Tecogen (TGEN) 10-Q 14 Aug 17 2017 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2017	Jul. 31, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	TECOGEN INC.
Entity Central Index Key	1,537,435
Current Fiscal Year End Date	--12-31
Entity Filer Category	Smaller Reporting Company
Document Type	10-Q
Document Period End Date	Jun. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		24,714,989

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($)	Jun. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 3,317,928	$ 3,721,765
Accounts receivable, net	8,868,157	8,630,418
Unbilled revenue	3,239,588	2,269,645
Inventory, net	6,099,770	4,774,264
Due from related party	378,296	260,988
Prepaid and other current assets	823,629	401,876
Total current assets	22,727,368	20,058,956
Property, plant and equipment, net	15,725,008	517,143
Intangible assets, net	2,098,484	1,065,967
Excess of cost over fair value of net assets acquired	12,570,809	0
Goodwill	40,870	40,870
Other assets	2,423,510	2,058,425
TOTAL ASSETS	55,586,049	23,741,361
Current liabilities:
Accounts payable	4,501,662	3,367,481
Accrued expenses	1,899,769	1,378,258
Deferred revenue	1,183,350	876,765
Loan due to related party	850,000	0
Interest payable, related party	26,548	0
Total current liabilities	8,461,329	5,622,504
Long-term liabilities:
Deferred revenue, net of current portion	449,741	459,275
Senior convertible promissory note, related party	3,148,898	3,148,509
Unfavorable contract liability	10,304,451	0
Total liabilities	22,364,419	9,230,288
Commitments and contingencies
Tecogen Inc. shareholders’ equity:
Common stock, $0.001 par value; 100,000,000 shares authorized; 24,711,989 and 19,981,912 issued and outstanding at June 30, 2017 and December 31, 2016, respectively	24,712	19,982
Additional paid-in capital	56,027,038	37,334,773
Accumulated other comprehensive loss-investment securities	(224,359)	0
Accumulated deficit	(23,092,431)	(22,843,682)
Total Tecogen Inc. stockholders’ equity	32,734,960	14,511,073
Noncontrolling interest	486,670	0
Total stockholders’ equity	33,221,630	14,511,073
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	$ 55,586,049	$ 23,741,361

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	24,711,989	19,981,912
Common stock, shares outstanding	24,711,989	19,981,912

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Revenues
Products	$ 3,116,198	$ 2,408,860	$ 5,923,543	$ 4,675,008
Services	3,700,150	3,278,448	7,739,570	6,087,815
Energy production	774,192	0	774,192	0
Total revenues	7,590,540	5,687,308	14,437,305	10,762,823
Cost of sales
Products	1,965,881	1,767,052	3,722,730	3,319,768
Services	2,307,494	1,817,362	4,482,739	3,620,817
Energy production	330,543	0	330,543	0
Total cost of sales	4,603,918	3,584,414	8,536,012	6,940,585
Gross profit	2,986,622	2,102,894	5,901,293	3,822,238
Operating expenses
General and administrative	2,406,244	2,002,172	4,615,148	3,894,392
Selling	607,511	335,089	1,054,963	850,121
Research and development	218,724	151,663	399,339	370,621
Total operating expenses	3,232,479	2,488,924	6,069,450	5,115,134
Loss from operations	(245,857)	(386,030)	(168,157)	(1,292,896)
Other income (expense)
Interest and other income	7,397	2,770	6,184	5,661
Interest expense	(38,082)	(44,053)	(69,784)	(86,434)
Total other expense, net	(30,685)	(41,283)	(63,600)	(80,773)
Consolidated net loss	(276,542)	(427,313)	(231,757)	(1,373,669)
(Income) loss attributable to the noncontrolling interest	(16,998)	11,774	(16,998)	64,962
Net loss attributable to Tecogen Inc.	(293,540)	(415,539)	(248,755)	(1,308,707)
Other comprehensive loss - unrealized loss on securities	(224,359)	0	(224,359)	0
Comprehensive loss	$ (517,899)	$ (415,539)	$ (473,114)	$ (1,308,707)
Net loss per share - basic and diluted (usd per share)	$ (0.01)	$ (0.02)	$ (0.01)	$ (0.07)
Weighted average shares outstanding - basic and diluted (shares)	23,120,351	19,088,828	21,587,589	18,783,909

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Cash Flows - USD ($)	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
CASH FLOWS FROM OPERATING ACTIVITIES:
Consolidated net loss	$ (231,757)	$ (1,373,669)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	242,876	131,941
Provision (recovery) of inventory reserve	25,609	(40,000)
Stock-based compensation	97,684	88,177
Non-cash interest expense	389	23,050
Loss on sale of assets	2,909	640
Provision for losses on accounts receivable	1,335	0
Changes in operating assets and liabilities, net of effects of acquisitions
Short term investments	0	294,802
Accounts receivable	355,740	(954,191)
Unbilled revenue	(952,864)	(141,827)
Inventory, net	(1,242,782)	782,728
Due from related party	(118,612)	785,818
Prepaid expenses and other current assets	(99,601)	(134,033)
Other non-current assets	65,687	0
Increase (decrease) in:
Accounts payable	786,419	(693,524)
Accrued expenses and other current liabilities	(10,362)	(30,078)
Deferred revenue	176,852	(165,186)
Interest payable, related party	8,523	0
Net cash used in operating activities	(891,955)	(1,425,352)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(209,265)	(100,925)
Purchases of intangible assets	(22,539)	(50,970)
Cash acquired in acquisition	971,454
Payment of stock issuance costs	(365,566)
Net cash provided by (used in) investing activities	374,084	(151,895)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from demand notes payable, related party	0	150,000
Payment of stock issuance costs	0	(8,544)
Proceeds from the exercise of stock options	114,034	18,925
Net cash provided by financing activities	114,034	160,381
Net decrease in cash and cash equivalents	(403,837)	(1,416,866)
Cash and cash equivalents, beginning of the period	3,721,765	5,486,526
Cash and cash equivalents, end of the period	3,317,928
Non-cash investing and financing activities:
Cash paid for interest	0	72,199
Exchange of stock for non-controlling interest in Ilios	0	330,852
Issuance of stock to acquire American DG Energy	18,745,007	0
Issuance of Tecogen stock options in exchange for American DG Energy options	$ 114,896	$ 0

Description of business and bas

Description of business and basis of presentation	6 Months Ended
	Jun. 30, 2017
Accounting Policies [Abstract]
Description of business and basis of presentation	Description of Business and Basis of Presentation Description of business Tecogen Inc., or the Company, we, our or us produces commercial and industrial, natural-gas-fueled engine-driven, combined heat and power (CHP) products that reduce energy costs, decrease greenhouse gas emissions and alleviate congestion on the national power grid. The Company’s products supply electric power or mechanical power for cooling, while heat from the engine is recovered and purposefully used at a facility. The Company also installs, owns, operates and maintains complete energy systems and other complementary systems at customer sites and sells electricity, hot water, heat and cooling energy under long-term contracts at prices guaranteed to the customer to be below conventional utility rates. The majority of the Company’s customers are located in regions with the highest utility rates, typically California, the Midwest and the Northeast. The Company's common stock is listed on the NASDAQ under the ticker symbol TGEN. On May 18, 2017, the Company acquired 100% of the outstanding common stock of American DG Energy Inc., formerly a related entity, in a stock-for-stock merger (see Note 3. "Acquisition of American DG Energy Inc."). Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles for interim financial information and with the instructions to Form 10-Q and Article 8 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements. In the opinion of management, all adjustments considered necessary for a fair presentation have been included. Operating results for the six months ended June 30, 2017 are not necessarily indicative of the results that may be expected for the year ending December 31, 2017. The condensed consolidated balance sheet at December 31, 2016 has been derived from the audited consolidated financial statements at that date but does not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements. For further information, refer to the consolidated financial statements and footnotes thereto included in Tecogen Inc.'s Annual Report on Form 10-K and American DG Energy Inc.'s Annual Report on Form 10-K for the year ended December 31, 2016. There have been no significant changes in accounting principles, practices or methods for making estimates. The accompanying unaudited condensed consolidated financial statements include the accounts of the Company and entities in which it has a controlling financial interest. Those entities include the Company's wholly-owned subsidiaries American DG Energy Inc. and Ilios Inc. and a joint venture, American DG New York, LLC, in which American DG Energy Inc. holds a 51.0% interest. Investments in partnerships and companies in which the Company does not have a controlling financial interest but where we have significant influence are accounted for under the equity method. The Company’s operations are comprised of two business segments. Our Products and Services segment designs, manufactures and sells industrial and commercial cogeneration systems as described above. Our Energy Production segment sells energy in the form of electricity, heat, hot water and cooling to our customers under long-term sales agreements. Reclassification Certain prior period amounts have been reclassified to conform with current year presentation. Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Income Taxes The provisions for income taxes in the accompanying unaudited consolidated statements of operations differ from that which would be expected by applying the federal statutory tax rate primarily due to losses for which no benefit is recognized. Significant New Accounting Standards or Updates Not Yet Effective Revenue Recognition In May 2014, the Financial Accounting Standards Board ("FASB") issued an accounting standard update related to revenue from contracts with customers, which, along with amendments issued in 2015 and 2016, will supersede nearly all current U.S. GAAP guidance on this topic and eliminate industry-specific guidance. The underlying principle is to recognize revenue when promised goods or services are transferred to customers in an amount that reflects the consideration that is expected to be received for those goods or services. This accounting standard update, as amended, will be effective for the Company beginning in the first quarter of fiscal 2018. The new revenue standard may be applied retrospectively to each prior period presented or retrospectively with the cumulative effect recognized in retained earnings as of the date of adoption ("modified retrospective basis"). The Company expects to adopt this accounting standard update on a modified retrospective basis in the first quarter of fiscal 2018, and it is currently evaluating the impact of this accounting standard update on its consolidated financial statements. Leases In February 2016, the FASB issued an accounting standard update related to leases requiring lessees to recognize operating and financing lease liabilities on the balance sheet, as well as corresponding right-of-use assets. The new lease standard also makes some changes to lessor accounting and aligns key aspects of the lessor accounting model with the revenue recognition standard. In addition, disclosures will be required to enable users of financial statements to assess the amount, timing, and uncertainty of cash flows arising from leases. The accounting standard update will be effective for the Company beginning in the first quarter of fiscal 2019 on a modified retrospective basis, and early adoption is permitted. The Company is currently evaluating the impact of this accounting standard update on its consolidated financial statements.

