Sunnova Energy International (NOVA) 10-K 25 Feb 20 2019 FY Annual report Financial data

Cover Page

Cover Page - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Feb. 21, 2020	Jul. 29, 2019
Cover page.
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2019
Document Transition Report	false
Entity File Number	001-38995
Entity Registrant Name	Sunnova Energy International Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	30-1192746
Entity Address, Address Line One	20 East Greenway Plaza, Suite 475
Entity Address, City or Town	Houston
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77046
City Area Code	281
Local Phone Number	985-9904
Title of 12(b) Security	Common Stock, $0.0001 par value per share
Trading Symbol	NOVA
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 339.8
Entity Common Stock, Shares Outstanding		84,001,062
Documents Incorporated by Reference	Portions of the information called for by Part III of this Form 10-K are hereby incorporated by reference from either the definitive Proxy Statement for our annual meeting of stockholders or an amendment to this Form 10-K, either of which will be filed with the Securities and Exchange Commission not later than 120 days after December 31, 2019 .
Entity Central Index Key	0001772695
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Amendment Flag	false

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands		Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash		$ 83,485	$ 52,706
Accounts receivable—trade, net		10,672	6,312
Accounts receivable—other		6,147	3,721
Other current assets		174,016	26,794
Total current assets		274,320	89,533
Property and equipment, net		1,745,060	1,328,457
Customer notes receivable, net		297,975	172,031
Other assets		169,712	75,064
Total assets	[1]	2,487,067	1,665,085
Current liabilities:
Accounts payable		36,190	20,075
Accrued expenses		39,544	18,650
Current portion of long-term debt		97,464	26,965
Current portion of long-term debt—affiliates		0	16,500
Other current liabilities		21,804	13,214
Total current liabilities		195,002	95,404
Long-term debt, net		1,346,419	872,249
Long-term debt, net—affiliates		0	44,181
Other long-term liabilities		127,406	66,453
Total liabilities	[1]	1,668,827	1,078,287
Commitments and contingencies (Note 17)
Redeemable noncontrolling interests		172,305	85,680
Stockholders' equity:
Common stock		8	0
Additional paid-in capital—convertible preferred stock		0	701,326
Additional paid-in capital—common stock		1,007,751	85,439
Accumulated deficit		(361,824)	(286,312)
Total stockholders' equity		645,935	501,118
Total liabilities, redeemable noncontrolling interests and stockholders' equity		2,487,067	1,665,085
Series A convertible preferred stock
Stockholders' equity:
Convertible preferred stock		0	449
Series C convertible preferred stock
Stockholders' equity:
Convertible preferred stock		0	130
Series A Common Stock
Stockholders' equity:
Common stock		0	86
Series B Common Stock
Stockholders' equity:
Common stock		$ 0	$ 0
[1]	The consolidated assets as of December 31, 2019 and 2018 include $790,211 and $411,325 , respectively, of assets of variable interest entities ("VIEs") that can only be used to settle obligations of the VIEs. These assets include cash of $7,347 and $3,674 as of December 31, 2019 and 2018 , respectively; accounts receivable—trade, net of $1,460 and $884 as of December 31, 2019 and 2018 , respectively; accounts receivable—other of $4 and $109 as of December 31, 2019 and 2018 , respectively; other current assets of $47,606 and $4,821 as of December 31, 2019 and 2018 , respectively; property and equipment, net of $726,415 and $398,693 as of December 31, 2019 and 2018 , respectively; and other assets of $7,379 and $3,144 as of December 31, 2019 and 2018 , respectively. The consolidated liabilities as of December 31, 2019 and 2018 include $13,440 and $9,260 , respectively, of liabilities of VIEs whose creditors have no recourse to Sunnova Energy International Inc. These liabilities include accounts payable of $1,926 and $4,278 as of December 31, 2019 and 2018 , respectively; accrued expenses of $35 and $14 as of December 31, 2019 and 2018 , respectively; other current liabilities of $612 and $296 as of December 31, 2019 and 2018 , respectively; and other long-term liabilities of $10,867 and $4,672 as of December 31, 2019 and 2018 , respectively.

