 31, 2021 EUR (€)	Mar. 31, 2024 USD ($) $ / shares shares	Mar. 31, 2024 EUR (€)	Dec. 31, 2023 USD ($) $ / shares shares	Dec. 31, 2023 EUR (€)	Dec. 31, 2022 USD ($) shares	May 08, 2024 shares	Mar. 31, 2024 EUR (€) shares	Mar. 20, 2024 $ / shares	Feb. 21, 2024 USD ($)	Feb. 21, 2024 EUR (€)	Feb. 20, 2024 shares	Jan. 31, 2024 EUR (€)	Jan. 24, 2024 EUR (€)	Jan. 23, 2024 shares	Jan. 18, 2024 USD ($)	Jan. 18, 2024 EUR (€)	Dec. 28, 2023 USD ($)	Dec. 28, 2023 EUR (€)	Sep. 30, 2023 USD ($)	Sep. 30, 2023 EUR (€)	May 31, 2023	Mar. 31, 2022 EUR (€)	Dec. 31, 2021 USD ($)	Nov. 30, 2021 EUR (€)	Jan. 31, 2021 EUR (€)
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) [Line Items]
Debt issuance cost																			$ 4,100,000			$ 11,800,000						$ 4,100,000		$ 200,000
Amortization of debt discounts																										$ 700,000		$ 4,900,000		$ 3,900,000
Stated interest rate									0%																	10%						10%
Loan amount																																												$ 3,600,000
Margin rate												0.50%	0.50%
Exercisable price per share (in Dollars per share) | $ / shares																			$ 0.01									$ 0.01
Warrants term																			5 years									5 years
Shares issued (in Shares) | shares																			2,796,554							2,796,554		2,796,554				2,796,554				100,000			81,301
Repayment amount | €																											€ 10,000,000		€ 10,000,000
Closing price (in Dollars per share) | $ / shares																			$ 5									$ 5
Additional paid in capital																			$ 500,000									$ 500,000
Convertible promissory note																			$ 1,100,000									$ 1,100,000
Repayment terms																												5 year	5 year
Effective interest rate																						9.50%																											9.50%
Outstanding balance															$ 11,100,000																																€ 10,000,000
Owned subsidiary, description																										(i) the minimum Liquidity Covenant that requires the higher of €5.5 million or 5% of the outstanding Nominal Amount, (ii) the minimum Equity Ratio covenant of 25%, and (iii) the Leverage Ratio of NIBD/EBITDA to not be higher than 6.5 times for the year ended December 2021, 6.0 times for the year ended December 31, 2022 and 5.5 times for the period ending on the maturity date of the Bond. The Solis Bond carries a 3 months EURIBOR plus 6.5% per annum interest rate, and has quarterly interest payments, with a bullet payment to be paid on the Maturity Date.	(i) the minimum Liquidity Covenant that requires the higher of €5.5 million or 5% of the outstanding Nominal Amount, (ii) the minimum Equity Ratio covenant of 25%, and (iii) the Leverage Ratio of NIBD/EBITDA to not be higher than 6.5 times for the year ended December 2021, 6.0 times for the year ended December 31, 2022 and 5.5 times for the period ending on the maturity date of the Bond. The Solis Bond carries a 3 months EURIBOR plus 6.5% per annum interest rate, and has quarterly interest payments, with a bullet payment to be paid on the Maturity Date.
Distribution amount (in Euro)																										$ 10,000,000			€ 10,000,000
Proceed to transfer ownership																																										$ 17,500,000	€ 15,800,000	$ 159,000,000	€ 150,000,000
Share capital percentage																																										100%	100%
Proceeds from Stock Options Exercised					$ 68,500,000	€ 59,100,000
Interest rate	50%	50%													97%																																97%
Revolving debt financing (in Euro) | €													€ 500,000,000
Finance reduces cost rate													33.33%
Commitment fees												$ 1,800,000	€ 1,800,000
Warrant [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) [Line Items]
Warrants to purchase (in Shares) | shares																			12,345,000							12,435,000		12,345,000		11,945,000		12,435,000
Warrants term																			5 years									5 years
Promissory Note [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) [Line Items]
Debt issuance cost																										$ 900,000
Stated interest rate											2.50%			2.50%					0%									0%
Maturity date											May 31, 2024			Jun. 29, 2023
Senior secured debt, principal outstanding																			$ 4,300,000							$ 5,400,000		$ 4,300,000
Loan amount											$ 920,000			$ 5,900,000
Exercisable price per share (in Dollars per share) | $ / shares																			$ 0.01							$ 0.01		$ 0.01
Repayment amount																												$ 1,600,000
Additional paid in capital																			$ 500,000									500,000
Principal issued										$ 650,000
Senior Secured Debt [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) [Line Items]
Stated interest rate											16%																																			18%
Recognized interest																										$ 900,000
Solis Bond [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) [Line Items]
Senior secured debt, principal outstanding																			11,000,000							10,800,000		11,000,000
Distribution amount (in Euro) | €																											€ 10,000,000
32 MWp Solar PV Project [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) [Line Items]
Stated interest rate																				24%
Maturity date																				Feb. 29, 2024
Senior secured debt, principal outstanding																			7,000,000	$ 2,400,000						$ 7,000,000		$ 7,000,000
Loan amount																				$ 2,400,000
Percentage of power purchase agreements																										100%	100%	100%	100%
Working Capital Loan [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) [Line Items]
Stated interest rate									0%																	10%						10%
Maturity date									Mar. 31, 2024
Senior secured debt, principal outstanding																			$ 3,200,000							$ 1,800,000		$ 3,200,000
Loan amount									$ 3,200,000
Increased principal amount																										$ 3,600,000
Working Capital Loan [Member] | Warrant [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) [Line Items]
Warrants to purchase (in Shares) | shares																										90,000						90,000
Exercisable price per share (in Dollars per share) | $ / shares																										$ 0.01
Warrants term																										5 years						5 years
Fair value of warrants																										$ 86,000
14 MWp Solar PV Project [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) [Line Items]
Stated interest rate																			24%									24%
Maturity date																			May 28, 2024									May 28, 2024	May 28, 2024
Senior secured debt, principal outstanding																			$ 1,100,000							1,100,000		$ 1,100,000
Loan amount																			$ 1,100,000									$ 1,100,000
Percentage of power purchase agreements																			100%									100%	100%
Convertible Promissory Note [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) [Line Items]
Stated interest rate																	10%																				10%
Convertible promissory note																	$ 938,000																				€ 850,000
Conversion of debt								$ 1,000,000									$ 1,000,000
Other Secured Debt [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) [Line Items]
Debt issuance cost																										$ 11,800,000
Stated interest rate															97%									6.50%																							97%			6.50%
Loan amount																								$ 242,000,000																										€ 200,000,000
Repayment of other debt																								40,000,000	€ 33,000,000
Funding acquisitions																								87,200,000	72,000,000
Principal issued															$ 11,100,000	€ 10,000,000						$ 24,000,000	€ 20,000,000	$ 125,000,000	€ 110,000,000
Percentage of par value																										102%	102%
Effective interest rate															9.50%																																9.50%
Private Lenders [Member] | Senior Secured Debt [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) [Line Items]
Maximum borrowing amount																					$ 10,800,000
Stated interest rate																					8%
Maturity date																					May 31, 2023
Restricted Common Stock [Member] | Convertible Promissory Note [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) [Line Items]
Debt converted into shares (in Shares) | shares								1,320,000									1,320,000
Common Stock [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) [Line Items]
Shares issued (in Shares) | shares																			225,000									225,000
Sponsor [Member] | Promissory Note [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) [Line Items]
Senior secured debt, principal outstanding																			$ 1,600,000							$ 1,400,000		$ 1,600,000
Sponsor [Member] | Solis Bond [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) [Line Items]
Stated interest rate				25%
Shares issued (in Shares) | shares				225,000
Repayment amount				$ 1,200,000
Closing price (in Dollars per share) | $ / shares																										$ 0.47
Bondholders [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) [Line Items]
Proceed to transfer ownership																										$ 87,300,000						€ 80,800,000
Subsequent Event [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) [Line Items]
Exercisable price per share (in Dollars per share) | $ / shares							$ 0.01
Shares issued (in Shares) | shares																															330,000
Principal issued			$ 50,000
Proceeds from Stock Options Exercised					$ 68,500,000	€ 59,100,000,000,000
Subsequent Event [Member] | Promissory Note [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) [Line Items]
Maturity date							Feb. 28, 2025
Subsequent Event [Member] | Solis Bond [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) [Line Items]
Interest payment	$ 1,069,985	€ 1,000,000
Subsequent Event [Member] | Common Stock [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) [Line Items]
Closing price (in Dollars per share) | $ / shares																																	$ 1
Other Debt Obligations [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) [Line Items]
Stated interest rate																								6.50%																										6.50%
Senior secured debt, principal outstanding																								$ 242,000,000																										€ 200,000,000
Repayment terms																								3-year	3-year
Repayment of other debt																								$ 40,000,000	€ 33,000,000
Funding acquisitions																								$ 87,200,000	€ 72,000,000
Percentage of par value																										5.50%	5.50%
Outstanding balance																						$ 24,000,000																											€ 20,000,000
Bond [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) [Line Items]
Outstanding balance																														$ 149,500,000																		$ 147,200,000
Bond [Member] | Other Secured Debt [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) [Line Items]
Outstanding balance																			166,100,000							$ 87,300,000		166,100,000
Alternus Energy Americas [Member] | Promissory Note [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) [Line Items]
Senior secured debt, principal outstanding																			717,000							717,000		717,000
Alt Spain Holdco [Member] | 32 MWp Solar PV Project [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) [Line Items]
Stated interest rate																				5.90%
Maturity date																		Jul. 28, 2024
Senior secured debt, principal outstanding																			3,200,000							$ 3,200,000		3,200,000
Initial payment																				$ 1,900,000
Margin rate																				2%
Polish Subsidiaries [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) [Line Items]
Proceed to transfer ownership																																								$ 59,100,000	€ 54,400,000
Share capital percentage																																								100%	100%
Polish Subsidiaries [Member] | Subsequent Event [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) [Line Items]
Proceed to transfer ownership																		$ 59,100,000																				€ 54,400,000
Share capital percentage																		100%																				100%
Netherlands Subsidiary [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) [Line Items]
Proceed to transfer ownership																																		$ 7,000,000	€ 6,500,000
Share capital percentage																																		100%	100%
Netherlands Subsidiary [Member] | Subsequent Event [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) [Line Items]
Proceed to transfer ownership																																		$ 7,000,000	€ 6,500,000
Share capital percentage																																		100%	100%
Sponsor [Member]
Green Bonds, Convertible and Non-convertible Promissory Notes (Details) [Line Items]
Promissory note																			$ 1,100,000									$ 1,100,000