Loss per common share

Loss per common share	6 Months Ended
	Jun. 30, 2017
Earnings Per Share [Abstract]
Loss per common share	Loss Per Common Share Basic and diluted loss per share for the three and six months ended June 30, 2017 and 2016 , respectively, were as follows: Three months ended June 30, Six months ended June 30, 2017 2016 2017 2016 Net loss attributable to stockholders $ (293,540 ) $ (415,539 ) $ (248,755 ) $ (1,308,707 ) Weighted average shares outstanding - Basic and diluted 23,120,351 19,088,828 21,587,589 18,783,909 Basic loss per share $(0.01) $(0.02) $ (0.01 ) $ (0.07 ) Anti-dilutive shares underlying stock options outstanding 1,053,778 1,196,776 1,053,778 1,196,776 Anti-dilutive convertible debentures 889,830 889,830 889,830 889,830 Anti-dilutive warrants outstanding 250,000 1,150,000 250,000 1,150,000

Acquisition of American DG Ener

Acquisition of American DG Energy, Inc. (Notes)	6 Months Ended
	Jun. 30, 2017
Business Combinations [Abstract]
Acquisition of American DG Energy, Inc.	Acquisition of American DG Energy Inc. On May 18, 2017, we completed our acquisition, by means of a stock-for-stock merger, of 100% of the outstanding common shares of American DG Energy Inc. (“American DG Energy" or "ADGE”), a company which installs, owns, operates and maintains complete distributed generation of electricity systems, or DG systems or energy systems, and other complementary systems at customer sites and sells electricity, hot water, heat and cooling energy under long-term contracts at prices guaranteed to the customer to be below conventional utility rates, by means of a merger of one of our wholly owned subsidiaries with and into ADGE such that ADGE became a wholly owned subsidiary of Tecogen. We acquired ADGE to, among other reasons, expand our product offerings and benefit directly from the long-term contracted revenue streams generated by these installations. We gained control of ADGE on May 18, 2017 by issuing common stock to the prior stockholders of ADGE. We have included the financial results of ADGE in our condensed consolidated financial statements from the date of acquisition. For the three and six months ended June 30, 2017 , ADGE contributed $774,192 to our total revenues and $443,649 to our gross profit. Acquisition related costs included in general and administrative expenses totaled $99,773 and $118,853 , respectively for the three and six month periods ended June 30, 2017 . Stock issuance related costs totaling $365,566 were netted against additional paid in capital during the six month period ended June 30, 2017 . The merger is intended to qualify for federal income tax purposes as a tax-free reorganization under the provisions of Section 368(a) of the Internal Revenue Code of 1986. Subject to the terms and conditions of the merger agreement, at the closing of the merger, each outstanding share of ADGE common stock was converted into the right to receive approximately 0.092 shares of common stock of Tecogen (the "Exchange Ratio"). Also in connection with the merger, Tecogen, at the effective time of the merger, assumed the (a) outstanding stock options of ADGE and (b) outstanding warrants to purchase common stock of ADGE, each as adjusted pursuant to the Exchange Ratio and subject to the terms of the merger agreement. The fair value of the 4,662,937 shares of common stock issued as part of the consideration for the acquisition was determined based on the closing market price of Tecogen’s stock on the date of acquisition. Additionally, as there is no required service condition in the assumed equity-based awards, 100% of the estimated fair value of the replacement equity-based awards at the date of the merger is considered attributable to pre-combination service and accordingly is included in the consideration. The following table summarizes the consideration paid for ADGE and the amounts of the assets acquired and liabilities assumed recognized at the acquisition date, as well as the fair value at the acquisition date of the noncontrolling interest in American DG New York, LLC, a consolidated subsidiary of ADGE. Consideration Tecogen common stock - 4,662,937 shares $ 18,745,007 Assumed fully vested equity awards 114,896 $ 18,859,903 Recognized amounts of identifiable assets acquired and liabilities assumed Financial assets $ 1,583,190 Inventory 108,333 Prepaid and other current assets 358,628 Property, plant and equipment 15,430,250 Investment securities 519,568 Identifiable intangibles assets 1,456,166 Financial liabilities (1,857,859 ) Unfavorable contract liability (10,838,571 ) Other liabilities (939 ) Total identifiable net assets 6,758,766 Noncontrolling interest in American DG New York, LLC (469,672 ) Excess of cost over fair value of net assets acquired 12,570,809 $ 18,859,903 Amounts recognized in respect of inventory, property, plant and equipment, identifiable intangible assets, unfavorable contract liability and noncontrolling interest are provisional pending completion of the necessary valuations and analysis. Excess of cost over fair value of net assets acquired of $ 12.6 million arising from the acquisition is primarily attributable to the going concern element of ADGE’s business, including its assembled workforce and the long-term contractual nature of its business, as well as expected cost synergies from the merger related primarily to the elimination of administrative overhead and duplicative personnel. None of the excess purchase price over net assets acquired recognized is expected to be deductible for income tax purposes. Identified intangible assets and the unfavorable contract liability, both of which relate to existing customer contracts, and the estimated amortization are more fully described in Note 5, "Intangible Assets and Liabilities Other Than Goodwill and Excess of Cost Over Fair Value of Net Assets Acquired". The fair value of the noncontrolling interest in American DG New York, LLC, a consolidated subsidiary of ADGE, was estimated using the income approach. This fair value measurement is based on significant inputs that are not observable in the market and thus represents a fair value measurement categorized within level 3 of the fair value hierarchy described in ASC Section 820-10-35. Key assumptions include a discount rate of 5.61% and the run out of existing contracts at current levels of profitability. Unaudited Pro Forma Financial Information The unaudited pro forma financial information in the table below summarizes the combined results of operations for Tecogen and ADGE as though the companies were combined as of the beginning of fiscal 2016. The pro forma financial information for all periods presented also includes the business combination accounting effects resulting from the acquisition including amortization charges and credits from acquired intangible assets and liabilities (certain of which are preliminary), and depreciation adjustments related to fair value as though the aforementioned companies were combined as of the beginning of fiscal 2016. The pro forma financial information as presented below is for informational purposes only and is not indicative of the results of operations that would have been achieved if the acquisition had taken place at the beginning of fiscal 2016. Three months ended June 30, Six months ended June 30, 2017 2016 2017 2016 Total revenues $ 8,303,268 $ 6,972,832 $ 16,579,392 $ 13,220,810 Net loss (833,148 ) (523,538 ) (1,294,083 ) (1,993,124 ) Basic and diluted loss per share (0.04 ) (0.02 ) (0.06 ) (0.09 ) One-time acquisition-related expenses related to the merger incurred during the three-month and six-month periods ended June 30, 2017 are not included in the unaudited pro forma financial information as they are not expected to have a continuing impact on the consolidated results. The unaudited pro forma financial information does not include the revenues or results of operations of a subsidiary previously owned and consolidated by American DG Energy as that subsidiary was disposed of in 2016 prior to acquisition by Tecogen and was considered to be a discontinued operation by American DG Energy. Additionally, the unaudited pro forma financial information does not include a gain recognized on deconsolidation of that same subsidiary by American DG Energy and an amount of interest cost related to American DG Energy's long-term debt which was extinguished contemporaneously with the disposition of the subsidiary.