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands		Dec. 31, 2019	Dec. 31, 2018
Total assets	[1]	$ 2,487,067	$ 1,665,085
Cash		83,485	52,706
Accounts receivable—trade, net		10,672	6,312
Accounts receivable—other		6,147	3,721
Other current assets		174,016	26,794
Property and equipment, net		1,745,060	1,328,457
Other assets		169,712	75,064
Total liabilities	[1]	1,668,827	1,078,287
Accounts payable		36,190	20,075
Accrued expenses		39,544	18,650
Other current liabilities		21,804	13,214
Other long-term liabilities		$ 127,406	$ 66,453
Common stock, issued (in shares)		83,980,885	0
Common stock, par value (in USD per share)		$ 0.0001	$ 0.0001
Series A convertible preferred stock
Convertible preferred stock, issued (in shares)		0	44,942,594
Convertible preferred stock, par value (in USD per share)		$ 0.01	$ 0.01
Series C convertible preferred stock
Convertible preferred stock, issued (in shares)		0	13,006,780
Convertible preferred stock, par value (in USD per share)		$ 0.01	$ 0.01
Series A Common Stock
Common stock, issued (in shares)		0	8,612,728
Common stock, par value (in USD per share)		$ 0.01	$ 0.01
Series B Common Stock
Common stock, issued (in shares)		0	21,727
Common stock, par value (in USD per share)		$ 0.01	$ 0.01
Variable Interest Entity
Total assets		$ 790,211	$ 411,325
Cash		7,347	3,674
Accounts receivable—trade, net		1,460	884
Accounts receivable—other		4	109
Other current assets		47,606	4,821
Property and equipment, net		726,415	398,693
Other assets		7,379	3,144
Total liabilities		13,440	9,260
Accounts payable		1,926	4,278
Accrued expenses		35	14
Other current liabilities		612	296
Other long-term liabilities		$ 10,867	$ 4,672
[1]	The consolidated assets as of December 31, 2019 and 2018 include $790,211 and $411,325 , respectively, of assets of variable interest entities ("VIEs") that can only be used to settle obligations of the VIEs. These assets include cash of $7,347 and $3,674 as of December 31, 2019 and 2018 , respectively; accounts receivable—trade, net of $1,460 and $884 as of December 31, 2019 and 2018 , respectively; accounts receivable—other of $4 and $109 as of December 31, 2019 and 2018 , respectively; other current assets of $47,606 and $4,821 as of December 31, 2019 and 2018 , respectively; property and equipment, net of $726,415 and $398,693 as of December 31, 2019 and 2018 , respectively; and other assets of $7,379 and $3,144 as of December 31, 2019 and 2018 , respectively. The consolidated liabilities as of December 31, 2019 and 2018 include $13,440 and $9,260 , respectively, of liabilities of VIEs whose creditors have no recourse to Sunnova Energy International Inc. These liabilities include accounts payable of $1,926 and $4,278 as of December 31, 2019 and 2018 , respectively; accrued expenses of $35 and $14 as of December 31, 2019 and 2018 , respectively; other current liabilities of $612 and $296 as of December 31, 2019 and 2018 , respectively; and other long-term liabilities of $10,867 and $4,672 as of December 31, 2019 and 2018 , respectively.