Green Bonds, Convertible and _7

Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Schedule of Debt Balances - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Mar. 31, 2024
Schedule of Debt Balances [Abstract]
Senior Secured Green Bonds	$ 166,122	$ 149,481
Senior Secured debt and promissory notes secured	32,312	13,486
Total debt	198,434	162,967	$ 118,787
Less current maturities	(198,434)		$ (118,787)
Long term debt, net of current maturities		162,967
Current Maturities	198,434
Less current debt discount	(892)
Current Maturities net of debt discount	197,542
Long-term maturities		162,967
Less long-term debt discount		(4,272)
Long-term maturities net of debt discount		$ 158,695

Leases (Details)

Leases (Details) - USD ($) $ in Thousands	1 Months Ended
	Oct. 31, 2023	Apr. 30, 2022	Mar. 31, 2022	Mar. 31, 2024	Dec. 31, 2023
Leases [Line Items]
Lease cost (in Dollars)	$ 32	$ 147
Rakowic Park [Member]
Leases [Line Items]
Lease cost (in Dollars)			$ 69
Komorowo Park [Member]
Leases [Line Items]
Lease cost (in Dollars)			$ 7
Minimum [Member]
Leases [Line Items]
Lease term					4 years
Remaining lease terms				4 years
Maximum [Member]
Leases [Line Items]
Lease term					28 years
Remaining lease terms				28 years
US [Member]
Leases [Line Items]
Lease term		7 years 6 months
Spain [Member]
Leases [Line Items]
Lease term	35 years

Leases (Details) - Schedule of

Leases (Details) - Schedule of Key Components of the Company's Operating Leases - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Schedule of Key Components of the Company's Operating Leases [Abstract]
Operating Lease - Operating Cash Flows (Fixed Payments)	$ 75	$ 189	$ 99
Operating Lease - Operating Cash Flows (Liability Reduction)	61	129	54
New ROU Assets - Operating Leases		$ 409	$ 8,482
Weighted Average Lease Term - Operating Leases (years)	12 years 11 months 26 days	13 years 2 months 26 days	7 years 18 days
Weighted Average Discount Rate - Operating Leases	7.65%	7.65%	7.10%

Leases (Details) - Schedule o_2

Leases (Details) - Schedule of Maturities of Lease Liabilities - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Schedule of Maturities of Lease Liabilities [Abstract]
2024	$ 235	$ 231
2025	241	237
2026	247	242
2027	215	248
2028	2,021	216
Thereafter		2,064
Total lease payments	3,113	3,238
Less imputed interest	(1,748)	(1,811)
Total	$ 1,365	$ 1,427

Commitments and Contingencies (

Commitments and Contingencies (Details)	May 04, 2023 USD ($)	May 04, 2023 PLN (zł)	Jun. 30, 2024 USD ($)	Oct. 31, 2023 USD ($)
Commitments and Contingencies [Line Items]
Litigation claim settlement	$ 5,800,000	zł 24,980,589
Loss contingency	$ 6,800,000
Hover Energy, LLC [Member]
Commitments and Contingencies [Line Items]
Prepaid development fees				$ 500,000
Forecast [Member] | Hover Energy, LLC [Member]
Commitments and Contingencies [Line Items]
Prepaid development fees			$ 500,000

Asset Retirement Obligations (D

Asset Retirement Obligations (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Asset Retirement Obligations [Line Items]
Discount rate percentage		7.50%	7.10%
Discount rate percentage	7.70%	7.70%

Asset Retirement Obligations _2

Asset Retirement Obligations (Details) - Schedule of Asset Retirement Obligations - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Schedule of Asset Retirement Obligations [Abstract]
ARO Liability - Balance	$ 197	$ 397	$ 411
Additional obligations incurred
Disposals		(235)
Accretion expense	3	24	20
Foreign exchange gain/(loss)		11	(34)
ARO Liability - Balance	$ 196	$ 197	$ 397

Development Cost (Details)

Development Cost (Details) zł in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)	Dec. 31, 2023 PLN (zł)	Dec. 31, 2022 USD ($)
Development Cost [Line Items]
Development expenses due	$ 9.6
Development expenses paid	4.2
Accrued liabilities	5.4
Renewable energy projects [Member]
Development Cost [Line Items]
Development cost			$ 11.4
Project 1 [Member]
Development Cost [Line Items]
Development cost	$ 9.6	zł 45

Development Cost (Details) - Sc

Development Cost (Details) - Schedule of Development Cost - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Schedule of Development Cost [Abstract]
Project 1				$ 10,162
Miscellaneous development cost				1,210
Total	$ 7	$ 111	$ 798	$ 11,372

Discontinued Operations Sold (D

Discontinued Operations Sold (Details) - USD ($) $ in Millions	1 Months Ended
	Feb. 21, 2024	Jan. 19, 2024	Dec. 31, 2023
Discontinued Operations Sold [Abstract]
Assets in disposal group			$ 11.8
Cash consideration	$ 7.1	$ 59.4
Recognized gain	1.3	3.5
Cost amont	$ 0.5	$ 0.8

Discontinued Operations Sold _2

Discontinued Operations Sold (Details) - Schedule of Balances and Results of the Polish and Netherlands Disposal Groups - USD ($) $ in Thousands	Feb. 21, 2024	Jan. 19, 2024	Dec. 31, 2023	Dec. 31, 2022
Poland [Member]
Assets:
Cash & cash equivalents		$ 630	$ 630	$ 431
Other current assets		442	443	1,105
Property, plant, and equipment, net		63,107	63,107	69,656
Operating leases, non-current - assets		5,923	5,923	5,378
Total assets held for sale		70,102	70,103	76,570
Liabilities:
Accounts payable		2,933	2,935	1,760
Operating leases, current – liabilities		281	281	233
Other current liabilities		25	1,549	1,157
Operating leases, non-current - liabilities		5,798	5,798	4,995
Other non-current liabilities		985	985	824
Total liabilities to be disposed of		10,022	11,548	8,969
Net assets held for sale		$ 60,080	58,555	67,601
Netherlands [Member]
Assets:
Cash & cash equivalents	$ 75		155	13
Accounts receivable, net			99	487
Other current assets	178		58	82
Property, plant, and equipment, net	7,669		7,845	7,984
Operating leases, non-current - assets	1,441		1,469	1,438
Other non-current assets	1,192		1,214	1,176
Total assets held for sale	10,555		10,840	11,180
Liabilities:
Accounts payable	945		925	23
Operating leases, current – liabilities	55		55	52
Other current liabilities	95		430	235
Operating leases, non-current - liabilities	1,273		1,301	1,312
Total liabilities to be disposed of	2,368		2,711	1,622
Net assets held for sale	$ 8,187		$ 8,129	$ 9,558

Discontinued Operations Sold _3

Discontinued Operations Sold (Details) - Schedule of Recognized in Discontinued Operations in the Statement of Profit or Loss - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Poland [Member]
Discontinued Operations in the Statement of Profit or Loss [Line Items]
Revenues	$ 106	$ 1,105	$ 7,593	$ 10,709
Operating Expenses
Cost of revenues	(101)	(936)	(3,768)	(4,104)
Depreciation, amortization, and accretion	(123)	(609)	(2,563)	(2,482)
Loss on disposal of asset			(130)
Total operating expenses	3,260	(1,545)	(6,461)	(6,586)
Income from discontinued operations	3,366	(440)	1,132	4,123
Other income/(expense):
Impairment loss recognized on the remeasurement to fair value less costs to sell	(688)	(1,224)	(11,766)
Interest expense	(688)	(1,224)	(5,650)	(3,893)
Other expense			(157)	(30)
Total other expenses	2,678	(1,664)	(17,573)	(3,923)
Income/(Loss) before provision for income taxes	2,678	(1,664)	(16,441)	200
Income taxes				(21)
Net income/(loss) from discontinued operations			(16,441)	179
Impact of discontinued operations on EPS
Net income/(loss) attributable to common stockholders, basic	2,678	(1,664)	(16,441)	179
Net income/(loss) attributable to common stockholders, diluted	$ 2,678	$ (1,664)	$ (16,441)	$ 179
Net income/(loss) per share attributable to common stockholders, basic (in Dollars per share)	$ 0.04	$ (0.03)	$ (0.28)	$ 0
Net income/(loss) per share attributable to common stockholders, diluted (in Dollars per share)	$ 0.04	$ (0.03)	$ 0	$ 0
Weighted-average common stock outstanding, basic (in Shares)	65,077,094	57,500,000	57,862,598	57,500,000
Weighted-average common stock outstanding, diluted (in Shares)			57,862,598	57,500,000
Netherlands [Member]
Discontinued Operations in the Statement of Profit or Loss [Line Items]
Revenues	$ 16	$ 202	$ 2,840	$ 1,596
Operating Expenses
Cost of revenues	(115)	(61)	(450)	(368)
Depreciation, amortization, and accretion	(57)	(126)	(400)	(500)
Loss on disposal of asset			(7)
Total operating expenses	(1,506)	(187)	(857)	(868)
Income from discontinued operations	(1,490)	15	1,983	728
Other income/(expense):
Impairment loss recognized on the remeasurement to fair value less costs to sell	(113)	(248)
Interest expense	(113)	(248)	(1,131)	(787)
Other expense			(62)
Total other expenses	(1,603)	(233)	(1,193)	(787)
Income/(Loss) before provision for income taxes	(1,603)	(233)	790	(59)
Income taxes			(161)
Net income/(loss) from discontinued operations			629	(59)
Impact of discontinued operations on EPS
Net income/(loss) attributable to common stockholders, basic	(1,603)	(233)	629	(59)
Net income/(loss) attributable to common stockholders, diluted	$ (1,603)	$ (233)	$ 629	$ (59)
Net income/(loss) per share attributable to common stockholders, basic (in Dollars per share)	$ (0.02)	$ 0	$ 0.01	$ 0
Net income/(loss) per share attributable to common stockholders, diluted (in Dollars per share)	$ (0.02)	$ 0	$ 0.01	$ 0
Weighted-average common stock outstanding, basic (in Shares)	65,077,094	57,500,000	57,862,598	57,500,000
Weighted-average common stock outstanding, diluted (in Shares)			57,862,598	57,500,000

Italy Sale Disclosure (Details)

Italy Sale Disclosure (Details) $ in Millions	Dec. 28, 2023 USD ($)
Italy Sale Disclosure [Line Items]
Cash consideration	$ 17.5
Disposal group loss	5.5
Sale cost	$ 0.6