Property, Plant and Equipment (

Property, Plant and Equipment (Notes)	6 Months Ended
	Jun. 30, 2017
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, Plant and Equipment Property, plant and equipment at June 30, 2017 and December 31, 2016 consisted of the following: Estimated Useful June 30, 2017 December 31, 2016 Energy systems 1 - 15 years $ 12,883,503 $ — Machinery and equipment 5 - 7 years 1,121,289 1,009,893 Furniture and fixtures 5 years 103,971 141,874 Computer software 3 - 5 years 190,152 102,415 Leasehold improvements * 440,519 437,341 14,739,434 1,691,523 Less - accumulated depreciation and amortization (1,591,488 ) (1,174,380 ) 13,147,946 517,143 Construction in progress 2,577,062 — $ 15,725,008 $ 517,143 * Lesser of estimated useful life of asset or lease term Depreciation and amortization expense on property and equipment for the three and six months ended June 30, 2017 and 2016 was $289,336 and $330,808 , and $39,543 and $83,171 , respectively.

Intangible assets and liabiliti

Intangible assets and liabilities other than goodwill and excess of cost over fair value of net assets acquired	6 Months Ended
	Jun. 30, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible assets and liabilities other than goodwill and excess of cost over fair value of net assets acquired	Intangible Assets and Liabilities Other Than Goodwill and Excess of Cost Over Fair Value of Net Assets Acquired As of June 30, 2017 and December 31, 2016 the Company had the following amounts related to intangible assets and liabilities other than goodwill and excess of cost over fair value of net assets acquired: June 30, 2017 December 31, 2016 Intangible assets Cost Accumulated Amortization Total Cost Accumulated Amortization Total Product certifications $ 598,264 $ (259,667 ) $ 338,597 $ 544,651 $ (233,992 ) $ 310,659 Patents 649,081 (138,992 ) 510,089 681,155 (123,012 ) 558,143 Developed technology 240,000 (68,000 ) 172,000 240,000 (60,000 ) 180,000 Trademarks 18,165 — 18,165 17,165 — 17,165 Favorable contract asset 1,071,096 (11,463 ) 1,059,633 — — — $ 2,576,606 $ (478,122 ) $ 2,098,484 $ 1,482,971 $ (417,004 ) $ 1,065,967 Intangible liability Unfavorable contract liability $ 10,453,501 $ (149,050 ) $ 10,304,451 $ — $ — $ — The aggregate amortization expense related to intangible assets and liabilities exclusive of contract related intangibles for the six months ended June 30, 2017 and 2016 was $ 49,655 and $48,770 , respectively. The net credit to cost of sales related to the amortization of contract related intangible assets and liabilities for the six months ended June 30, 2017 and 2016 was $137,587 and $- 0 -, respectively. Contract Assets and Liabilities The favorable contract asset and unfavorable contract liability in the foregoing table represent the estimated fair value of American DG Energy's customer contracts (both positive for favorable contracts and negative for unfavorable contracts) which were acquired by the Company on May 18, 2017 (see Note 3. "Acquisition of American DG Energy Inc."). These contracts are long-term and provide customers with an alternative source of electrical power in addition to that provided by the local power utility, at rates that are lower than local utilities. This alternative electrical power is typically produced by ADGE owned, operated and maintained natural gas powered systems installed at the customers' sites, with ADGE bearing all costs of operation and maintenance. In addition to the alternative source of electrical power provided by ADGE’s systems, customers can opt to add and take advantage of the heat generated in the electrical production process in the form of hot water and/or space heating. Pricing to the customer for electrical power produced and supplied by ADGE under the contracts is under a fixed formula which requires the customer to pay for the kilowatts of electrical power provided at a fixed percentage discount to the local utility’s electric rate for that period. As a result, as utility rates for electrical power change, the amount ADGE is able to charge the customer under the contract also changes. There has been a sharp decrease in electric rates over the past several years, subsequent to the vast majority of customer contract dates, causing the billable value of the electrical power generated by ADGE’s systems to decrease, resulting in a deterioration of expected profitability. As of the date of acquisition, utility electric rates were significantly below the level anticipated at the time the fixed percentage discounts contained in the vast majority of ADGE’s customer contracts were contracted for, thus these contract terms, although they produce cash flow, were considered to be off market in the vast majority of ADGE’s customer contracts. Additionally, the demand and volume of kilowatts produced and billed for vary by contract and by period and in certain instances have been significantly below what was originally expected such that had it been known at the time the contract(s) were negotiated, it would have influenced ADGE’s determination of the level of the fixed percentage discount in those contracts. The determination of fair value requires development of an estimate of the price at which an orderly transaction to sell the asset or to transfer the liability would take place between market participants at the measurement date under current market conditions. Contracts are considered to be assets or liabilities by virtue of the rights and obligations inherent in the contract terms. Typically, contracts with terms considered to be at market are considered to have no fair value as in order to be entitled to the rights under the contract performance must occur for which a market rate of return is earned due to the at market terms. The fair value of a contract is primarily a measurement of its off market terms. The obligation to perform under a contract with terms that are unfavorable to market results in a liability to the extent its terms are off market. The resulting liability is an estimate of the price that would need to be paid to a willing market participant to assume the obligations under the contract in order for them to receive a market rate of return for their remaining performance obligation under the contract. The exact opposite holds true in instances where the terms of a contract are considered to be favorable to market. In that case an asset would exist as an estimate of the price that would be received from a willing market participant in order to be entitled to the rights under the contract. In determining the estimate of fair value of ADGE’s customer contracts, the measure of at market, and thus the baseline to measure the amount related to any of the off market terms or conditions with respect to the contracts, was considered best determined, given the nature of the services provided under the contracts, by utilizing a benchmark level of margin contribution, in this case 35% on revenue which is consistent with the average return on revenue of US investor owned public utilities. It is believed that a market participant would have utilized a similar margin in arriving at a buy price for the contract(s). Amortization of intangibles including contract related amounts is calculated using the straight line method over the remaining useful life or contract term. Aggregate future amortization over the next five years is estimated to be as follows: Year 1 $ (1,056,338 ) Year 2 (914,783 ) Year 3 (826,089 ) Year 4 (839,851 ) Year 5 (840,519 )

Goodwill and Excess Cost over F

Goodwill and Excess Cost over Fair Value of Net Assets Acquired (Notes)	6 Months Ended
	Jun. 30, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Excess of Cost over Fair Value of Net Assets Acquired	Goodwill and Excess of Cost Over Fair Value of Net Assets Acquired Changes in the carrying amount of goodwill and excess of cost over fair value of net assets acquired were as follows: Goodwill Excess of cost over fair value of net assets acquired Balance at December 31, 2016 $ 40,870 $ — Acquisitions — 12,570,809 Balance June 30, 2017 $ 40,870 $ 12,570,809 Excess of cost over fair value of net assets acquired at June 30, 2017 has not as of yet been allocated to the respective segments pending completion of the necessary analysis.