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue	$ 131,556,000	$ 104,382,000	$ 76,856,000
Operating expense:
Cost of revenue—depreciation	43,536,000	34,710,000	25,896,000
Cost of revenue—other	3,877,000	2,007,000	1,444,000
Operations and maintenance	8,588,000	14,035,000	4,994,000
General and administrative	97,986,000	67,430,000	54,863,000
Other operating expense (income)	(161,000)	(70,000)	14,000
Total operating expense, net	153,826,000	118,112,000	87,211,000
Operating loss	(22,270,000)	(13,730,000)	(10,355,000)
Interest expense, net	108,024,000	51,582,000	59,847,000
Interest expense, net—affiliates	4,098,000	9,548,000	23,177,000
Interest income	(12,483,000)	(6,450,000)	(3,197,000)
Loss on extinguishment of long-term debt, net—affiliates	10,645,000	0	0
Other (income) expense	880,000	(1,000)	0
Loss before income tax	(133,434,000)	(68,409,000)	(90,182,000)
Income tax	0	0	0
Net loss	(133,434,000)	(68,409,000)	(90,182,000)
Net income attributable to redeemable noncontrolling interests	10,917,000	5,837,000	903,000
Net loss attributable to stockholders	(144,351,000)	(74,246,000)	(91,085,000)
Deemed dividends on convertible preferred stock exchange	0	(19,332,000)	0
Net loss attributable to common stockholders—basic	(169,076,000)	(135,872,000)	(121,288,000)
Net loss attributable to common stockholders—diluted	$ (169,076,000)	$ (135,872,000)	$ (121,288,000)
Net loss per share attributable to common stockholders—basic and diluted (in USD per share)	$ (4.14)	$ (15.74)	$ (14.05)
Weighted average common shares outstanding—basic and diluted (shares)	40,797,976	8,634,477	8,632,936
Series A convertible preferred stock
Operating expense:
Dividends earned on convertible preferred stock	$ (19,271,000)	$ (36,346,000)	$ (29,623,000)
Series B convertible preferred stock
Operating expense:
Dividends earned on convertible preferred stock	0	0	(580,000)
Series C convertible preferred stock
Operating expense:
Dividends earned on convertible preferred stock	$ (5,454,000)	$ (5,948,000)	$ 0

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss	$ (133,434)	$ (68,409)	$ (90,182)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	49,340	39,290	29,482
Impairment and loss on disposals, net	1,772	7,565	1,780
Amortization of deferred financing costs	9,822	9,074	14,568
Amortization of debt discount	3,018	1,083	759
Amortization of debt discount—affiliates	0	0	9,002
Non-cash effect of equity-based compensation plans	9,235	2,984	1,495
Non-cash payment-in-kind interest on loan—affiliates	2,716	5,524	3,569
Unrealized loss on derivatives	19,237	6,100	5,944
Unrealized loss on fair value option instruments	150	0	0
Loss on extinguishment of long-term debt, net—affiliates	10,645	0	0
Other non-cash items	8,442	4,818	3,080
Changes in components of operating assets and liabilities:
Accounts receivable	(9,349)	(4,983)	(841)
Dealer advances	0	(237)	(10,678)
Other current assets	(131,741)	(11,331)	(2,992)
Other assets	(40,118)	(8,529)	(4,473)
Accounts payable	5,292	(996)	(1,220)
Accrued expenses	15,099	4,234	1,381
Other current liabilities	8,452	4,938	5,876
Long-term debt—paid-in-kind—affiliates	(719)	(3,184)	(17,277)
Other long-term liabilities	1,879	489	1,760
Net cash used in operating activities	(170,262)	(11,570)	(48,967)
CASH FLOWS FROM INVESTING ACTIVITIES
Purchases of property and equipment	(430,822)	(252,618)	(240,578)
Payments for investments and customer notes receivable	(159,303)	(108,354)	(52,405)
Proceeds from customer notes receivable	21,604	7,715	2,816
State utility rebates and tax credits	668	853	621
Other, net	(463)	3,555	413
Net cash used in investing activities	(568,316)	(348,849)	(289,133)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from long-term debt	883,360	445,586	734,494
Payments of long-term debt	(342,540)	(292,091)	(374,550)
Proceeds of long-term debt from affiliates	15,000	15,000	95,000
Payments of long-term debt to affiliates	(56,236)	(40,000)	(215,840)
Payments on notes payable	(4,672)	0	(247)
Payments of deferred financing costs	(12,110)	(8,598)	(27,627)
Payments of debt discounts	(1,084)	(2,465)	(375)
Proceeds from issuance of common stock, net	164,452	0	23
Proceeds from equity component of debt instrument, net	13,984	0	0
Proceeds from issuance of convertible preferred stock, net	(2,510)	172,771	89,890
Contributions from redeemable noncontrolling interests	157,149	79,017	72,223
Distributions to redeemable noncontrolling interests	(7,559)	(2,017)	(294)
Payments of costs related to redeemable noncontrolling interests	(5,395)	(1,510)	(2,714)