Italy Sale Disclosure (Detail_2

Italy Sale Disclosure (Details) - Schedule of Remaining Balances and Results of the Italian Assets - Italy [Member] - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 28, 2023
Italy Sale Disclosure (Details) - Schedule of Remaining Balances and Results of the Italian Assets [Line Items]
Cash & cash equivalents	$ 87,000		$ 100,000	$ 295,000	$ 100,000
Accounts receivable, net	330,000		338,000	932,000
Other current assets	3,966,000		3,819,000	1,030,000	338,000
Property, plant, and equipment, net	4,383,000		4,257,000	21,735,000
Operating leases, non-current - assets				4,000
Other non-current assets				800,000	3,819,000
Total assets held for sale				24,796,000	4,257,000
Accounts payable	17,000		21,000	109,000	21,000
Other current liabilities	3,797,000		3,658,000	1,080,000	578,000
Other non-current liabilities		$ 655,000		216,000
Total liabilities	586,000		599,000	1,405,000	599,000
Net assets held for sale				23,391,000	$ 3,658,000
Revenues			3,360,000	3,354,000
Operating Expenses
Cost of revenues		(262,000)	(1,204,000)	(812,000)
Selling, general, and administrative	(8,000)	(42,000)	(69,000)	(77,000)
Depreciation, amortization, and accretion		(410,000)	(1,638,000)	(1,614,000)
Loss on disposal of asset	(8,000)	(59,000)	(5,501,000)
Total operating expenses	8,000	714,000	(8,412,000)	(2,503,000)
Income/(Loss) from discontinued operations		(36,000)	(5,052,000)	851,000
Other income/(expense):
Other expense	(8,000)	(95,000)	(15,000)
Other income				22,000
Total other expenses		(36,000)	(15,000)	22,000
Income/(Loss) before provision for income taxes	(8,000)	(95,000)	(5,067,000)	873,000
Income taxes
Net income/(loss) from discontinued operations	$ (8,000)	$ (95,000)	$ (5,067,000)	$ 873,000
Impact on EPS
Net income/(loss) attributable to common stockholders, basic (in Dollars per share)	$ 0	$ 0	$ (5,067)	$ 873
Net income/(loss) attributable to common stockholders, diluted (in Dollars per share)	$ 0	$ 0	$ (5,067)	$ 873
Net income/(loss) per share attributable to common stockholders, basic	$ 65,077,094,000	$ 57,500,000,000	$ (90)	$ 20
Net income/(loss) per share attributable to common stockholders, diluted	$ 65,077,094,000	$ 57,500,000,000	$ (90)	$ 20
Weighted-average common stock outstanding, basic (in Shares)			57,862,598	57,500,000
Weighted-average common stock outstanding, diluted (in Shares)			57,862,598	57,500,000

Shareholders' Equity (Details)

Shareholders' Equity (Details) - $ / shares	Mar. 31, 2024	Feb. 20, 2024	Jan. 23, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 22, 2008
Shareholders’ Equity [Line Items]
Common shares, shares authorized	150,000,000			150,000,000	150,000,000
Common shares, shares issued	81,396,664			71,905,363	57,500,000
Common shares, shares outstanding	81,396,664			71,905,363	57,500,000	71,905,363
Preferred stock, shares authorized	1,000,000			1,000,000	1,000,000
Preferred stock, shares issued	0			0	0
Preferred stock, shares outstanding	0			0	0
Shares issued	2,796,554	100,000	81,301	2,796,554
Market value price per share (in Dollars per share)	$ 10	$ 0.35	$ 1.01	$ 10
Warrants issued				90,000
Warrants term				5 years
Warrant [Member]
Shareholders’ Equity [Line Items]
Warrants to purchase	12,435,000			12,345,000	11,945,000
Issued additional warrants				400,000
Warrants term				5 years
Class A Common Stock [Member]
Shareholders’ Equity [Line Items]
Common shares, shares authorized					100,000,000
Class B Common Stock [Member]
Shareholders’ Equity [Line Items]
Common shares, shares authorized					10,000,000

Shareholders' Equity (Details)

Shareholders' Equity (Details) - Schedule of Common Stock were Issued and Outstanding - Warrant [Member] - $ / shares			3 Months Ended		12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Shareholders' Equity (Details) - Schedule of Common Stock were Issued and Outstanding [Line Items]
Warrants, Outstanding Balance	12,345,000	11,945,000	12,435,000	11,945,000	12,345,000	11,945,000
Weighted Average Exercise Price, Outstanding Balance	$ 11.22	$ 11.5	$ 11.14	$ 11.5	$ 11.22	$ 11.5
Weighted Average Remaining Contractual Term (Years), Outstanding Balance	4 years 11 months 4 days	5 years 11 months 23 days	4 years 8 months 23 days	5 years 11 months 23 days	4 years 11 months 4 days	5 years 11 months 23 days
Warrants, Exercisable	12,345,000		12,435,000	11,945,000	12,345,000
Weighted Average Exercise Price, Exercisable	$ 11.22		$ 11.14	$ 11.5	$ 11.22
Weighted Average Remaining Contractual Term (Years), Exercisable			4 years 8 months 23 days	5 years 11 months 23 days	4 years 11 months 4 days
Warrants, Issued			90,000		400,000
Weighted Average Exercise Price, Issued			$ 0.01		$ 0.35
Weighted Average Remaining Contractual Term (Years), Issued			10 days		1 month 28 days
Warrants, Expired
Weighted Average Exercise Price, Expired
Weighted Average Remaining Contractual Term (Years), Expired

Segment and Geographic Inform_3

Segment and Geographic Information (Details) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Segment and Geographic Information [Line Items]
Revenue (in Dollars)	$ 2,180	$ 3,846	$ 20,084	$ 17,089
Number of reportable segments	2
Customer Concentration Risk [Member] | One Customer [Member] | Revenue Benchmark [Member]
Segment and Geographic Information [Line Items]
Operational revenues percentage			35%	29%
Customer Concentration Risk [Member] | One Customer [Member] | Accounts Receivable [Member]
Segment and Geographic Information [Line Items]
Operational revenues percentage			23%
Continuing Operations [Member] | One Customer [Member]
Segment and Geographic Information [Line Items]
Revenue (in Dollars)			$ 11,400	$ 9,700
Continuing Operations [Member] | Customer Concentration Risk [Member] | Three Customers [Member] | Accounts Receivable [Member]
Segment and Geographic Information [Line Items]
Operational revenues percentage			61%
Discontinued Operations [Member] | Two Customers [Member]
Segment and Geographic Information [Line Items]
Revenue (in Dollars)			$ 11,200	$ 14,200
Discontinued Operations [Member] | Customer Concentration Risk [Member] | One Customer [Member] | Accounts Receivable [Member]
Segment and Geographic Information [Line Items]
Operational revenues percentage			23%
Discontinued Operations [Member] | Customer Concentration Risk [Member] | Two Customers [Member] | Revenue Benchmark [Member]
Segment and Geographic Information [Line Items]
Operational revenues percentage			34%	42%