Stock-based compensation

Stock-based compensation	6 Months Ended
	Jun. 30, 2017
Equity [Abstract]
Stock-based compensation	Stock-Based Compensation Stock-Based Compensation The Company adopted the 2006 Stock Option and Incentive Plan, or the Plan, under which the Board of Directors may grant incentive or non-qualified stock options and stock grants to key employees, directors, advisors and consultants of the Company. The Plan was amended at various dates by the Board of Directors to increase the reserved shares of common stock issuable under the Plan to 3,838,750 as of June 30, 2017 , or the Amended Plan. Stock options vest based upon the terms within the individual option grants, with an acceleration of the unvested portion of such options upon a change in control event, as defined in the Amended Plan. The options are not transferable except by will or domestic relations order. The option price per share under the Amended Plan cannot be less than the fair market value of the underlying shares on the date of the grant. The number of shares remaining available for future issuance under the Amended Plan as of June 30, 2017 was 2,190,174 . Stock option activity for the six months ended June 30, 2017 was as follows: Common Stock Options Number of Options Exercise Share Weighted Price Weighted Life Aggregate Value Outstanding, December 31, 2016 1,117,918 $0.79-$5.39 $ 3.10 5.00 years $ 1,415,150 Granted 3,000 3.72 3.72 Assumed in merger 156,124 $3.15-$30.33 — 10.35 Exercised (67,140 ) $0.79-$2.00 1.70 Canceled and forfeited (3,750 ) 2.60 2.60 Outstanding, June 30, 2017 1,206,152 $0.79-$30.33 $ 4.14 4.99 years $ 712,102 Exercisable, June 30, 2017 951,402 $ 4.04 $ 712,102 Vested and expected to vest, June 30, 2017 1,167,940 $ 4.13 $ 712,102 Consolidated stock-based compensation expense for the six months ended June 30, 2017 and 2016 was $97,684 and $88,177 , respectively. No tax benefit was recognized related to the stock-based compensation recorded during the periods.

Fair Value Measurements (Notes)

Fair Value Measurements (Notes)	6 Months Ended
	Jun. 30, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The fair value topic of the FASB Accounting Standards Codification defines fair value 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 on the measurement date. The accounting guidance also establishes a fair value hierarchy which requires an entity to maximize the use of observable inputs, where available, and minimize the use of unobservable inputs when measuring fair value. There are three levels of inputs that may be used to measure fair value: Level 1 - Unadjusted quoted prices in active markets for identical assets or liabilities. The Company currently does not have any Level 1 financial assets or liabilities. Level 2 - Observable inputs other than quoted prices included in Level 1. Level 2 inputs include quoted prices for identical assets or liabilities in non-active markets, quoted prices for similar assets or liabilities in active markets and inputs other than quoted prices that are observable for substantially the full term of the asset or liability. Level 3 - Unobservable inputs reflecting management’s own assumptions about the input used in pricing the asset or liability. The following table presents the asset reported in the consolidated balance sheet measured at its fair value on a recurring basis as of June 30, 2017 by level within the fair value hierarchy. June 30, 2017 Quoted prices in active markets for identical assets Significant other observable inputs Significant unobservable inputs Total Level 1 Level 2 Level 3 Total gains (losses) Recurring fair value measurements Available-for-sale equity securities EuroSite Power Inc. $ 295,209 $ — $ — $ 295,209 $ (224,359 ) Total recurring fair value measurements $ 295,209 $ — $ — $ 295,209 $ (224,359 ) The Company utilizes a Level 3 category fair value measurement to value its investment in EuroSite Power as an available-for-sale security at period end. That measurement is determined by management based on the lowest closing sales price in a 15 day trading period prior to period end. The following table summarizes changes in level 3 assets which are comprised of available-for-sale securities for the period: Fair value at acquisition on May 18, 2017 $ 519,568 Unrealized loss recognized in other comprehensive loss (224,359 ) Fair value at June 30, 2017 $ 295,209

Commitments and contingencies

Commitments and contingencies	6 Months Ended
	Jun. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and contingencies	Commitments and Contingencies The Company guarantees certain obligations of a former subsidiary of American DG Energy, EuroSite Power Inc. These guarantees include a payment performance guarantee in respect of collateralized equipment financing loans, with a remaining principal amount outstanding subject to the guarantee at June 30, 2017 of approximately $310,000 due ratably in equal installments through September 2021, and certain guarantees of performance in respect of certain customer contracts. Based on current conditions, the Company does not believe there to be any amounts probable of payment by the Company under any of the guarantees and has estimated the value associated with the non-contingent aspect of the guarantees is approximately $10,000 which is recorded as liability in the accompanying financial statements. Legal Proceedings Tecogen is not currently a party to any material litigation arising from its operations, and it is not aware of any pending or threatened litigation against it relating to its operations that could have a material adverse effect on its business, operating results or financial condition. However, it is or has been a party to a claim in the Superior Court of the Commonwealth of Massachusetts and named as a defendant in a case in the United States District Court for the District of Massachusetts, described below, related to the Merger. Massachusetts Superior Court Action On or about February 6, 2017, ADGE, John Hatsopoulos, George N. Hatsopoulos, Charles T. Maxwell, Deanna M. Petersen, Christine Klaskin, John Rowe, Joan Giacinti, Elias Samaras, Tecogen, and Merger Sub were served with a Verified Complaint by William C. May ("May"), individually and on behalf of the other shareholders of ADGE as a class. The action was commenced in the Business Litigation Session of the Superior Court of the Commonwealth of Massachusetts, Civil Action No. 17-0390. The complaint alleged class action claims arising out of the proposed Merger. On May 31, 2017, May voluntarily dismissed the action and consolidated his claims with the pending federal action in the United States District Court for the District of Massachusetts. If the complaint in the federal court is dismissed, it is possible that May or another plaintiff will recommence an action in state court with similar claims to those asserted by May. United States District Court Action On or about February 15, 2017, a lawsuit was filed in the United States District Court for the District of Massachusetts by Lee Vardakas (“Vardakas”), individually and on behalf of other stockholders of ADGE, naming ADGE, John N. Hatsopoulos, George N. Hatsopoulos, Benjamin Locke, Charles T. Maxwell, Deanne M. Petersen, Christine M. Klaskin, John Rowe, Joan Giacinti, Elias Samaras, Tecogen., Merger Sub., and Cassel Salpeter and Co., LLC, as defendants. The action is captioned Vardakas v. American DG Energy, Inc. , Case No. 17-CV-10247(LTS). At the time Vardakas commenced the action, his complaint challenged the proposed Merger between Tecogen and ADGE. On May 18, 2017, ADGE’s and Tecogen’s shareholders approved the Merger. Following the consummation of the Merger (and the appointment of May, from the Massachusetts Superior Court Action, as lead plaintiff), Vardakas filed an Amended Class Action Complaint (the “Amended Complaint”). The Amended Complaint discontinued the claims against Cassel Salpeter & Co., LLC but asserted against the remaining defendants claims under Section 14(a) of the Securities Exchange Act of 1934 (the “Exchange Act”) and SEC Rule 14a-9; claims against certain defendants for control person liability under § 20(a) of the Exchange Act (collectively, the “Federal Securities Law Claims”); and common law claims for breach of fiduciary duty and aiding and abetting (the “State Law Claims”). The Federal Securities Law Claims allege, in substance, that defendants made material nondisclosure in the proxy statement about the process leading to the merger and about the fairness opinion relied upon by ADGE’s Board of Directors in recommending the Merger to shareholders. The State Law Claims assert, in substance, that defendants breached their fiduciary duties in negotiating and approving the merger, which, plaintiff claims, deprived ADGE’s nonaffiliated shareholders of fair value for their shares. On July 19, 2017, defendants moved to dismiss the Amended Complaint. In their motion papers, defendants contend that the Federal Securities Law Claims are not sufficiently pleaded and fail to state a viable claim. Defendants also assert that if the Federal Securities Law Claims are dismissed, the district court must also dismiss the State Law Claims because it would lack subject matter jurisdiction. Plaintiff’s deadline to respond to the motion is August 18, 2017 and defendants will file a reply brief on September 8, 2017. The Company believes that the lawsuit is without merit and intends to defend vigorously. The Amended Complaint does not specify the amount of damages claimed and any estimate by the Company would be unduly speculative.