Other, net	(16)	(6)	(90)
Net cash provided by financing activities	801,823	365,687	369,893
Net increase in cash and restricted cash	63,245	5,268	31,793
Cash and restricted cash at beginning of period	87,046	81,778	49,985
Cash and restricted cash at end of period	150,291	87,046	81,778
Restricted cash included in other current assets	(10,474)	(5,190)	(4,555)
Restricted cash included in other assets	(56,332)	(29,150)	(20,905)
Cash at end of period	83,485	52,706	56,318
Non-cash investing and financing activities:
Change in accounts payable and accrued expenses related to purchases of property and equipment	26,952	3,191	23,156
Change in accounts payable and accrued expenses related to payments for investments and customer notes receivable	(10,557)	(10,461)	(6,178)
Non-cash issuance of convertible preferred stock relating to the reduction of debt	0	0	15,190
Supplemental cash flow information:
Cash paid for interest	58,060	57,887	59,896
Cash paid for income taxes	$ 0	$ 0	$ 0

CONSOLIDATED STATEMENTS OF REDE

CONSOLIDATED STATEMENTS OF REDEEMABLE NONCONTROLLING INTERESTS AND STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Series A Convertible Preferred Stock	Series B Convertible Preferred Stock	Series C Convertible Preferred Stock	Convertible Preferred Stock	Convertible Preferred StockSeries A Convertible Preferred Stock	Convertible Preferred StockSeries B Convertible Preferred Stock	Convertible Preferred StockSeries C Convertible Preferred Stock	Common Stock	Common StockSeries A Common Stock	Common StockSeries B Common Stock	Treasury StockSeries A Treasury Stock	Treasury StockSeries B Treasury Stock	Additional Paid-in Capital - Convertible Preferred Stock	Additional Paid-in Capital - Common Stock	Accumulated Deficit
Redeemable noncontrolling interest, beginning balance at Dec. 31, 2016	$ 0
Increase (Decrease) in Redeemable Noncontrolling Interests [Roll Forward]
Net income (loss)	903
Contributions from redeemable noncontrolling interests	72,223
Distributions to redeemable noncontrolling interests	(294)
Costs related to redeemable noncontrolling interests	(3,575)
Equity in subsidiaries attributable to parent	(30,385)
Other, net	(282)
Redeemable noncontrolling interest, ending balance at Dec. 31, 2017	38,590
Stockholders' equity, beginning balance (in shares) at Dec. 31, 2016						34,923,648	0	0	0	8,618,156	11,501
Stockholders' equity, beginning balance at Dec. 31, 2016	325,466					$ 349	$ 0	$ 0	$ 0	$ 86	$ 0	$ 0	$ (1)	$ 426,060	$ 80,975	$ (182,003)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(91,085)															(91,085)
Issuance of stock, net (in shares)		4,033,061	4,583,576			4,033,061	4,583,576				12,712
Issuance of stock, net	16				$ 89,800	$ 40	$ 46							89,714	16
Non-cash exchange of convertible preferred stock					15,190	12								15,178
Equity in subsidiaries attributable to parent	30,385															30,385
Equity-based compensation expense	1,495														1,495
Acquisition of treasury stock	(84)											(52)	(32)
Retirement of treasury stock (in shares)										(5,428)	(2,486)
Retirement of treasury stock												52	33		(30)	(55)
Other, net	0					$ 1								(1)	(1)	1
Stockholders' equity, ending balance (in shares) at Dec. 31, 2017						40,179,508	4,583,576	0	0	8,612,728	21,727
Stockholders' equity, ending balance at Dec. 31, 2017	371,183					$ 402	$ 46	$ 0	$ 0	$ 86	$ 0	0	0	530,951	82,455	(242,757)
Increase (Decrease) in Redeemable Noncontrolling Interests [Roll Forward]
Net income (loss)	5,837
Contributions from redeemable noncontrolling interests	79,017
Distributions to redeemable noncontrolling interests	(2,017)
Distributions payable to redeemable noncontrolling interests	(3,988)
Costs related to redeemable noncontrolling interests	(1,062)
Equity in subsidiaries attributable to parent	(30,697)
Redeemable noncontrolling interest, ending balance at Dec. 31, 2018	85,680
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(74,246)															(74,246)
Issuance of stock, net (in shares)				13,006,780			13,013	13,006,780			644
Issuance of stock, net	(2)				$ 170,506			$ 130						170,376	(2)
Non-cash exchange of convertible preferred stock (in shares)						4,763,086	(4,596,589)
Non-cash exchange of convertible preferred stock						$ 48	$ (46)							(2)
Equity in subsidiaries attributable to parent	30,697															30,697
Equity-based compensation expense	2,984														2,984
Acquisition of treasury stock	(4)												(4)
Retirement of treasury stock (in shares)											(644)
Retirement of treasury stock													4		2	(6)