Segment and Geographic Inform_4

Segment and Geographic Information (Details) - Schedule of Geographic information related to the Company’s reportable segments - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Schedule of Geographic Information Related to the Company’s Single Reportable Segment [Line Items]
Revenue by Segment	$ 2,180	$ 3,846	$ 20,084	$ 17,089
Operating Loss by Segment	(7,583)	(5,252)	(69,464)	(18,448)
Europe
Assets by Segment	84,354		185,286	178,315
Europe
Liabilities by Segment	156,073		248,540	180,897
Europe
Geographic Information by Segment			30,517	29,394
Europe
Depreciation, amortization, and accretion	568	842	3,657	3,677
Interest expense	4,984	3,468	18,562	10,256
Income taxes	526	777	2,488	2,015
Net Loss	(7,583)	(5,252)	(69,464)	(18,448)
Europe [Member]
Schedule of Geographic Information Related to the Company’s Single Reportable Segment [Line Items]
Operating Loss by Segment	(2,907)	(4,310)	(46,301)	(14,977)
Europe
EBITDA by Segment	2,258	2,122	6,874	6,537
Europe
Depreciation, amortization, and accretion	(699)	(1,574)	(6,563)	(6,617)
Interest expense	(4,466)	(4,858)	(23,453)	(14,876)
Income taxes			(161)	(21)
Solis Bond Waiver			(11,766)
Impairment loss recognized on the remeasurement to fair value less costs to sell			(11,232)
Net Loss	(2,907)	(4,310)	(46,301)	(14,977)
US [Member]
Schedule of Geographic Information Related to the Company’s Single Reportable Segment [Line Items]
Revenue by Segment			116	25
Operating Loss by Segment	(4,676)	(942)	(23,163)	(3,471)
Europe
EBITDA by Segment	(2,827)	(857)	(4,560)	(3,370)
Europe
Depreciation, amortization, and accretion	(49)	(2)	(57)	(42)
Interest expense	(1,317)	(83)	(1,889)	(59)
Income taxes			(15)
Net Loss	(4,676)	(942)	(23,163)	(3,471)
US
Valuation on FPA Asset			(16,642)
Revenue by Segment [Member]
Schedule of Geographic Information Related to the Company’s Single Reportable Segment [Line Items]
Revenue by Segment			20,084	17,089
Revenue by Segment [Member] | Europe [Member]
Schedule of Geographic Information Related to the Company’s Single Reportable Segment [Line Items]
Revenue by Segment			30,401	29,368
Revenue by Segment [Member] | US [Member]
Schedule of Geographic Information Related to the Company’s Single Reportable Segment [Line Items]
Revenue by Segment			116	26
Revenue by Segment [Member] | Discontinued Operations [Member] | Europe [Member]
Schedule of Geographic Information Related to the Company’s Single Reportable Segment [Line Items]
Revenue by Segment			(10,433)	(12,305)
Operating Loss [Member]
Schedule of Geographic Information Related to the Company’s Single Reportable Segment [Line Items]
Operating Loss by Segment	(7,583)	(5,252)	(69,464)	(18,448)
Europe
Net Loss	(7,583)	(5,252)	(69,464)	(18,448)
Operating Loss [Member] | Europe [Member]
Schedule of Geographic Information Related to the Company’s Single Reportable Segment [Line Items]
Operating Loss by Segment	(2,908)	(4,310)	(46,301)	(14,978)
Europe
Net Loss	(2,908)	(4,310)	(46,301)	(14,978)
Operating Loss [Member] | US [Member]
Schedule of Geographic Information Related to the Company’s Single Reportable Segment [Line Items]
Operating Loss by Segment	(4,675)	(942)	(23,163)	(3,470)
Europe
Net Loss	(4,675)	(942)	(23,163)	(3,470)
Assets by Segment [Member] | Europe [Member]
Europe
Assets by Segment	62,944		162,328	173,080
Assets by Segment [Member] | Europe [Member] | Fixed Assets [Member]
Europe
Assets by Segment	42,209		125,600	141,862
Assets by Segment [Member] | Europe [Member] | Other Assets [Member]
Europe
Assets by Segment	20,735		36,728	31,218
Assets by Segment [Member] | US [Member]
Europe
Assets by Segment	21,410		22,958	5,235
Assets by Segment [Member] | US [Member] | Fixed Assets [Member]
Europe
Assets by Segment	6,556		5,119	599
Assets by Segment [Member] | US [Member] | Other Assets [Member]
Europe
Assets by Segment	14,854		17,839	4,636
Liabilities by Segment [Member] | Europe [Member]
Europe
Liabilities by Segment	127,794		219,672	175,117
Liabilities by Segment [Member] | Europe [Member] | Debt [Member]
Europe
Liabilities by Segment	99,686		180,294	155,896
Liabilities by Segment [Member] | Europe [Member] | Other Liabilities [Member]
Europe
Liabilities by Segment	28,108		39,378	19,221
Liabilities by Segment [Member] | US [Member]
Europe
Liabilities by Segment	28,279		28,868	5,780
Liabilities by Segment [Member] | US [Member] | Debt [Member]
Europe
Liabilities by Segment	16,582		17,247	2,793
Liabilities by Segment [Member] | US [Member] | Other Liabilities [Member]
Europe
Liabilities by Segment	11,697		11,621	2,987
Geographic Information by Segment [Member]
Europe
Geographic Information by Segment			30,517	29,394
Geographic Information by Segment [Member] | Revenue – Discontinued Operations [Member]
Europe
Geographic Information by Segment			(10,433)	(12,305)
Geographic Information by Segment [Member] | Long-lived Assets [Member]
Europe
Geographic Information by Segment			185,286	178,315
Geographic Information by Segment [Member] | Europe [Member] | Long-lived Assets [Member]
Europe
Geographic Information by Segment			162,328	173,080
Geographic Information by Segment [Member] | Europe [Member] | Revenue [Member]
Europe
Geographic Information by Segment			30,401	29,368
Geographic Information by Segment [Member] | Europe [Member] | Revenue – Discontinued Operations [Member]
Europe
Geographic Information by Segment			(10,433)	(12,305)
Geographic Information by Segment [Member] | US [Member] | Revenue [Member]
Europe
Geographic Information by Segment			116	26
Geographic Information by Segment [Member] | US [Member] | Revenue [Member] | Long-lived Assets [Member]
Europe
Geographic Information by Segment			22,958	5,235
EBITDA [Member]
Europe
EBITDA by Segment	$ (569)	$ 1,265	2,314	3,167
Country Renewable Programs [Member] | Europe [Member]
Schedule of Geographic Information Related to the Company’s Single Reportable Segment [Line Items]
Revenue by Segment			8,356	9,854
Country Renewable Programs [Member] | Revenue by Product Type [Member]
Schedule of Geographic Information Related to the Company’s Single Reportable Segment [Line Items]
Revenue by Segment			8,356	9,854
Country Renewable Programs [Member] | Revenue by Product Type [Member] | US [Member]
Schedule of Geographic Information Related to the Company’s Single Reportable Segment [Line Items]
Revenue by Segment
Green Certificates [Member] | Revenue by Product Type [Member]
Schedule of Geographic Information Related to the Company’s Single Reportable Segment [Line Items]
Revenue by Segment			10,677	9,452
Green Certificates [Member] | Revenue by Product Type [Member] | Europe [Member]
Schedule of Geographic Information Related to the Company’s Single Reportable Segment [Line Items]
Revenue by Segment			10,677	9,452
Green Certificates [Member] | Revenue by Product Type [Member] | US [Member]
Schedule of Geographic Information Related to the Company’s Single Reportable Segment [Line Items]
Revenue by Segment
Energy Offtake Agreements [Member] | Revenue by Product Type [Member]
Schedule of Geographic Information Related to the Company’s Single Reportable Segment [Line Items]
Revenue by Segment			11,484	10,088
Energy Offtake Agreements [Member] | Revenue by Product Type [Member] | Europe [Member]
Schedule of Geographic Information Related to the Company’s Single Reportable Segment [Line Items]
Revenue by Segment			11,368	10,062
Energy Offtake Agreements [Member] | Revenue by Product Type [Member] | US [Member]
Schedule of Geographic Information Related to the Company’s Single Reportable Segment [Line Items]
Revenue by Segment			$ 116	$ 26

Income Tax Provision (Details)

Income Tax Provision (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Income Tax Provision [Line Items]
Valuation allowance increased		$ 2,500
Foreign net operating loss carryovers		3,900
Net operating loss carryover subject to expire		42
Effective tax rate, percentage	0%
Valuation Allowance [Member]
Income Tax Provision [Line Items]
Effective tax rate, percentage	0%
Ireland [Member]
Income Tax Provision [Line Items]
Foreign net operating loss carryovers		2,400
Luxembourg [Member]
Income Tax Provision [Line Items]
Foreign net operating loss carryovers		$ 51

Income Tax Provision (Details)

Income Tax Provision (Details) - Schedule of Relationship Between Tax expense and Accounting Profit - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Schedule of Relationship Between Tax expense and Accounting Profit [Abstract]
Income before taxes			$ (53,637)	$ (18,569)
Tax at the applicable rate of 21%			(11,263)	(3,899)
State income taxes, net of federal benefit
Permanent items			5,852	1,439
Tax effect of differences in foreign tax rates			2,622	2,046
Other			302	(140)
Change in valuation allowance			2,502	554
Actual income tax expense (benefit)			$ 15

Income Tax Provision (Details_2

Income Tax Provision (Details) - Schedule of Significant Portions of the Net Deferred Tax Assets - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Schedule of Significant Portions of the Net Deferred Tax Assets [Abstract]
Net operating losses	$ 1,329	$ 1,249
Interest expense carryforward	4,343	1,948
Lease liabilities	312	207
Total deferred tax assets	5,984	3,404
Deferred tax asset valuation allowance	(5,693)	(3,203)
Net deferred tax assets	291	201
Depreciation		(1)
Right-of-use asset	(291)	(200)
Total deferred tax liabilities	(291)	(201)
Net deferred taxes

Related Party (Details)

Related Party (Details) $ / shares in Units, € in Thousands

1 Months Ended

3 Months Ended

12 Months Ended

Jun. 22, 2024 shares

Apr. 22, 2024 shares

Mar. 19, 2024 USD ($) $ / shares shares

Jan. 03, 2024 USD ($) shares

Dec. 18, 2023 shares

Aug. 08, 2023 USD ($)

Sep. 26, 2022 USD ($)

May 15, 2021 USD ($)

Jan. 31, 2024 USD ($) $ / shares shares

Jan. 31, 2024 EUR (€) shares

Jul. 31, 2023 USD ($)

Mar. 31, 2024 $ / shares shares

Dec. 31, 2023 USD ($) $ / shares shares

Jan. 31, 2024 EUR (€)

Dec. 22, 2023 USD ($)

Oct. 31, 2023

Feb. 28, 2023

Dec. 31, 2022 $ / shares

Jun. 30, 2022

Related Party [Line Items]

Percentage of shareholder

5%

80%

Sponsor loan | $

$ 350,000

$ 350,000

Exchange for shares of the company’s common stock (in Shares) | shares

225,000

225,000

Monthly fee | $

$ 16,000

$ 11,000

Convertible promissory note | $

$ 1,100,000

Stated interest rate

10%

0%

Restricted common stock (in Shares) | shares

7,765,000

7,765,000

Common stock pare value (in Dollars per share) | $ / shares

$ 0.0001

$ 0.0001

$ 0.0001

Payments settlements | €

€ 8

Unsecured Promissory Note [Member]

Related Party [Line Items]

Promissory note issued | $

$ 850,000

Promissory Note [Member]

Related Party [Line Items]

Promissory note issued | $

$ 650,000

Stated interest rate

0%

2.50%

2.50%

Restricted Common Stock [Member]

Related Party [Line Items]

Convertible promissory note

$ 938,000

€ 850

Stated interest rate

10%

10%

Conversion of debt | $

$ 1,000,000

$ 1,000,000

Restricted Stock [Member] | Restricted Common Stock [Member]

Related Party [Line Items]

Debt converted into shares (in Shares) | shares

1,320,000

1,320,000

1,320,000

Common Stock [Member]

Related Party [Line Items]

Shares of common stock (in Shares) | shares

277,778

2,796,554

Nordic ESG [Member]

Related Party [Line Items]

Common stock pare value (in Dollars per share) | $ / shares

$ 1.23

Alternus Energy Group Plc [Member]

Related Party [Line Items]

Percentage of shareholder

80%

Sponsor [Member]

Related Party [Line Items]

Percentage of shareholder

11%

Impact Fund SCSp [Member] | Maximum [Member]

Related Party [Line Items]

Ownership percentage

80%

80%

Impact Fund SCSp [Member] | Minimum [Member]

Related Party [Line Items]

Ownership percentage

72%

72%

Sponsor [Member]

Related Party [Line Items]

Percentage of shareholder

11%

Restricted common stock (in Shares) | shares

225,000

Common stock pare value (in Dollars per share) | $ / shares

$ 0.47

Payments settlements | $

$ 1,400,000

Forecast [Member]

Related Party [Line Items]

Shares other than restricted from selling (in Shares) | shares

1,437,500

Forecast [Member] | Alternus Energy Group Plc [Member]

Related Party [Line Items]

Shares other than restricted from selling (in Shares) | shares

1,437,500

1,437,500

Related Party (Details) - Sched

Related Party (Details) - Schedule of Transactions with Directors - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Schedule of Transaction with Directors [Abstract]
Loan from Vestco, a related party to Board member and CEO Vincent Browne		$ 210	$ 210
Final payment made to Vestco on November 16, 2023			(210)
Total		$ 210

Related Party (Details) - Sch_2

Related Party (Details) - Schedule of Director's Renumeration - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Schedule of Director's Remuneration [Line Items]
Total	$ 362	$ 74	$ 606	$ 315
Remuneration in respect of services as directors [Member]
Schedule of Director's Remuneration [Line Items]
Total	362	74	606	315
Remuneration in respect to long term incentive schemes [Member]
Schedule of Director's Remuneration [Line Items]
Total

Subsequent Events (Details)

Subsequent Events (Details)

3 Months Ended

12 Months Ended

May 01, 2024 USD ($)