Related party transactions

Related party transactions	6 Months Ended
	Jun. 30, 2017
Related Party Transactions [Abstract]
Related party transactions	Related Party Transactions The Company has two affiliated companies, namely Ultra Emissions Technologies Ltd, and TTcogen LLC. These companies are related because either several of the major stockholders of those companies, have a significant ownership position in the Company or they are joint ventures between Tecogen and other parties. In January of 2017, prior to its acquisition of American DG Energy, the Company purchased a large quantity of used equipment from American DG Energy for approximately $985,000 . Tecogen plans to sell this equipment to specific customers in the coming quarters. In connection with the acquisition of American DG Energy, the Company assumed a loan from John N. Hatsopoulos, the Company's Co-Chief Executive Officer and a Company Director. The loan is in the amount of $850,000 and bears interest at 6% , payable quarterly, and matures and becomes due and payable on May 25, 2018. Ultra Emissions Technologies Ltd. On December 28, 2015, the Company entered into a joint venture agreement relating to the formation of a joint venture company (the “JV”) organized to develop and commercialize Tecogen’s patented technology (“Ultera ® Technology”) designed to reduce harmful emissions generated by engines using fossil fuels. The joint venture company, called Ultra Emissions Technologies Limited, was organized under the laws of the Island of Jersey, Channel Islands. The Company received a 50% equity interest in the JV in exchange for a fully paid-up worldwide license to use Tecogen’s Ultera emissions control technology in the field of mobile vehicles burning fossil fuels. The other half of the joint venture equity interests were purchased for $3,000,000 by a small group of offshore investors. Warrants to purchase additional equity securities in the JV were granted to all parties pro rata. If the venture is not successful, all licensed intellectual property rights will revert to Tecogen. On August 2, 2016, Tecogen exercised 2,000,000 warrants (the "Ultratek Warrants"), in the JV, at $1.00 per share, for an aggregate amount of $2 million . The funds used to exercise the Ultratek Warrants were acquired by the Company from the holders of certain Company warrants (the "Tecogen Warrant Holders"), when they partially exercised their Tecogen warrants (the "Tecogen Warrants"), in July of 2016. The Tecogen Warrant Holders exercised a total of 675,000 Tecogen Warrants with a $4.00 exercise price, resulting in cash proceeds of $2,700,000 to the Company, which the Company then used in part to invest in the JV. An additional $8,500,000 was raised from other outside investors for a total equity investment in the JV to date of $13,500,000 . Due to this investment, Tecogen's ownership has decreased to 43% . The JV is expected to have losses as it performs the necessary research and development with the Ultera technology. The Company accounts for its interest in the JV using the equity method. Income and losses will be recorded consistent with an agreement between the JV shareholders as to how income and losses will be allocated. These allocations are consistent with the allocation of cash distributions and liquidating distributions of the JV. The shareholder agreement calls for Tecogen's investment to be returned before any other shareholder if the venture does not achieve commercialization. As a result, as of June 30, 2017, Tecogen has not recorded any of the losses of the JV as the cumulative losses of the JV have not exceeded the other owners' investments to date. As of June 30, 2017 , $94,407 is due to Tecogen from Ultratek. TTcogen LLC On May 19, 2016, the Company along with Tedom a.s., a corporation incorporated in the Czech Republic and a European combined heat and power product manufacture ("Tedom"), entered into a joint venture, where the Company will hold a 50% participating interest and the remaining 50% interest will be with Tedom. As part of the joint venture, the parties agreed to create a Delaware limited liability company, TTcogen LLC ("TTcogen"), to carry out the business of the venture. Tedom granted TTcogen the sole and exclusive right to market, sell, offer for sale, and distribute certain products as agreed to by the parties throughout the United States. The product offerings of the joint venture expand the current Tecogen product offerings to the MicroCHP of 35kW to large 4,000kW plants. Tecogen agreed to refer all appropriate sale leads to TTcogen regarding the products agreed to by the parties and Tecogen shall have the first right to repair and maintain the products sold by TTcogen. The Company accounts for its interest in TTcogen's operations using equity method accounting. Any initial operating losses of TTcogen are to be borne and funded by Tedom. To the extent any such losses are borne and funded solely by Tedom, the Company will not recognize any portion of such losses given the Company does not guarantee the obligations of the joint venture nor is it committed to provide funding to the joint venture. As of period ending June 30, 2017 , $279,069 is due to Tecogen from TTcogen.

Segments (Notes)

Segments (Notes)	6 Months Ended
	Jun. 30, 2017
Segment Reporting [Abstract]
Segments	Segments As of June 30, 2017, the Company was organized into two operating divisions through which senior management evaluates the Company’s business. These divisions, as described in more detail in Note 1, are organized around the products and services provided to customers and represent the Company’s reportable segments. Prior to the acquisition of ADGE (see Note 3. “Acquisition of American DG Energy Inc.”), the Company’s operations were comprised of a single segment. The following table presents information by reportable segment for the three month periods ended June 30, 2017 and 2016 and the six month periods ended June 30, 2017 and 2016: Products and Services Energy Production Corporate, other and elimination (1) Total Three months ended June 30, 2017 Revenue - external customers $ 6,816,348 $ 774,192 $ — $ 7,590,540 Intersegment revenue 191,818 — (191,818 ) — Total revenue 7,008,166 774,192 (191,818 ) 7,590,540 Gross profit 2,542,973 443,649 — 2,986,622 Identifiable assets 17,687,401 16,288,369 21,610,279 55,586,049 Three months ended June 30, 2016 Revenue - external customers $ 5,687,308 $ — $ — $ 5,687,308 Intersegment revenue — — — — Total revenue 5,687,308 — — 5,687,308 Gross profit 2,102,894 — — 2,102,894 Identifiable assets 17,524,410 — 6,216,951 23,741,361 Six months ended June 30, 2017 Revenue - external customers $ 13,663,113 $ 774,192 $ — $ 14,437,305 Intersegment revenue 191,818 — (191,818 ) — Total revenue 13,854,931 774,192 (191,818 ) 14,437,305 Gross profit 5,457,644 443,649 — 5,901,293 Identifiable assets 17,687,401 16,288,369 21,610,279 55,586,049 Six months ended June 30, 2016 Revenue - external customers $ 10,762,823 $ — $ — $ 10,762,823 Intersegment revenue — — — — Total revenue 10,762,823 — — 10,762,823 Gross profit 3,822,238 — — 3,822,238 Identifiable assets 17,524,410 — 6,216,951 23,741,361 (1) Corporate, intersegment revenue, other and elimination includes various corporate assets. Excess of cost over fair value of net assets acquired at June 30, 2017 has not as of yet been allocated to the respective segments pending completion of the necessary analysis.

Subsequent Events

Subsequent Events	6 Months Ended
	Jun. 30, 2017
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events The Company has evaluated subsequent events through the date of this filing and determined that no subsequent events occurred that would require recognition in the consolidated financial statements or disclosure in the notes thereto.

Description of business and b18

Description of business and basis of presentation (Policies)	6 Months Ended
	Jun. 30, 2017
Accounting Policies [Abstract]
Principles of Consolidation and Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles for interim financial information and with the instructions to Form 10-Q and Article 8 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements. In the opinion of management, all adjustments considered necessary for a fair presentation have been included. Operating results for the six months ended June 30, 2017 are not necessarily indicative of the results that may be expected for the year ending December 31, 2017. The condensed consolidated balance sheet at December 31, 2016 has been derived from the audited consolidated financial statements at that date but does not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements. For further information, refer to the consolidated financial statements and footnotes thereto included in Tecogen Inc.'s Annual Report on Form 10-K and American DG Energy Inc.'s Annual Report on Form 10-K for the year ended December 31, 2016. There have been no significant changes in accounting principles, practices or methods for making estimates. The accompanying unaudited condensed consolidated financial statements include the accounts of the Company and entities in which it has a controlling financial interest. Those entities include the Company's wholly-owned subsidiaries American DG Energy Inc. and Ilios Inc. and a joint venture, American DG New York, LLC, in which American DG Energy Inc. holds a 51.0% interest. Investments in partnerships and companies in which the Company does not have a controlling financial interest but where we have significant influence are accounted for under the equity method. The Company’s operations are comprised of two business segments. Our Products and Services segment designs, manufactures and sells industrial and commercial cogeneration systems as described above. Our Energy Production segment sells energy in the form of electricity, heat, hot water and cooling to our customers under long-term sales agreements.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates
Income Taxes	Income Taxes The provisions for income taxes in the accompanying unaudited consolidated statements of operations differ from that which would be expected by applying the federal statutory tax rate primarily due to losses for which no benefit is recognized.