Other, net						$ (1)								1
Stockholders' equity, ending balance (in shares) at Dec. 31, 2018						44,942,594	0	13,006,780	0	8,612,728	21,727
Stockholders' equity, ending balance at Dec. 31, 2018	501,118					$ 449	$ 0	$ 130	$ 0	$ 86	$ 0	0	0	701,326	85,439	(286,312)
Increase (Decrease) in Redeemable Noncontrolling Interests [Roll Forward]
Net income (loss)	10,917
Contributions from redeemable noncontrolling interests	157,149
Distributions to redeemable noncontrolling interests	(7,559)
Distributions payable to redeemable noncontrolling interests	2,358
Costs related to redeemable noncontrolling interests	(7,392)
Equity in subsidiaries attributable to parent	(68,848)
Redeemable noncontrolling interest, ending balance at Dec. 31, 2019	172,305
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(144,351)															(144,351)
Issuance of stock, net (in shares)									14,865,267		2,143
Issuance of stock, net	163,966								$ 1						163,965
Repurchase of convertible preferred stock (in shares)						(13,484)
Repurchase of convertible preferred stock	(191)													(183)		(8)
Non-cash conversion of convertible notes for Series A and Series C convertible preferred stock (in shares)						1,422,767		1,120,360
Non-cash conversion of convertible notes for Series A and Series C convertible preferred stock	32,834					$ 14		$ 11						32,809
Non-cash exchange of convertible preferred stock (in shares)						(46,351,877)		(14,127,140)	69,115,618	(8,612,731)	(23,870)
Non-cash exchange of convertible preferred stock						$ (464)		$ (141)	$ 7	$ (86)				(734,444)	735,128
Equity component of debt instrument, net	13,984														13,984
Equity in subsidiaries attributable to parent	68,848															68,848
Equity-based compensation expense	9,235														9,235
Other, net (in shares)										3
Other, net	492					$ 1								492		(1)
Stockholders' equity, ending balance (in shares) at Dec. 31, 2019						0	0	0	83,980,885	0	0
Stockholders' equity, ending balance at Dec. 31, 2019	$ 645,935					$ 0	$ 0	$ 0	$ 8	$ 0	$ 0	$ 0	$ 0	$ 0	$ 1,007,751	$ (361,824)

Description of Business and Bas

Description of Business and Basis of Presentation	12 Months Ended
	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business and Basis of Presentation	Description of Business and Basis of Presentation We are a leading residential solar and energy storage service provider, serving more than 80,000 customers in more than 20 United States ("U.S.") states and territories. Sunnova Energy Corporation was incorporated in Delaware on October 22, 2012 and formed Sunnova Energy International Inc. ("SEI") as a Delaware corporation on April 1, 2019. We completed our initial public offering on July 29, 2019 (our "IPO"); and in connection with our IPO, all of Sunnova Energy Corporation's ownership interests were contributed to SEI. Unless the context otherwise requires, references in this report to "Sunnova," the "Company," "we," "our," "us," or like terms, refer to SEI and its subsidiaries. We have a differentiated residential solar dealer model in which we partner with local dealers who originate, design and install our customers' solar energy systems and energy storage systems on our behalf. Our focus on our dealer model enables us to leverage our dealers' specialized knowledge, connections and experience in local markets to drive customer origination while providing our dealers with access to high quality products at competitive prices and technical oversight and expertise. We believe this structure provides operational flexibility , reduced exposure to labor shortages and lower fixed costs relative to our peers, furthering our competitive advantage. We provide our services through long-term residential solar service agreements with a diversified pool of high credit quality customers. Our solar service agreements typically are structured as either a legal-form lease (a "lease") of a solar energy system to the customer, the sale of the solar energy system's output to the customer under a power purchase agreement ("PPA") or the purchase of a solar energy system with financing provided by us (a "loan"). The initial term of our solar service agreements is typically either 10 or 25 years , during which time we provide or arrange for ongoing services to customers, including monitoring, maintenance and warranty services. Our lease and PPA agreements typically include an opportunity for customers to renew for up to an additional 10 years , via two five -year renewal options. Customer payments