May 01, 2024 EUR (€)

Apr. 30, 2024 USD ($) shares

Apr. 30, 2024 EUR (€) shares

Apr. 24, 2024 shares

Apr. 19, 2024 USD ($) $ / shares shares

Mar. 19, 2024 USD ($) $ / shares shares

Feb. 26, 2024 USD ($)

Feb. 26, 2024 EUR (€)

Feb. 14, 2024 USD ($)

Feb. 14, 2024 EUR (€)

Feb. 05, 2024 USD ($) $ / shares shares

Jan. 31, 2024 USD ($)

Jan. 31, 2024 EUR (€)

Jan. 19, 2024 USD ($)

Jan. 19, 2024 EUR (€)

Jan. 16, 2024 USD ($)

Jan. 16, 2024 EUR (€)

Jan. 11, 2024 $ / shares shares

Jan. 03, 2024 USD ($) shares

Aug. 08, 2023 USD ($)

Feb. 28, 2023

Jun. 30, 2022

Mar. 31, 2024 EUR (€)

Dec. 31, 2023 USD ($) $ / shares shares

Dec. 31, 2022 USD ($)

May 08, 2024 $ / shares shares

May 06, 2024 USD ($)

Mar. 31, 2024 $ / shares shares

Mar. 20, 2024 $ / shares

Feb. 20, 2024 $ / shares shares

Jan. 23, 2024 $ / shares shares

Nov. 30, 2021

Subsequent Events [Line Items]

Convertible note holder converted all of the principal

$ 2,005,000

Shares issued (in Shares) | shares

2,796,554

2,796,554

100,000

81,301

Price per share (in Dollars per share) | $ / shares

$ 10

$ 10

$ 0.35

$ 1.01

Percentage of shareholder

0.10%

Warrants to purchase shares (in Shares) | shares

90,000

Warrants exercisable (in Dollars per share) | $ / shares

$ 0.01

Fair value

$ 86,000

Repayment of sponsor's debt

$ 9,282,000

Share price (in Dollars per share) | $ / shares

$ 5

Percentage of Interest rate

50%

50%

7%

Exercise price per share (in Dollars per share) | $ / shares

$ 0.07

Average Percentage

9.50%

Exercised options (in Euro)

$ 68,500,000

€ 59,100,000

Promissory Note [Member]

Subsequent Events [Line Items]

Outstanding amount owed

$ 650,000

Maturity date

May 31, 2024

Jun. 29, 2023

Warrants exercisable (in Dollars per share) | $ / shares

$ 0.01

$ 0.01

VWAP [Member]

Subsequent Events [Line Items]

Average Percentage

92%

Common Stock [Member]

Subsequent Events [Line Items]

Convertible note holder converted all of the principal

Shares of restricted common stock (in Shares) | shares

225,000

Shares issued (in Shares) | shares

225,000

Call Option [Member]

Subsequent Events [Line Items]

Exercise call options | €

€ 216,000

Subsequent Event [Member]

Subsequent Events [Line Items]

Convertible note holder converted all of the principal

$ 2,160,000

$ 1,000,000

Shares issued (in Shares) | shares

330,000

Price per share (in Dollars per share) | $ / shares

$ 0.35

Percentage of shareholder

71.80%

Amount received on sale

$ 7,000,000

€ 6,500,000

Outstanding amount owed

$ 50,000

Warrants exercisable (in Dollars per share) | $ / shares

$ 0.01

Fair value

$ 86,000

Repayment of sponsor's debt

$ 60,200,000

$ 1,400,000

Percentage of Interest rate

7%

Exercise price per share (in Dollars per share) | $ / shares

$ 0.48

Gross Proceeds

$ 2,000,000

Exercised options (in Euro)

$ 68,500,000

€ 59,100,000,000,000

Subsequent Event [Member] | Promissory Note [Member]

Subsequent Events [Line Items]

Maturity date

Feb. 28, 2025

Subsequent Event [Member] | Maximum [Member]

Subsequent Events [Line Items]

Percentage of shareholder

80%

Subsequent Event [Member] | Maximum [Member] | Promissory Note [Member]

Subsequent Events [Line Items]

Outstanding amount owed

0.527

$ 3.55

Subsequent Event [Member] | Minimum [Member]

Subsequent Events [Line Items]

Shares issued (in Shares) | shares

100,000

Percentage of shareholder

72%

Subsequent Event [Member] | Minimum [Member] | Promissory Note [Member]

Subsequent Events [Line Items]

Outstanding amount owed

$ 241,109

$ 3.2

Subsequent Event [Member] | Poland [Member]

Subsequent Events [Line Items]

Amount received on sale

$ 59,100,000

€ 54,400,000

Exercised options (in Euro) | €

€ 1,000,000

Subsequent Event [Member] | Purchase Agreement [Member]

Subsequent Events [Line Items]

Percentage of Interest rate

8%

Subsequent Event [Member] | Common Stock [Member]

Subsequent Events [Line Items]

Share price (in Dollars per share) | $ / shares

$ 1

Subsequent Event [Member] | Call Option [Member]

Subsequent Events [Line Items]

Exercise call options

$ 6,200,000

€ 5,700,000

$ 69,500,000

€ 59,100,000

Subsequent Event [Member] | Solis Bond Company DAC [Member]

Subsequent Events [Line Items]

Exercised options (in Euro) | €

€ 1,000,000

Subsequent Event [Member] | Restricted Common Stock [Member]

Subsequent Events [Line Items]

Shares of restricted common stock (in Shares) | shares

1,320,000

Shares issued (in Shares) | shares

15,000,000

15,000,000

225,000

7,765,000

100,000

100,000

81,301

Price per share (in Dollars per share) | $ / shares

$ 0.47

$ 1.23

$ 0.35

$ 0.35

$ 1.01

Warrants to purchase shares (in Shares) | shares

90,000

Forecast [Member]

Subsequent Events [Line Items]

Exercised options (in Euro)

$ 1,069,985

€ 1,000,000

Market value received

$ 35,000,000

Forecast [Member] | VWAP [Member]

Subsequent Events [Line Items]

Market value received

$ 35,000,000

Warrant [Member] | Subsequent Event [Member]

Subsequent Events [Line Items]