Loss per common share (Tables)

Loss per common share (Tables)	6 Months Ended
	Jun. 30, 2017
Earnings Per Share [Abstract]
Schedule of Income (Loss) Per Common Share, Basic and Diluted	Basic and diluted loss per share for the three and six months ended June 30, 2017 and 2016 , respectively, were as follows: Three months ended June 30, Six months ended June 30, 2017 2016 2017 2016 Net loss attributable to stockholders $ (293,540 ) $ (415,539 ) $ (248,755 ) $ (1,308,707 ) Weighted average shares outstanding - Basic and diluted 23,120,351 19,088,828 21,587,589 18,783,909 Basic loss per share $(0.01) $(0.02) $ (0.01 ) $ (0.07 ) Anti-dilutive shares underlying stock options outstanding 1,053,778 1,196,776 1,053,778 1,196,776 Anti-dilutive convertible debentures 889,830 889,830 889,830 889,830 Anti-dilutive warrants outstanding 250,000 1,150,000 250,000 1,150,000

Acquisition of American DG En20

Acquisition of American DG Energy, Inc. (Tables)	6 Months Ended
	Jun. 30, 2017
Business Combinations [Abstract]
Schedule of Business Acquisition	The following table summarizes the consideration paid for ADGE and the amounts of the assets acquired and liabilities assumed recognized at the acquisition date, as well as the fair value at the acquisition date of the noncontrolling interest in American DG New York, LLC, a consolidated subsidiary of ADGE. Consideration Tecogen common stock - 4,662,937 shares $ 18,745,007 Assumed fully vested equity awards 114,896 $ 18,859,903 Recognized amounts of identifiable assets acquired and liabilities assumed Financial assets $ 1,583,190 Inventory 108,333 Prepaid and other current assets 358,628 Property, plant and equipment 15,430,250 Investment securities 519,568 Identifiable intangibles assets 1,456,166 Financial liabilities (1,857,859 ) Unfavorable contract liability (10,838,571 ) Other liabilities (939 ) Total identifiable net assets 6,758,766 Noncontrolling interest in American DG New York, LLC (469,672 ) Excess of cost over fair value of net assets acquired 12,570,809 $ 18,859,903
Pro Forma Information	The unaudited pro forma financial information in the table below summarizes the combined results of operations for Tecogen and ADGE as though the companies were combined as of the beginning of fiscal 2016. The pro forma financial information for all periods presented also includes the business combination accounting effects resulting from the acquisition including amortization charges and credits from acquired intangible assets and liabilities (certain of which are preliminary), and depreciation adjustments related to fair value as though the aforementioned companies were combined as of the beginning of fiscal 2016. The pro forma financial information as presented below is for informational purposes only and is not indicative of the results of operations that would have been achieved if the acquisition had taken place at the beginning of fiscal 2016. Three months ended June 30, Six months ended June 30, 2017 2016 2017 2016 Total revenues $ 8,303,268 $ 6,972,832 $ 16,579,392 $ 13,220,810 Net loss (833,148 ) (523,538 ) (1,294,083 ) (1,993,124 ) Basic and diluted loss per share (0.04 ) (0.02 ) (0.06 ) (0.09 )

Property, Plant and Equipment21

Property, Plant and Equipment (Tables)	6 Months Ended
	Jun. 30, 2017
Property, Plant and Equipment [Abstract]
Summary of Property, Plant and Equipment	Property, plant and equipment at June 30, 2017 and December 31, 2016 consisted of the following: Estimated Useful June 30, 2017 December 31, 2016 Energy systems 1 - 15 years $ 12,883,503 $ — Machinery and equipment 5 - 7 years 1,121,289 1,009,893 Furniture and fixtures 5 years 103,971 141,874 Computer software 3 - 5 years 190,152 102,415 Leasehold improvements * 440,519 437,341 14,739,434 1,691,523 Less - accumulated depreciation and amortization (1,591,488 ) (1,174,380 ) 13,147,946 517,143 Construction in progress 2,577,062 — $ 15,725,008 $ 517,143 * Lesser of estimated useful life of asset or lease term

Intangible assets and liabili22

Intangible assets and liabilities other than goodwill and excess of cost over fair value of net assets acquired (Tables)	6 Months Ended
	Jun. 30, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Intangible Assets	As of June 30, 2017 and December 31, 2016 the Company had the following amounts related to intangible assets and liabilities other than goodwill and excess of cost over fair value of net assets acquired: June 30, 2017 December 31, 2016 Intangible assets Cost Accumulated Amortization Total Cost Accumulated Amortization Total Product certifications $ 598,264 $ (259,667 ) $ 338,597 $ 544,651 $ (233,992 ) $ 310,659 Patents 649,081 (138,992 ) 510,089 681,155 (123,012 ) 558,143 Developed technology 240,000 (68,000 ) 172,000 240,000 (60,000 ) 180,000 Trademarks 18,165 — 18,165 17,165 — 17,165 Favorable contract asset 1,071,096 (11,463 ) 1,059,633 — — — $ 2,576,606 $ (478,122 ) $ 2,098,484 $ 1,482,971 $ (417,004 ) $ 1,065,967 Intangible liability Unfavorable contract liability $ 10,453,501 $ (149,050 ) $ 10,304,451 $ — $ — $ —
Schedule of Future Amortization Expense	Aggregate future amortization over the next five years is estimated to be as follows: Year 1 $ (1,056,338 ) Year 2 (914,783 ) Year 3 (826,089 ) Year 4 (839,851 ) Year 5 (840,519 )

Goodwill and Excess Cost over23

Goodwill and Excess Cost over Fair Value of Net Assets Acquired (Tables)	6 Months Ended
	Jun. 30, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill and Excess of Cost over Fair Value of Net Assets Acquired	Changes in the carrying amount of goodwill and excess of cost over fair value of net assets acquired were as follows: Goodwill Excess of cost over fair value of net assets acquired Balance at December 31, 2016 $ 40,870 $ — Acquisitions — 12,570,809 Balance June 30, 2017 $ 40,870 $ 12,570,809

Stock-based compensation (Table

Stock-based compensation (Tables)	6 Months Ended
	Jun. 30, 2017
Tecogen
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of Stock Option Activity	Stock option activity for the six months ended June 30, 2017 was as follows: Common Stock Options Number of Options Exercise Share Weighted Price Weighted Life Aggregate Value Outstanding, December 31, 2016 1,117,918 $0.79-$5.39 $ 3.10 5.00 years $ 1,415,150 Granted 3,000 3.72 3.72 Assumed in merger 156,124 $3.15-$30.33 — 10.35 Exercised (67,140 ) $0.79-$2.00 1.70 Canceled and forfeited (3,750 ) 2.60 2.60 Outstanding, June 30, 2017 1,206,152 $0.79-$30.33 $ 4.14 4.99 years $ 712,102 Exercisable, June 30, 2017 951,402 $ 4.04 $ 712,102 Vested and expected to vest, June 30, 2017 1,167,940 $ 4.13 $ 712,102

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2017
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The following table presents the asset reported in the consolidated balance sheet measured at its fair value on a recurring basis as of June 30, 2017 by level within the fair value hierarchy. June 30, 2017 Quoted prices in active markets for identical assets Significant other observable inputs Significant unobservable inputs Total Level 1 Level 2 Level 3 Total gains (losses) Recurring fair value measurements Available-for-sale equity securities EuroSite Power Inc. $ 295,209 $ — $ — $ 295,209 $ (224,359 ) Total recurring fair value measurements $ 295,209 $ — $ — $ 295,209 $ (224,359 )
Fair Value of Investments	The following table summarizes changes in level 3 assets which are comprised of available-for-sale securities for the period: Fair value at acquisition on May 18, 2017 $ 519,568 Unrealized loss recognized in other comprehensive loss (224,359 ) Fair value at June 30, 2017 $ 295,209

Segments (Tables)

Segments (Tables)	6 Months Ended
	Jun. 30, 2017
Segment Reporting [Abstract]
Schedule of Segment Reporting Information	The following table presents information by reportable segment for the three month periods ended June 30, 2017 and 2016 and the six month periods ended June 30, 2017 and 2016: Products and Services Energy Production Corporate, other and elimination (1) Total Three months ended June 30, 2017 Revenue - external customers $ 6,816,348 $ 774,192 $ — $ 7,590,540 Intersegment revenue 191,818 — (191,818 ) — Total revenue 7,008,166 774,192 (191,818 ) 7,590,540 Gross profit 2,542,973 443,649 — 2,986,622 Identifiable assets 17,687,401 16,288,369 21,610,279 55,586,049 Three months ended June 30, 2016 Revenue - external customers $ 5,687,308 $ — $ — $ 5,687,308 Intersegment revenue — — — — Total revenue 5,687,308 — — 5,687,308 Gross profit 2,102,894 — — 2,102,894 Identifiable assets 17,524,410 — 6,216,951 23,741,361 Six months ended June 30, 2017 Revenue - external customers $ 13,663,113 $ 774,192 $ — $ 14,437,305 Intersegment revenue 191,818 — (191,818 ) — Total revenue 13,854,931 774,192 (191,818 ) 14,437,305 Gross profit 5,457,644 443,649 — 5,901,293 Identifiable assets 17,687,401 16,288,369 21,610,279 55,586,049 Six months ended June 30, 2016 Revenue - external customers $ 10,762,823 $ — $ — $ 10,762,823 Intersegment revenue — — — — Total revenue 10,762,823 — — 10,762,823 Gross profit 3,822,238 — — 3,822,238 Identifiable assets 17,524,410 — 6,216,951 23,741,361 (1) Corporate, intersegment revenue, other and elimination includes various corporate assets. Excess of cost over fair value of net assets acquired at June 30, 2017 has not as of yet been allocated to the respective segments pending completion of the necessary analysis.