and rates can be fixed for the duration of the solar service agreement or escalated at a pre-determined percentage annually. We also receive tax benefits and other incentives from leases and PPAs, a portion of which we finance through tax equity, non-recourse debt structures and hedging arrangements in order to fund our upfront costs, overhead and growth investments. Basis of Presentation The accompanying annual audited consolidated financial statements (" consolidated financial statements ") include our consolidated balance sheets, statements of operations, statements of redeemable noncontrolling interests and stockholders' equity and statements of cash flows and have been prepared in accordance with accounting principles generally accepted in the United States of America ("GAAP") from records maintained by us. Our consolidated financial statements reflect our accounts and operations and those of our subsidiaries in which we have a controlling financial interest. In accordance with the provisions of the Financial Accounting Standards Board ("FASB") Accounting Standards Codification ("ASC") 810, Consolidation , we consolidate any VIE of which we are the primary beneficiary. We form VIEs with our investors in the ordinary course of business to facilitate the funding and monetization of certain attributes associated with our solar energy systems. The typical condition for a controlling financial interest ownership is holding a majority of the voting interests of an entity; however, a controlling financial interest may also exist in entities, such as VIEs, through arrangements that do not involve controlling voting interests. ASC 810 requires a variable interest holder to consolidate a VIE if that party has (a) the power to direct the activities of the VIE that most significantly impact the VIE's economic performance and (b) the obligation to absorb losses or the right to receive benefits from the VIE that could potentially be significant to the VIE. We do not consolidate a VIE in which we have a majority ownership interest when we are not considered the primary beneficiary. We have considered the provisions within the contractual arrangements that grant us power to manage and make decisions that affect the operation of our VIEs, including determining the solar energy systems contributed to the VIEs, and the installation, operation and maintenance of the solar energy systems. We consider the rights granted to the other investors under the contractual arrangements to be more protective in nature rather than participating rights. As such, we have determined we are the primary beneficiary of our VIEs and evaluate our relationships with our VIEs on an ongoing basis to ensure we continue to be the primary beneficiary. We have eliminated all intercompany accounts and transactions in consolidation. Corporate Reorganization In connection with our IPO, we implemented an internal reorganization that resulted in SEI owning all the outstanding capital stock of Sunnova Energy Corporation (the "Reorganization"). In connection with the Reorganization, a direct, wholly-owned subsidiary of SEI merged with and into Sunnova Energy Corporation, with Sunnova Energy Corporation surviving as a direct, wholly owned subsidiary of SEI. Each share of each class of Sunnova Energy Corporation stock issued and outstanding immediately prior to the Reorganization, by virtue of the Reorganization and without any action on the part of the holders thereof, automatically converted into an equivalent corresponding share of stock of SEI, having the same designations, rights, powers and preferences and the qualifications, limitations and restrictions with respect to SEI as each such corresponding share of Sunnova Energy Corporation stock being converted had with respect to Sunnova Energy Corporation. Accordingly, upon consummation of the Reorganization, each of Sunnova Energy Corporation's stockholders immediately prior to the consummation of the Reorganization became a stockholder of SEI. Reverse Stock Split In connection with our IPO, we decreased the total number of outstanding shares with a 1 for 2.333 reverse stock split effective July 29, 2019 (the "Reverse Stock Split"). All current and past period amounts stated herein have given effect to the Reverse Stock Split. Reclassifications Certain prior period amounts have been reclassified to conform to the current period presentation. These reclassifications did not have a significant impact on our consolidated financial statements .