Purchares shares (in Shares) | shares

2,411,088

Organization and Formation (D_3

Organization and Formation (Details) - Schedule of Operating Subsidiaries	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Power Clouds S.r.l. [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	SPV	SPV
Date Acquired / Established	31 March 2015	31 March 2015
ALCE Ownership	Solis Bond Company DAC	Solis Bond Company DAC
Country of Operations	Romania	Romania
F.R.A.N. Energy Investment S.r.l. [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	SPV	SPV
Date Acquired / Established	31 March 2015	31 March 2015
ALCE Ownership	Solis Bond Company DAC	Solis Bond Company DAC
Country of Operations	Romania	Romania
PC-Italia-01 S.r.l. [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	Sub-Holding SPV	Sub-Holding SPV
Date Acquired / Established	15 May 2015	15 May 2015
ALCE Ownership	AEG MH 02 Limited	AEG MH 02 Limited
Country of Operations	Italy	Italy
PC-Italia-03 S.r.l. [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	SPV	SPV
Date Acquired / Established	1 July 2020	1 July 2020
ALCE Ownership	AEG MH 02 Limited	AEG MH 02 Limited
Country of Operations	Italy	Italy
PC-Italia-04 S.r.l. [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	SPV	SPV
Date Acquired / Established	15 July 2020	15 July 2020
ALCE Ownership	AEG MH 02 Limited	AEG MH 02 Limited
Country of Operations	Italy	Italy
Solis Bond Company DAC [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	Holding Company	Holding Company
Date Acquired / Established	16 October 2020	16 October 2020
ALCE Ownership	AEG JD 03 Limited	AEG JD 03 Limited
Country of Operations	Ireland	Ireland
ALT US 03, LLC [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	LLC
Date Acquired / Established	4 May 2022
ALCE Ownership	ALT US 03 LLC
Country of Operations	USA
Alternus Energy Americas Inc. [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	Holding Company	Holding Company
Date Acquired / Established	10 May 2021	10 May 2021
ALCE Ownership	Alternus Energy Group Pl	Alternus Energy Group Pl
Country of Operations	USA	USA
LJG Green Source Energy Beta S.r.l [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	SPV	SPV
Date Acquired / Established	29 July 2021	29 July 2021
ALCE Ownership	Solis Bond Company DAC	Solis Bond Company DAC
Country of Operations	Romania	Romania
Ecosfer Energy S.r.l. [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	SPV	SPV
Date Acquired / Established	30 July 2021	30 July 2021
ALCE Ownership	Solis Bond Company DAC	Solis Bond Company DAC
Country of Operations	Romania	Romania
Lucas EST S.r.l. [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	SPV	SPV
Date Acquired / Established	30 July 2021	30 July 2021
ALCE Ownership	Solis Bond Company DAC	Solis Bond Company DAC
Country of Operations	Romania	Romania
Risorse Solari I S.r.l. [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	SPV	SPV
Date Acquired / Established	28 September 2019	28 September 2019
ALCE Ownership	AEG MH 02 Limited	AEG MH 02 Limited
Country of Operations	Italy	Italy
Risorse Solari III S.r.l. [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	SPV	SPV
Date Acquired / Established	3 August 2021	3 August 2021
ALCE Ownership	AEG MH 02 Limited	AEG MH 02 Limited
Country of Operations	Italy	Italy
Alternus Iberia S.L. [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	SPV	SPV
Date Acquired / Established	4 August 2021	4 August 2021
ALCE Ownership	AEG MH 02 Limited	AEG MH 02 Limited
Country of Operations	Spain	Spain
AED Italia-01 S.r.l. [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	SPV	SPV
Date Acquired / Established	22 October 2021	22 October 2021
ALCE Ownership	AEG MH 02 Limited	AEG MH 02 Limited
Country of Operations	Italy	Italy
AED Italia-02 S.r.l. [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	SPV	SPV
Date Acquired / Established	22 October 2021	22 October 2021
ALCE Ownership	AEG MH 02 Limited	AEG MH 02 Limited
Country of Operations	Italy	Italy
AED Italia-03 S.r.l. [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	SPV	SPV
Date Acquired / Established	22 October 2021	22 October 2021
ALCE Ownership	AEG MH 02 Limited	AEG MH 02 Limited
Country of Operations	Italy	Italy
AED Italia-04 S.r.l. [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	SPV	SPV
Date Acquired / Established	22 October 2021	22 October 2021
ALCE Ownership	AEG MH 02 Limited	AEG MH 02 Limited
Country of Operations	Italy	Italy
AED Italia-05 S.r.l. [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	SPV	SPV
Date Acquired / Established	22 October 2021	22 October 2021
ALCE Ownership	AEG MH 02 Limited	AEG MH 02 Limited
Country of Operations	Italy	Italy
ALT US 01 LLC [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	SPV	SPV
Date Acquired / Established	6 December 2021	6 December 2021
ALCE Ownership	Alternus Energy Americas Inc.	Alternus Energy Americas Inc.
Country of Operations	USA	USA
AEG MH 01 Limited [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	Holding Company	Holding Company
Date Acquired / Established	8 March 2022	8 March 2022
ALCE Ownership	Alternus Lux 01 S.a.r.l.	Alternus Lux 01 S.a.r.l.
Country of Operations	Ireland	Ireland
AEG MH 02 Limited [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	Holding Company	Holding Company
Date Acquired / Established	8 March 2022	8 March 2022
ALCE Ownership	AEG JD 03 Limited	AEG JD 03 Limited
Country of Operations	Ireland	Ireland
ALT US 02 LLC [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	Holding Company	Holding Company
Date Acquired / Established	8 March 2022	8 March 2022
ALCE Ownership	Alternus Energy Americas Inc.	Alternus Energy Americas Inc.
Country of Operations	USA	USA
AEG JD 01 Limited [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	Holding Company	Holding Company
Date Acquired / Established	16 March 2022	16 March 2022
ALCE Ownership	AEG MH 03 Limited	AEG MH 03 Limited
Country of Operations	Ireland	Ireland
Alternus Europe Limited (f/k/a AEG JD 03 Limited) [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	Holding Company
Date Acquired / Established	21 March 2022
ALCE Ownership	Alternus Lux 01 S.a.r.l.
Country of Operations	Ireland
Alt Spain 03, S.L.U. [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	SPV	SPV
Date Acquired / Established	31 May 2022	31 May 2022
ALCE Ownership	Alt Spain Holdco S.L.	Alt Spain Holdco S.L.
Country of Operations	Spain	Spain
AEG MH 03 Limited [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	Holding Company	Holding Company
Date Acquired / Established	10 June 2022	10 June 2022
ALCE Ownership	AEG MH 01 Limited	AEG MH 01 Limited
Country of Operations	Ireland	Ireland
Lightwave Renewables, LLC [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	SPV	SPV
Date Acquired / Established	29 June 2022	Acquired 29 June 2022 (Est. 17 December 2020)
ALCE Ownership	ALT US 02 LLC	ALT US 02 LLC
Country of Operations	USA	USA
Alt Spain Holdco, S.L.U. [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	Holding Company
Date Acquired / Established	Acquired 14 July 2022
ALCE Ownership	AEG MH 02 Limited
Country of Operations	Spain
AED Italia-06 S.r.l. [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	SPV	SPV
Date Acquired / Established	2 August 2022	2 August 2022
ALCE Ownership	AEG MH 02 Limited	AEG MH 02 Limited
Country of Operations	Italy	Italy
AED Italia-07 S.r.l.[Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	SPV	SPV
Date Acquired / Established	2 August 2022	2 August 2022
ALCE Ownership	AEG MH 02 Limited	AEG MH 02 Limited
Country of Operations	Italy	Italy
AED Italia-08 S.r.l. [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	SPV	SPV
Date Acquired / Established	5 August 2022	5 August 2022
ALCE Ownership	AEG MH 02 Limited	AEG MH 02 Limited
Country of Operations	Italy	Italy
ALT US 04 LLC [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	Holding Company
Date Acquired / Established	14 September 2022
ALCE Ownership	Alternus Energy Americas Inc.
Country of Operations	USA
Alternus LUX 01 S.a.r.l. [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	Holding Company	Holding Company
Date Acquired / Established	5 October 2022	5 October 2022
ALCE Ownership	Alternus Energy Group Plc	Alternus Energy Group Plc
Country of Operations	Luxembourg	Luxembourg
Alt Spain 04, S.L.U. [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	SPV	SPV
Date Acquired / Established	May 2022	May 2022
ALCE Ownership	Alt Spain Holdco, S.L.U.	Alt Spain Holdco, S.L.U.
Country of Operations	Spain	Spain
Alt Alliance LLC [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	Holding Company	Holding Company
Date Acquired / Established	September 2023	September 2023
ALCE Ownership	Alternus Energy Amercias Inc.	Alternus Energy Amercias Inc.
Country of Operations	USA	USA
ALT US 05 LLC [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	Holding Company	Holding Company
Date Acquired / Established	September 2023	September 2023
ALCE Ownership	Alternus Energy Americas Inc.	Alternus Energy Americas Inc.
Country of Operations	USA	USA
ALT US 06 LLC [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	Holding Company	Holding Company
Date Acquired / Established	October 2023	October 2023
ALCE Ownership	Alternus Energy Americas Inc.	Alternus Energy Americas Inc.
Country of Operations	USA	USA
ALT US 07 LLC [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	Holding Company
Date Acquired / Established	November 2023
ALCE Ownership	Alternus Energy Americas Inc.
Country of Operations	USA
AEG MH 04 Limited [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	Holding Company
Date Acquired / Established	January 2024
ALCE Ownership	AEG MH 04 Limited
Country of Operations	Ireland
ALT US 08 LLC [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	Holding Company
Date Acquired / Established	January 2024
ALCE Ownership	Alternus Energy Americas Inc.
Country of Operations	USA
ALT US AM LLC [Member]
Schedule of Operating Subsidiaries [Line Items[
Principal Activity	Holding Company
Date Acquired / Established	March 2024
ALCE Ownership	Alternus Energy Americas Inc.
Country of Operations	USA

Business Combination (Details_2

Business Combination (Details) - Schedule of Common Stock Outstanding After the Closing of the Business Combination	Mar. 31, 2024 shares
Schedule of Common Stock Outstanding After the Closing of the Business Combination [Line Items]
Total common stock outstanding	71,905,363
Exchange of CLIN common stock subject to possible redemption that was not redeemed for Alternus Clean Energy Inc. common stock [Member]
Schedule of Common Stock Outstanding After the Closing of the Business Combination [Line Items]
Total common stock outstanding	127,142
Exchange of public share rights held by CLIN shareholders for Alternus Clean Energy Inc. common stock [Member]
Schedule of Common Stock Outstanding After the Closing of the Business Combination [Line Items]
Total common stock outstanding	2,300,000
Issuance of Alternus Clean Energy, Inc. common stock to promissory note holders [Member]
Schedule of Common Stock Outstanding After the Closing of the Business Combination [Line Items]
Total common stock outstanding	400,000
Exchange of CLIN Class A common stock held by CLIN Sponsor for Alternus Clean Energy Inc. common stock [Member]
Schedule of Common Stock Outstanding After the Closing of the Business Combination [Line Items]
Total common stock outstanding	8,556,667
Subtotal - Business Combination, net of redemptions [Member]
Schedule of Common Stock Outstanding After the Closing of the Business Combination [Line Items]
Total common stock outstanding	11,383,809
Issuance of shares under the FPA [Member]
Schedule of Common Stock Outstanding After the Closing of the Business Combination [Line Items]
Total common stock outstanding	1,496,234
Shares purchased by the accredited investor under the FPA [Member]
Schedule of Common Stock Outstanding After the Closing of the Business Combination [Line Items]
Total common stock outstanding	1,300,320
Issuance of Alternus Clean Energy Inc. common stock to Alternus Energy Group Plc. on the Closing Date [Member]
Schedule of Common Stock Outstanding After the Closing of the Business Combination [Line Items]
Total common stock outstanding	57,500,000
Issuance of Alternus Clean Energy Inc. common stock to the CLIN Sponsor as a holder of CLIN convertible notes on the Closing Date [Member]
Schedule of Common Stock Outstanding After the Closing of the Business Combination [Line Items]
Total common stock outstanding	225,000

Fair Value Measurements (Deta_5

Fair Value Measurements (Details) - Schedule of Balances of the Forward Purchase Agreement - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Schedule of Balances of the Forward Purchase Agreement [Line Items]
Forward Purchase Agreement		$ 483
Total		483
Level 1 [Member]
Schedule of Balances of the Forward Purchase Agreement [Line Items]
Forward Purchase Agreement
Total
Level 2 [Member]
Schedule of Balances of the Forward Purchase Agreement [Line Items]
Forward Purchase Agreement
Total
Level 3 [Member]
Schedule of Balances of the Forward Purchase Agreement [Line Items]
Forward Purchase Agreement		483
Total		$ 483

Fair Value Measurements (Deta_6

Fair Value Measurements (Details) - Schedule of Changes of the Forward Purchase Agreement with Significant Unobservable Inputs - Level 3 [Member] - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance	$ 483
Recognition of Forward Purchase Agreement Asset		17,125
Change in fair value	(483)	(16,642)
Balance		$ 483

Fair Value Measurements (Deta_7

Fair Value Measurements (Details) - Schedule of the Forward Purchase Agreement Using a Monte Carlo Simulation Valuation Model - Forward Purchase Agreement Asset [Member]	Mar. 31, 2024	Dec. 31, 2023
Rik-free rate [Member]
Schedule of the Forward Purchase Agreement Using a Monte Carlo Simulation Valuation Model [Line Items]
Forward Purchase Agreement Asset Input	4.5%	4%
Underlying stock price [Member]
Schedule of the Forward Purchase Agreement Using a Monte Carlo Simulation Valuation Model [Line Items]
Forward Purchase Agreement Asset Input	$0.43	$1.50
Expected volatility [Member]
Schedule of the Forward Purchase Agreement Using a Monte Carlo Simulation Valuation Model [Line Items]
Forward Purchase Agreement Asset Input	92.7%	75%
Term [Member]
Schedule of the Forward Purchase Agreement Using a Monte Carlo Simulation Valuation Model [Line Items]
Forward Purchase Agreement Asset Input	2.73 years	2.98 years
Dividend yield [Member]
Schedule of the Forward Purchase Agreement Using a Monte Carlo Simulation Valuation Model [Line Items]
Forward Purchase Agreement Asset Input	0%	0%

Accounts Receivable (Details)_2

Accounts Receivable (Details) - Schedule of Accounts Receivables and Unbilled Energy Incentives - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Schedule of Accounts Receivables and Unbilled Energy Incentives [Abstract]
Accounts receivable	$ 2,119	$ 651	$ 3,335
Unbilled energy incentives earned	6,048	5,607	4,954
Total	$ 8,167	$ 6,258	$ 8,289