Description of business and b27

Description of business and basis of presentation - Additional Information (Details)	May 18, 2017	Jun. 30, 2017
Business Acquisition [Line Items]
Ownerhsip interest in American DG New York, LLC (percent)		51.00%
American DG Energy, Inc.
Business Acquisition [Line Items]
Ownership interest (percent)	100.00%

Loss per common share - Schedul

Loss per common share - Schedule of Income (Loss) Per Common Share, Basic and Diluted (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Earnings Per Share [Abstract]
Net loss attributable to stockholders	$ (293,540)	$ (415,539)	$ (248,755)	$ (1,308,707)
Weighted average shares outstanding - basic and diluted (shares)	23,120,351	19,088,828	21,587,589	18,783,909
Basic and diluted loss per share (usd per share)	$ (0.01)	$ (0.02)	$ (0.01)	$ (0.07)
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (shares)	1,053,778	1,196,776	1,053,778	1,196,776
Convertible Debenture
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (shares)	889,830	889,830	889,830	889,830
Warrant
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (shares)	250,000	1,150,000	250,000	1,150,000

Acquisition of American DG En29

Acquisition of American DG Energy, Inc. - Additional information (Details)	May 18, 2017shares	Jun. 30, 2017USD ($)	Jun. 30, 2016USD ($)	Sep. 30, 2015USD ($)	Jun. 30, 2017USD ($)	Jun. 30, 2016USD ($)
Business Acquisition [Line Items]
Excess of Cost over Fair Value of Net Assets Acquired					$ 0
Energy production revenue		$ 774,192	$ 0		774,192	$ 0
Gross profit		2,986,622	$ 2,102,894		5,901,293	$ 3,822,238
Payment of stock issuance costs				$ 0	(365,566)
Shares issued in acquisition (shares) | shares	4,662,937
Discount rate used to calculate fair value of noncontrolling interest (percent)	5.61%
General and Administrative Expense
Business Acquisition [Line Items]
Acquisition related costs		99,773			118,853
American DG Energy, Inc.
Business Acquisition [Line Items]
Ownership interest (percent)	100.00%
Energy production revenue		1,047,882
Gross profit		$ 469,075			$ 443,649
Common Stock [Member]
Business Acquisition [Line Items]
Conversion ratio of American DG shares to Tecogen shares	0.092

Acquisition of American DG En30

Acquisition of American DG Energy, Inc. - Consideration, and Assets and Liabilities Assumed (Details) - USD ($)	May 18, 2017	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Business Acquisition [Line Items]
Tecogen common stock - 4,662,937 shares		$ 18,745,007	$ 0
Assumed fully vested equity awards		114,896	$ 0
Recognized amounts of identifiable assets acquired and liabilities assumed
Financial liabilities		(10,304,451)		$ 0
Noncontrolling interest		486,670		0
Excess of cost over fair value of net assets acquired		$ 12,570,809		$ 0
American DG Energy, Inc.
Business Acquisition [Line Items]
Tecogen common stock - 4,662,937 shares	$ 18,745,007
Assumed fully vested equity awards	114,896
Equity consideration	18,859,903
Recognized amounts of identifiable assets acquired and liabilities assumed
Financial assets	1,583,190
Inventory	108,333
Prepaid and other current assets	358,628
Property, plant and equipment	15,430,250
Investment securities	519,568
Identifiable intangibles assets	1,456,166
Financial liabilities	(1,857,859)
Unfavorable contract liability	(10,838,571)
Other liabilities	(939)
Total identifiable net assets	6,758,766
Noncontrolling interest	(469,672)
Excess of cost over fair value of net assets acquired	12,570,809
Consideration transferred	$ 18,859,903

Acquisition of American DG En31

Acquisition of American DG Energy, Inc. - Pro Forma Information (Details) - American DG Energy, Inc. - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Business Acquisition [Line Items]
Total revenues	$ 8,303,268	$ 6,972,832	$ 16,579,392	$ 13,220,810
Net loss	$ (833,148)	$ (523,538)	$ (1,294,083)	$ (1,993,124)
Basic and diluted loss per share (usd per share)	$ (0.04)	$ (0.02)	$ (0.06)	$ (0.09)

Property, Plant and Equipment -

Property, Plant and Equipment - Summary of Property and Equipment (Details) - USD ($)	6 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 14,739,434	$ 1,691,523
Less - accumulated depreciation and amortization	(1,591,488)	(1,174,380)
Property and equipment, net, before construction in progress	13,147,946	517,143
Construction in progress	2,577,062	0
Property and equipment, net	15,725,008	517,143
Energy systems
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 12,883,503	0
Energy systems | Minimum
Property, Plant and Equipment [Line Items]
Useful life - years	1 year
Energy systems | Maximum
Property, Plant and Equipment [Line Items]
Useful life - years	15 years
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 1,121,289	1,009,893
Machinery and equipment | Minimum
Property, Plant and Equipment [Line Items]
Useful life - years	5 years
Machinery and equipment | Maximum
Property, Plant and Equipment [Line Items]
Useful life - years	7 years
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 103,971	141,874
Useful life - years	5 years
Computer software
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 190,152	102,415
Computer software | Minimum
Property, Plant and Equipment [Line Items]
Useful life - years	3 years
Computer software | Maximum
Property, Plant and Equipment [Line Items]
Useful life - years	5 years
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 440,519	$ 437,341

Property, Plant and Equipment33

Property, Plant and Equipment - Depreciation (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Property, Plant and Equipment [Abstract]
Depreciation and amortization expense	$ 289,336	$ 39,543	$ 330,808	$ 83,171

Intangible assets and liabili34

Intangible assets and liabilities other than goodwill and excess of cost over fair value of net assets acquired (Details) - USD ($)	May 18, 2017	Jun. 30, 2017	Jun. 30, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization of intangible assets		$ 49,655	$ 48,770
Net credit to cost of sales for amortization of contract related intangible assets and liabilities		$ 137,587	$ 0
Benchmark level of margin contribution for measurement of fair value of customer contracts (percent)	35.00%

Intangible assets and liabili35

Intangible assets and liabilities other than goodwill and excess of cost over fair value of net assets acquired -Amounts related to intangible assets (Details) - USD ($)	Jun. 30, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Intangible assets	$ 2,576,606	$ 1,482,971
Less - accumulated amortization	(478,122)	(417,004)
Intangible assets, net	2,098,484	1,065,967
Unfavorable contract liability	10,453,501	0
Less - accumulated amortization	(149,050)	0
Unfavorable contract liability, net	10,304,451	0
Product Certifications
Finite-Lived Intangible Assets [Line Items]
Intangible assets	598,264	544,651
Less - accumulated amortization	(259,667)	(233,992)
Intangible assets, net	338,597	310,659
Patents
Finite-Lived Intangible Assets [Line Items]
Intangible assets	649,081	681,155
Less - accumulated amortization	(138,992)	(123,012)
Intangible assets, net	510,089	558,143
Developed Technology
Finite-Lived Intangible Assets [Line Items]
Intangible assets	240,000	240,000
Less - accumulated amortization	(68,000)	(60,000)
Intangible assets, net	172,000	180,000
Favorable contract asset
Finite-Lived Intangible Assets [Line Items]
Intangible assets	1,071,096	0
Less - accumulated amortization	(11,463)	0
Intangible assets, net	1,059,633	0
Trademarks
Finite-Lived Intangible Assets [Line Items]
Intangible assets	18,165	17,165
Less - accumulated amortization	0	0
Intangible assets, net	$ 18,165	$ 17,165

Intangible assets and liabili36

Intangible assets and liabilities other than goodwill and excess of cost over fair value of net assets acquired - Future Amortization of Customer Contracts (Details) - Customer Contracts	Jun. 30, 2017USD ($)
Finite-Lived Intangible Assets [Line Items]
Year 1	$ (1,056,338)
Year 2	(914,783)
Year 3	(826,089)
Year 4	(839,851)
Year 5	$ (840,519)