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Significant Accounting Policies	Significant Accounting Policies Use of Estimates The application of GAAP in the preparation of the consolidated financial statements requires us to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. We base our estimates on historical experience and on various other assumptions believed to be reasonable, the results of which form the basis for making judgments about the carrying values of assets and liabilities. Actual results could differ materially from those estimates. Cash We maintain cash, which consists principally of demand deposits, with investment-grade financial institutions. We are exposed to credit risk to the extent cash balances exceed amounts covered by the Federal Deposit Insurance Corporation ("FDIC"). As of December 31, 2019 and 2018 , we had cash deposits of $72.4 million and $46.3 million , respectively, in excess of the FDIC's current insured limit of $250,000. We have not experienced any losses on our deposits of cash. Restricted Cash We record cash that is restricted as to withdrawal or use under the terms of certain contractual agreements as restricted cash. Our restricted cash primarily represents cash held to service certain payments under the Sunnova AP 6 Warehouse II, LLC ("AP6WII"), Helios Issuer, LLC ("HELI"), Sunnova LAP Holdings, LLC ("LAPH"), Sunnova EZ-Own Portfolio, LLC ("EZOP"), Sunnova TEP I, LLC ("TEPI"), Sunnova TEP I Holdings, LLC ("TEPIH"), Sunnova TEP II, LLC ("TEPII"), Sunnova TEP II-B, LLC ("TEPIIB"), Sunnova TEP III, LLC ("TEPIII"), Sunnova TEP IV-A, LLC ("TEPIVA"), Sunnova TEP IV-B, LLC ("TEPIVB"), Sunnova TEP Holdings, LLC ("TEPH"), Sunnova TEP II Holdings, LLC ("TEPIIH"), Helios II Issuer, LLC ("HELII"), Helios III Issuer, LLC ("HELIII"), Sunnova RAYS I Issuer, LLC ("RAYSI") and Sunnova TEP Inventory, LLC ("TEPINV") financing arrangements (see Note 8, Long-Term Debt and Note 13, Redeemable Noncontrolling Interests ) and balances collateralizing outstanding letters of credit related to one of our operating leases for office space (see Note 17, Commitments and Contingencies ). The following table presents the detail of restricted cash as recorded in other current assets and other assets in the consolidated balance sheets: As of December 31, 2019 2018 (in thousands) Debt and inverter reserves $ 55,407 $ 28,225 Tax equity reserves 9,904 4,796 Letters of credit for office lease 725 725 Other 770 594 Total (1) $ 66,806 $ 34,340 (1) Of this amount, $10.5 million and $5.2 million is recorded in other current assets as of December 31, 2019 and 2018 , respectively. We are exposed to credit risk to the extent restricted cash balances exceed amounts covered by the FDIC. As of December 31, 2019 and 2018 , we had restricted cash deposits of $63.6 million and $31.8 million , respectively, in excess of the FDIC's current insured limit of $250,000. We have not experienced any losses on our deposits of restricted cash. Accounts Receivable Accounts Receivable — Trade. Accounts receivable — trade primarily represents trade receivables from residential customers under PPAs and leases that are generally collected in the subsequent month and recorded at net realizable value. We maintain an allowance for doubtful accounts to reserve for potentially uncollectible accounts receivable. We review our accounts receivable by aging category to identify customers with known disputes or collection issues. We write off accounts receivable when we deem them uncollectible. The following table presents the changes in the allowance for doubtful accounts recorded against accounts receivable — trade, net in the consolidated balance sheets: As of December 31, 2019 2018 (in thousands) Balance at beginning of period $ 723 $ 427 Bad debt expense 1,645 1,119 Write off of uncollectible accounts (1,498 ) (861 ) Recoveries 90 50 Other, net — (12 ) Balance at end of period $ 960 $ 723 Accounts Receivable — Other. Accounts receivable — other primarily represents amounts owed from dealers in a net receivable position primarily as a result of customer contract cancelations or settlement agreements and receivables related to the sale of inventory. Inventory Inventory primarily represents energy storage systems, photovoltaic modules, inverters, meters and other associated equipment purchased and held for use as original parts on new solar energy systems or replacement parts on existing solar energy systems. We record inventory in other current assets in the consolidated balance sheets at the lower of cost and net realizable value. We remove these items from inventory using the weighted-average method and (a) expense to operations and maintenance expense when installed as a replacement part for a solar energy system or (b) capitalize to property and equipment when installed as an original part on a solar energy system. We evaluate our inventory reserves and write down the estimated value of excess and obsolete inventory based upon assumptions about future demand and market conditions. The following table presents the detail of inventory as recorded in other current assets in the consolidated balance sheets: As of December 31, 2019 2018 (in thousands) Energy storage systems and components $ 33,443 $ 8,394 Modules and inverters 10,137 433 Meters 169 360 Total $ 43,749 $ 9,187 As of December 31, 2019 , we recorded accrued expenses of $15.2 million for inventory purchases. Concentrations of Risk Financial instruments that potentially subject us to concentrations of credit risk consist primarily of cash, restricted cash, accounts receivable and notes receivable. The concentrated risk associated with cash and restricted cash is mitigated by our policy of banking with creditworthy institutions. Typically, amounts