Prepaid Expenses and Other Cu_4

Prepaid Expenses and Other Current Assets (Details) - Schedule of Prepaid Expenses and Other Current Assets - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Schedule of Prepaid Expenses and Other Current Assets [Abstract]
Prepaid expenses and other current assets	$ 2,501	$ 2,602	$ 328
Accrued revenue		6	294
Other receivable	522	736	860
Total	$ 3,023	$ 3,344	$ 1,482

Property and Equipment, Net (_3

Property and Equipment, Net (Details) - Schedule of Property and Equipment - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Schedule of Property and Equipment [Line Items]
Total property and equipment	$ 69,319	$ 68,628	$ 79,096
Less: Accumulated depreciation	(7,714)	(7,326)	(10,143)
Total	61,605	61,302	68,953
Solar energy facilities [Member]
Schedule of Property and Equipment [Line Items]
Total property and equipment	55,737	55,318	75,009
Building [Member]
Schedule of Property and Equipment [Line Items]
Total property and equipment	500	511	107
Land [Member]
Schedule of Property and Equipment [Line Items]
Total property and equipment	6	511	497
Furniture and fixtures [Member]
Schedule of Property and Equipment [Line Items]
Total property and equipment	207	210	49
Asset retirement [Member]
Schedule of Property and Equipment [Line Items]
Total property and equipment	164	168	341
Construction in progress [Member]
Schedule of Property and Equipment [Line Items]
Total property and equipment	$ 12,705	$ 12,421	$ 3,093

Capitalized Development Cost _5

Capitalized Development Cost and Other Long-Term Assets (Details) - Schedule of Capitalized Cost and Other Long-Term Assets - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Schedule of Capitalized Cost and Other Long-Term Assets [Abstract]
Capitalized development cost	$ 6,351	$ 6,216	$ 2,146
Other receivables	1,000	1,483
Total	$ 7,351	$ 7,699	$ 2,146

Deferred Income (Details) - S_2

Deferred Income (Details) - Schedule of Deferred Income - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Schedule of Deferred Income [Abstract]
Deferred income beginning balance	$ 5,607	$ 4,954	$ 3,139
Green certificates received	2,030	10,663	10,729
Green certificates sold	(1,468)	(10,169)	(8,849)
Foreign exchange gain/(loss)	(121)	159	(65)
Deferred income ending balance	$ 6,048	$ 5,607	$ 4,954

Accrued Liabilities (Details)_2

Accrued Liabilities (Details) - Schedule of Accrued Liabilities - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Schedule of Accrued Liabilities [Abstract]
Accrued legal	$ 7,258	$ 8,684
Accrued interest	6,294	5,516	1,992
Accrued financing cost	2,397	3,537
Accrued construction expense	363	2,134
Accrued transaction cost - business combination	261	1,527
Accrued audit fees	150	800
Accrued payroll	215	148	501
Other accrued expenses	2,094	2,064	978
Total	$ 19,032	$ 24,410	$ 3,471

Taxes Recoverable and Payable_3

Taxes Recoverable and Payable (Details) - Schedule of Taxes Recoverable and Payable - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Schedule of Taxes Recoverable and Payable [Abstract]
Taxes recoverable	$ 683	$ 631	$ 1,388
Less: Taxes payable	(13)	(14)	(616)
Total	$ 670	$ 617	$ 772

Green Bonds, Convertible and _8

Green Bonds, Convertible and Non-convertible Promissory Notes (Details) - Schedule of Debt Balances - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Total debt	$ 118,787	$ 198,434
Less current maturities	(118,787)	(198,434)
Long term debt, net of current maturities
Current Maturities	118,787	198,434	$ 162,967
Less current debt discount	(908)	(892)
Current Maturities net of debt discount	117,879	197,542
Senior Secured Green Bonds [Member]
Debt Instrument [Line Items]
Total debt	87,264	166,122
Senior Secured debt and promissory notes secured [Member]
Debt Instrument [Line Items]
Total debt	$ 31,523	$ 32,312

Leases (Details) - Schedule o_3

Leases (Details) - Schedule of Key Components of the Company's Operating Leases - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Schedule of Key Components of the Company's Operating Leases [Abstract]
Operating Lease - Operating Cash Flows (Fixed Payments)	$ 75	$ 189	$ 99
Operating Lease - Operating Cash Flows (Liability Reduction)	61	129	54
New ROU Assets - Operating Leases		$ 409	$ 8,482
Weighted Average Lease Term - Operating Leases (years)	12 years 11 months 26 days	13 years 2 months 26 days	7 years 18 days
Weighted Average Discount Rate - Operating Leases	7.65%	7.65%	7.10%

Leases (Details) - Schedule o_4

Leases (Details) - Schedule of Maturities of Lease Liabilities - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Five-year lease schedule:
2024 Apr 1 – Dec 31	$ 154
2025	235	$ 231
2026	241	237
2027	247	242
2028	215	248
Thereafter	2,021	216
Total lease payments	3,113	3,238
Less imputed interest	(1,748)	(1,811)
Total	$ 1,365	$ 1,427

Asset Retirement Obligations _3

Asset Retirement Obligations (Details) - Schedule of Asset Retirement Obligations - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Schedule of Asset Retirement Obligations [Abstract]
ARO Liability - Balance	$ 197	$ 397	$ 411
Additional obligations incurred
Disposals		(235)
Accretion expense	3	24	20
Foreign exchange gain/(loss)	(4)	11
ARO Liability - Balance	$ 196	$ 197	$ 397

Development Cost (Details) - _2

Development Cost (Details) - Schedule of Development Cost - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Schedule of Development Cost [Abstract]
Miscellaneous development cost	$ 7
Total	$ 7	$ 111	$ 798	$ 11,372

Discontinued Operations Sold _4

Discontinued Operations Sold (Details) - Schedule of Sale of the Netherlands Assets - USD ($) $ in Thousands	Feb. 21, 2024	Jan. 19, 2024	Dec. 31, 2023	Dec. 31, 2022
Poland [Member]
Assets:
Cash & cash equivalents		$ 630	$ 630	$ 431
Other current assets		442	443	1,105
Property, plant, and equipment, net		63,107	63,107	69,656
Operating leases, non-current - assets		5,923	5,923	5,378
Total assets held for sale		70,102	70,103	76,570
Liabilities:
Accounts payable		2,933	2,935	1,760
Operating leases, current – liabilities		281	281	233
Other current liabilities		25	1,549	1,157
Operating leases, non-current - liabilities		5,798	5,798	4,995
Other non-current liabilities		985	985	824
Total liabilities		10,022	11,548	8,969
Net assets held for sale		$ 60,080	58,555	67,601
Netherlands [Member]
Assets:
Cash & cash equivalents	$ 75		155	13
Accounts receivable, net			99	487
Other current assets	178		58	82
Property, plant, and equipment, net	7,669		7,845	7,984
Operating leases, non-current - assets	1,441		1,469	1,438
Other non-current assets	1,192		1,214	1,176
Total assets held for sale	10,555		10,840	11,180
Liabilities:
Accounts payable	945		925	23
Operating leases, current – liabilities	55		55	52
Other current liabilities	95		430	235
Operating leases, non-current - liabilities	1,273		1,301	1,312
Total liabilities	2,368		2,711	1,622
Net assets held for sale	$ 8,187		$ 8,129	$ 9,558

Discontinued Operations Sold _5

Discontinued Operations Sold (Details) - Schedule of Recognized in Discontinued Operations in the Statement of Profit or Loss - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Poland [Member]
Schedule of Recognized in Discontinued Operations in the Statement of Profit or Loss [Line Items]
Revenues	$ 106	$ 1,105	$ 7,593	$ 10,709
Operating Expenses
Cost of revenues	(101)	(936)	(3,768)	(4,104)
Depreciation, amortization, and accretion	(123)	(609)	(2,563)	(2,482)
Gain (Loss) on disposal of asset	3,484
Total operating expenses	3,260	(1,545)	(6,461)	(6,586)
Income/(loss) from discontinued operations	3,366	(440)	1,132	4,123
Other income/(expense):
Interest expense	(688)	(1,224)	(11,766)
Total other expenses	(688)	(1,224)	(5,650)	(3,893)
Income/(Loss) before provision for income taxes	2,678	(1,664)	(17,573)	(3,923)
Net income/(loss) from discontinued operations	2,678	(1,664)	(16,441)	200
Impact of discontinued operations on EPS
Net income/(loss) attributable to common stockholders, basic	2,678	(1,664)	(16,441)	179
Net income/(loss) attributable to common stockholders, diluted	$ 2,678	$ (1,664)	$ (16,441)	$ 179
Net income/(loss) per share attributable to common stockholders, basic (in Dollars per share)	$ 0.04	$ (0.03)	$ (0.28)	$ 0
Net income/(loss) per share attributable to common stockholders, diluted (in Dollars per share)	$ 0.04	$ (0.03)	$ 0	$ 0
Weighted-average common stock outstanding, basic (in Shares)	65,077,094	57,500,000	57,862,598	57,500,000
Weighted-average common stock outstanding, diluted (in Shares)	65,077,094	57,500,000	57,862,598	57,500,000
Netherlands [Member]
Schedule of Recognized in Discontinued Operations in the Statement of Profit or Loss [Line Items]
Revenues	$ 16	$ 202	$ 2,840	$ 1,596
Operating Expenses
Cost of revenues	(115)	(61)	(450)	(368)
Depreciation, amortization, and accretion	(57)	(126)	(400)	(500)
Gain (Loss) on disposal of asset	(1,334)
Total operating expenses	(1,506)	(187)	(857)	(868)
Income/(loss) from discontinued operations	(1,490)	15	1,983	728
Other income/(expense):
Interest expense	(113)	(248)
Total other expenses	(113)	(248)	(1,131)	(787)
Income/(Loss) before provision for income taxes	(1,603)	(233)	(1,193)	(787)
Net income/(loss) from discontinued operations	(1,603)	(233)	790	(59)
Impact of discontinued operations on EPS
Net income/(loss) attributable to common stockholders, basic	(1,603)	(233)	629	(59)
Net income/(loss) attributable to common stockholders, diluted	$ (1,603)	$ (233)	$ 629	$ (59)
Net income/(loss) per share attributable to common stockholders, basic (in Dollars per share)	$ (0.02)	$ 0	$ 0.01	$ 0
Net income/(loss) per share attributable to common stockholders, diluted (in Dollars per share)	$ (0.02)	$ 0	$ 0.01	$ 0
Weighted-average common stock outstanding, basic (in Shares)	65,077,094	57,500,000	57,862,598	57,500,000
Weighted-average common stock outstanding, diluted (in Shares)	65,077,094	57,500,000	57,862,598	57,500,000