Goodwill and Excess Cost over37

Goodwill and Excess Cost over Fair Value of Net Assets Acquired (Details) - USD ($)	6 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Goodwill [Roll Forward]
Goodwill, beginning	$ 40,870
Acquisitions	0
Goodwill, ending	40,870
Excess of cost over fair value of net assets acquired	12,570,809	$ 0
Acquisitions	12,570,809
Excess of Cost over Fair Value of Net Assets Acquired	$ 12,570,809

Stock-based compensation - Stoc

Stock-based compensation - Stock-Based Compensation (Details) - USD ($)	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation	$ 97,684	$ 88,177
Tecogen | Amended Plan | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock reserved for future issuance	3,838,750
Number of shares remaining available for future issuance	2,190,174

Stock-based compensation - St39

Stock-based compensation - Stock Option Activity (Details) - Tecogen - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Stock Options Outstanding [Roll Forward]
Beginning (shares)	1,117,918
Granted (shares)	3,000
Assumed in merger (shares)	156,124
Exercised (shares)	(67,140)
Canceled and forfeited (shares)	(3,750)
Ending (shares)	1,206,152	1,117,918
Exercisable (shares)	951,402
Vested and expected to vest (shares)	1,167,940
Exercise Price Per Share [Abstract]
Exercise Price Per Share, Outstanding, Minimum (per share)	$ 0.79	$ 0.79
Exercise Price Per Share, Outstanding, Maximum (dollars per share)	30.33	5.39
Exercise Price Per Share, Granted (dollars per share)	3.72
Exercise Price, Canceled and Forfeited (dollars per share)	2.60
Weighted Average Exercise Price [Roll Forward]
Beginning (usd per share)	3.10
Granted (usd per share)	3.72
Assumed in merger (usd per share)	10.35
Exercised (usd per share)	1.70
Canceled and forfeited (usd per share)	2.60
Ending (usd per share)	4.14	$ 3.10
Exercisable (usd per share)	4.04
Vested and expected to vest (usd per share)	$ 4.13
Weighted Average Remaining Life	4 years 11 months 27 days	5 years
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
Outstanding, Aggregate Intrinsic Value	$ 712,102	$ 1,415,150
Exercisable, Aggregate Intrinsic Value	712,102
Vested and expected to vest, Aggregate Intrinsic Value	$ 712,102
Minimum
Exercise Price Per Share [Abstract]
Exercise Price, Assumed in Merger (dollars per share)	$ 3.15
Exercise Price Per Share, Exercised (dollars per share)	0.79
Maximum
Exercise Price Per Share [Abstract]
Exercise Price, Assumed in Merger (dollars per share)	30.33
Exercise Price Per Share, Exercised (dollars per share)	$ 2

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value on a Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($)	1 Months Ended
	Jun. 30, 2017	May 18, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total gains (losses)	$ (224,359)
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total recurring fair value measurements	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total recurring fair value measurements	0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total recurring fair value measurements	295,209
Estimate of Fair Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total recurring fair value measurements	295,209
Eurosite Power Inc
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total gains (losses)	(224,359)
Eurosite Power Inc | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale equity securities	0
Eurosite Power Inc | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale equity securities	0
Eurosite Power Inc | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale equity securities	295,209	$ 519,568
Eurosite Power Inc | Estimate of Fair Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale equity securities	$ 295,209

Fair Value Measurements - Chang

Fair Value Measurements - Change in Level 3 Assets (Details) - Fair Value, Measurements, Recurring	1 Months Ended	6 Months Ended
	Jun. 30, 2017USD ($)	Jun. 30, 2017USD ($)trading_day
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value at June 30, 2017	$ (224,359)
Eurosite Power Inc
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value at June 30, 2017	(224,359)
Eurosite Power Inc | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of trading days included in fair value measurement | trading_day		15
Unrealized loss recognized in other comprehensive loss	$ 295,209	$ 295,209

Commitments and contingencies C

Commitments and contingencies Commitments and Contingencies (Details)	Jun. 30, 2017USD ($)
Commitments and Contingencies Disclosure [Abstract]
Guarantee of obligations of Eurosite Power, Inc.	$ 310,000
Guarantee liability	$ 10,000

Related party transactions (Det

Related party transactions (Details)	Aug. 02, 2016USD ($)$ / sharesshares	Jan. 31, 2017USD ($)	Jul. 31, 2016USD ($)$ / sharesshares	Jun. 30, 2017USD ($)company	May 19, 2016	Dec. 28, 2015USD ($)
Schedule of Equity Method Investments [Line Items]
Number of affiliated companies | company				2
Equity interest in joint venture (percent)				43.00%
Warrant exercise price (per share) | $ / shares			$ 4
Proceeds from the exercise of warrants			$ 2,700,000
Investments in joint venture				$ 13,500,000
Ultra Emissions Technology Ltd.
Schedule of Equity Method Investments [Line Items]
Equity interest in joint venture (percent)						50.00%
Warrants exercised for investment in joint venture	$ 2,000,000
Due from affiliate				94,407
TTcogen, LLC
Schedule of Equity Method Investments [Line Items]
Equity interest in joint venture (percent)					50.00%
Due from affiliate				279,069
Offshore Investors
Schedule of Equity Method Investments [Line Items]
Investment by other party to joint venture						$ 3,000,000
Tedom a.s.
Schedule of Equity Method Investments [Line Items]
Equity interest in joint venture (percent)					50.00%
Warrant
Schedule of Equity Method Investments [Line Items]
Warrants exercised (shares) | shares			675,000
Warrant | Ultra Emissions Technology Ltd.
Schedule of Equity Method Investments [Line Items]
Warrants exercised (shares) | shares	2,000,000
Warrant exercise price (per share) | $ / shares	$ 1
American DG Energy
Schedule of Equity Method Investments [Line Items]
Equipment purchase		$ 985,000
Co-venturer
Schedule of Equity Method Investments [Line Items]
Investments in joint venture				8,500,000
Co-Chief Executive Officer
Schedule of Equity Method Investments [Line Items]
Loan from related party				$ 850,000
Notes Payable | Co-Chief Executive Officer
Schedule of Equity Method Investments [Line Items]
Stated interest rate (percent)				6.00%

Segments (Details)

Segments (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2017USD ($)	Jun. 30, 2016USD ($)	Jun. 30, 2017USD ($)segment	Jun. 30, 2016USD ($)	Dec. 31, 2016USD ($)
Segment Reporting Information [Line Items]
Number of operating divisions | segment			2
Revenue	$ 7,590,540	$ 5,687,308	$ 14,437,305	$ 10,762,823
Gross profit	2,986,622	2,102,894	5,901,293	3,822,238
Identifiable assets	55,586,049		55,586,049		$ 23,741,361
Products and Services
Segment Reporting Information [Line Items]
Revenue	7,008,166	5,687,308	13,854,931	10,762,823
Gross profit	2,542,973	2,102,894	5,457,644	3,822,238
Identifiable assets	17,687,401		17,687,401		17,524,410
Energy Production
Segment Reporting Information [Line Items]
Revenue	774,192	0	774,192	0
Gross profit	443,649	0	443,649	0
Identifiable assets	16,288,369		16,288,369		0
Corporate, other and elimination
Segment Reporting Information [Line Items]
Revenue	(191,818)	0	(191,818)	0
Gross profit	0	0	0	0
Identifiable assets	21,610,279		21,610,279		$ 6,216,951
Operating Segments
Segment Reporting Information [Line Items]
Revenue	7,590,540	5,687,308	14,437,305	10,762,823
Operating Segments | Products and Services
Segment Reporting Information [Line Items]
Revenue	6,816,348	5,687,308	13,663,113	10,762,823
Operating Segments | Energy Production
Segment Reporting Information [Line Items]
Revenue	774,192	0	774,192	0
Operating Segments | Corporate, other and elimination
Segment Reporting Information [Line Items]
Revenue	0	0	0	0
Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenue	0	0	0	0
Intersegment Eliminations | Products and Services
Segment Reporting Information [Line Items]
Revenue	191,818	0	191,818	0
Intersegment Eliminations | Energy Production
Segment Reporting Information [Line Items]
Revenue	0	0	0	0
Intersegment Eliminations | Corporate, other and elimination
Segment Reporting Information [Line Items]
Revenue	$ (191,818)	$ 0	$ (191,818)	$ 0

Uncategorized Items - tgen-2017

Label	Element	Value
Cash Acquired from Acquisition	us-gaap_CashAcquiredFromAcquisition	$ 0