Italy Sale Disclosure (Detail_3

Italy Sale Disclosure (Details) - Schedule of Remaining Balances and Results of the Italian Assets - Italy [Member] - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 28, 2023
Italy Sale Disclosure (Details) - Schedule of Remaining Balances and Results of the Italian Assets [Line Items]
Cash & cash equivalents	$ 87,000		$ 100,000	$ 295,000	$ 100,000
Other current assets	330,000		338,000	932,000
Other non-current assets	3,966,000		3,819,000	1,030,000	338,000
Total assets	4,383,000		4,257,000	21,735,000
Operating leases, non-current - assets				4,000
Accounts payable	17,000		21,000	109,000	21,000
Other current liabilities	569,000		578,000
Total liabilities	586,000		599,000	1,405,000	599,000
Net assets	3,797,000		3,658,000	1,080,000	578,000
Revenues		$ 655,000		216,000
Operating Expenses
Cost of revenues		(262,000)	(1,204,000)	(812,000)
Selling, general, and administrative	(8,000)	(42,000)	(69,000)	(77,000)
Depreciation, amortization, and accretion		(410,000)	(1,638,000)	(1,614,000)
Total operating expenses	(8,000)	(714,000)	8,412,000	2,503,000
Loss from discontinued operations	(8,000)	(59,000)	(5,501,000)
Other expense		(36,000)	(5,052,000)	851,000
Total other expenses		(36,000)	(15,000)	22,000
Loss before provision for income taxes	(8,000)	(95,000)	(5,067,000)	873,000
Income taxes
Net loss from discontinued operations	(8,000)	(95,000)	(15,000)
Impact on EPS
Net loss attributable to common stockholders, basic	(8,000)	(95,000)
Net loss attributable to common stockholders, diluted	$ (8,000)	$ (95,000)	$ (5,067,000)	$ 873,000
Net loss per share attributable to common stockholders, basic (in Dollars per share)	$ 0	$ 0	$ (5,067)	$ 873
Net loss per share attributable to common stockholders, diluted (in Dollars per share)	$ 0	$ 0	$ (5,067)	$ 873
Weighted-average common stock outstanding, basic	$ 65,077,094,000	$ 57,500,000,000	$ (90)	$ 20
Weighted-average common stock outstanding, diluted	$ 65,077,094,000	$ 57,500,000,000	$ (90)	$ 20

Shareholders' Equity (Details_2

Shareholders' Equity (Details) - Schedule of Common Stock were Issued and Outstanding - Warrant [Member] - $ / shares			3 Months Ended		12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Shareholders' Equity (Details) - Schedule of Common Stock were Issued and Outstanding [Line Items]
Warrants, Outstanding Balance	12,345,000	11,945,000	12,435,000	11,945,000	12,345,000	11,945,000
Weighted Average Exercise Price, Outstanding Balance	$ 11.22	$ 11.5	$ 11.14	$ 11.5	$ 11.22	$ 11.5
Weighted Average Remaining Contractual Term (Years), Outstanding Balance	4 years 11 months 4 days	5 years 11 months 23 days	4 years 8 months 23 days	5 years 11 months 23 days	4 years 11 months 4 days	5 years 11 months 23 days
Warrants, Exercisable	12,345,000		12,435,000	11,945,000	12,345,000
Weighted Average Exercise Price, Exercisable	$ 11.22		$ 11.14	$ 11.5	$ 11.22
Weighted Average Remaining Contractual Term (Years), Exercisable			4 years 8 months 23 days	5 years 11 months 23 days	4 years 11 months 4 days
Warrants, Issued during the quarter			90,000		400,000
Weighted Average Exercise Price, Issued during the quarter			$ 0.01		$ 0.35
Weighted Average Remaining Contractual Term (Years), Issued during the quarter			10 days		1 month 28 days
Warrants, Expired during the quarter
Weighted Average Exercise Price, Expired during the quarter
Weighted Average Remaining Contractual Term (Years), Expired during the quarter

Segment and Geographic Inform_5

Segment and Geographic Information (Details) - Schedule of Geographic Information Related to the Company’s Reportable Segments - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Schedule of Reportable Segments [Line Items]
Revenue by Segment	$ 2,302	$ 5,153
Operating Loss by Segment	(7,583)	(5,252)	$ (69,464)	$ (18,448)
Europe
Assets by Segment	84,354		185,286	178,315
Europe
Liabilities by Segment	156,073		248,540	180,897
US
Valuation on FPA Asset			2,502	554
Depreciation, amortization, and accretion	568	842	3,657	3,677
Interest expense	4,984	3,468	18,562	10,256
Net Loss	(7,583)	(5,252)	(69,464)	(18,448)
Europe [Member]
Schedule of Reportable Segments [Line Items]
Operating Loss by Segment	(2,907)	(4,310)	(46,301)	(14,977)
Energy Offtake Agreements (PPA)
EBITDA by Segment	2,258	2,122	6,874	6,537
US
Depreciation, amortization, and accretion	(699)	(1,574)	(6,563)	(6,617)
Interest expense	(4,466)	(4,858)	(23,453)	(14,876)
Net Loss	(2,907)	(4,310)	(46,301)	(14,977)
United States [Member]
Schedule of Reportable Segments [Line Items]
Operating Loss by Segment	(4,676)	(942)	(23,163)	(3,471)
Energy Offtake Agreements (PPA)
EBITDA by Segment	(2,827)	(857)	(4,560)	(3,370)
US
Valuation on FPA Asset	(483)
Depreciation, amortization, and accretion	(49)	(2)	(57)	(42)
Interest expense	(1,317)	(83)	(1,889)	(59)
Net Loss	(4,676)	(942)	(23,163)	(3,471)
Revenue by Segment [Member] | Europe [Member]
Schedule of Reportable Segments [Line Items]
Revenue by Segment	2,086	3,828
Revenue by Segment [Member] | United States [Member]
Schedule of Reportable Segments [Line Items]
Revenue by Segment	93	1,307
Revenue by Segment [Member] | Discontinued Operations [Member] | Europe [Member]
Schedule of Reportable Segments [Line Items]
Revenue by Segment	123	18
Operating Loss [Member]
Schedule of Reportable Segments [Line Items]
Operating Loss by Segment	(7,583)	(5,252)	(69,464)	(18,448)
US
Net Loss	(7,583)	(5,252)	(69,464)	(18,448)
Operating Loss [Member] | Europe [Member]
Schedule of Reportable Segments [Line Items]
Operating Loss by Segment	(2,908)	(4,310)	(46,301)	(14,978)
US
Net Loss	(2,908)	(4,310)	(46,301)	(14,978)
Operating Loss [Member] | United States [Member]
Schedule of Reportable Segments [Line Items]
Operating Loss by Segment	(4,675)	(942)	(23,163)	(3,470)
US
Net Loss	(4,675)	(942)	(23,163)	(3,470)
Assets by Segment [Member] | Europe [Member]
Europe
Assets by Segment	62,944		162,328	173,080
Assets by Segment [Member] | Europe [Member] | Fixed Assets [Member]
Europe
Assets by Segment	42,209		125,600	141,862
Assets by Segment [Member] | Europe [Member] | Other Assets [Member]
Europe
Assets by Segment	20,735		36,728	31,218
Assets by Segment [Member] | United States [Member]
Europe
Assets by Segment	21,410		22,958	5,235
Assets by Segment [Member] | United States [Member] | Fixed Assets [Member]
Europe
Assets by Segment	6,556		5,119	599
Assets by Segment [Member] | United States [Member] | Other Assets [Member]
Europe
Assets by Segment	14,854		17,839	4,636
Liabilities by Segment [Member] | Europe [Member]
Europe
Liabilities by Segment	127,794		219,672	175,117
Liabilities by Segment [Member] | Europe [Member] | Debt [Member]
Europe
Liabilities by Segment	99,686		180,294	155,896
Liabilities by Segment [Member] | Europe [Member] | Other Liabilities [Member]
Europe
Liabilities by Segment	28,108		39,378	19,221
Liabilities by Segment [Member] | United States [Member]
Europe
Liabilities by Segment	28,279		28,868	5,780
Liabilities by Segment [Member] | United States [Member] | Debt [Member]
Europe
Liabilities by Segment	16,582		17,247	2,793
Liabilities by Segment [Member] | United States [Member] | Other Liabilities [Member]
Europe
Liabilities by Segment	11,697		11,621	2,987
Geographic Information by Segment [Member]
Energy Offtake Agreements (PPA)
EBITDA by Segment	(569)	1,265	$ 2,314	$ 3,167
Country Renewable Programs [Member] | Revenue by Product Type [Member]
Schedule of Reportable Segments [Line Items]
Revenue by Segment	122	1,266
Country Renewable Programs [Member] | Revenue by Product Type [Member] | Europe [Member]
Schedule of Reportable Segments [Line Items]
Revenue by Segment	29	1,248
Country Renewable Programs [Member] | Revenue by Product Type [Member] | United States [Member]
Schedule of Reportable Segments [Line Items]
Revenue by Segment	93	18
Green Certificates [Member] | Revenue by Product Type [Member]
Schedule of Reportable Segments [Line Items]
Revenue by Segment	1,575	1,880
Green Certificates [Member] | Revenue by Product Type [Member] | Europe [Member]
Schedule of Reportable Segments [Line Items]
Revenue by Segment	1,575	1,880
Green Certificates [Member] | Revenue by Product Type [Member] | United States [Member]
Schedule of Reportable Segments [Line Items]
Revenue by Segment
Energy Offtake Agreements [Member] | Revenue by Product Type [Member]
Schedule of Reportable Segments [Line Items]
Revenue by Segment	605	2,007
Energy Offtake Agreements [Member] | Revenue by Product Type [Member] | Europe [Member]
Schedule of Reportable Segments [Line Items]
Revenue by Segment	605	2,007
Energy Offtake Agreements [Member] | Revenue by Product Type [Member] | United States [Member]
Schedule of Reportable Segments [Line Items]
Revenue by Segment

Related Party (Details) - Sch_3

Related Party (Details) - Schedule of Transactions with Directors - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Schedule of Transaction with Directors [Abstract]
Loan from Vestco, a related party to Board member and CEO Vincent Browne		$ 210	$ 210
Total		$ 210

Related Party (Details) - Sch_4

Related Party (Details) - Schedule of Director's Remuneration - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Related Party (Details) - Schedule of Director's Remuneration [Line Items]
Total	$ 362	$ 74	$ 606	$ 315
Remuneration in respect of services as directors [Member]
Related Party (Details) - Schedule of Director's Remuneration [Line Items]
Total	362	74	606	315
Remuneration in respect to long term incentive schemes [Member]
Related Party (Details) - Schedule of Director's Remuneration [Line Items]
Total