on deposit with certain banking institutions exceed FDIC insurance limits. We do not generally require collateral or other security to support accounts receivable. To reduce credit risk related to our relationship with our dealers, management performs periodic credit evaluations and ongoing assessments of our dealers' financial condition. Concentration of Services and Equipment from Dealers We utilize a network of approximately 100 dealers as of December 31, 2019 . During the year ended December 31, 2019 , two dealers accounted for approximately 49% and 10% of our total expenditures to dealers relating to costs incurred for solar energy systems. During the year ended December 31, 2018 , one dealer accounted for approximately 58% of our total expenditures to dealers. During the year ended December 31, 2017 , three dealers accounted for approximately 32% , 27% and 13% , respectively, of our total expenditures to dealers. No other dealer accounted for more than 10% of our expenditures for solar energy systems during the years ended December 31, 2019 , 2018 and 2017 . Dealer Commitments Throughout 2019, we entered into exclusivity and other similar agreements with certain key dealers pursuant to which we have agreed to pay an incentive if such dealers install a certain minimum number of solar energy systems within specified periods. These incentives are recorded in other assets in the consolidated balance sheets and are amortized to general and administrative expense in the consolidated statements of operations generally over the term of the customer agreements, which is estimated at an average of 23 years . See Note 17, Commitments and Contingencies . Fair Value of Financial Instruments Fair value is an exit price representing the amount 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. As such, fair value is a market-based measurement that should be determined based on assumptions market participants would use in pricing an asset or a liability. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. ASC 820 establishes a three-tier fair value hierarchy, which prioritizes inputs that may be used to measure fair value as follows: • Level 1—Observable inputs that reflect unadjusted quoted market prices in active markets for identical assets or liabilities that are accessible at the measurement date. • Level 2—Observable inputs other than Level 1 prices, such as quoted market prices for similar assets or liabilities in active markets, quoted market prices 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 assets or liabilities. • 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. In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, the level in the fair value hierarchy must be determined based on the lowest level input that is significant to the fair value measurement. An assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment and consideration of factors specific to the asset or liability. Our financial instruments include accounts receivable, notes receivable, accounts payable, accrued expenses, long-term debt and interest rate swaps and swaptions. The carrying values of accounts receivable, accounts payable and accrued expenses approximate the fair values due to the fact that they are short-term in nature (Level 1). We estimate the fair value of our customer notes receivable based on interest rates currently offered under the loan program with similar maturities and terms (Level 3). We estimate the fair value of our fixed-rate long-term debt, excluding the senior secured notes for which we selected the fair value option and the convertible senior notes, based on interest rates currently offered for debt with similar maturities and terms (Level 3). We estimate the fair value of the senior secured notes and convertible senior notes based on a market approach model using Level 3 inputs that incorporates a binomial tree model and a discounted future cash flow model. We determine the fair values of the interest rate derivative transactions based on a discounted cash flow method using contractual terms of the transactions. The floating interest rate is based on observable rates consistent with the frequency of the interest cash flows (Level 2). See Note 7, Customer Notes Receivable , Note 8, Long-Term Debt and Note 9, Derivative Instruments . Changes in fair value of the senior secured notes are included in other (income) expense in the consolidated statements of operations. The following table summarizes the change in fair value of our financial liabilities accounted for at fair value on a recurring basis using Level 3 inputs as recorded in long-term debt, net—affiliates in the consolidated balance sheets: As of December 31, 2019 2018 (in thousands) Balance at beginning of period $ — $ — Additions 55,506 — Change in fair value 730 — Extinguishment (56,236 ) — Balance at end of period $ — $ — Derivative Instruments Our derivative instruments consist of interest rate swaps and swaptions that are not designated as cash flow hedges or fair value hedges under accounting guidance. We use interest rate swaps and swaptions to manage our net exposure to interest rate changes. We record the derivatives in other current assets, other assets, other current liabilities and other long-term liabilities, as appropriate, in the consolidated balance sheets and the changes in fair value are recorded in interest expense, net in the consolidated statements of operations. We include unrealized gains and losses on derivatives as a non-cash reconciling item in operating activities in the consolidated statements of cash flows. We include realized gains and losses on derivatives as a change in components of operating assets and liabilities in operating activities in the consolidated statements of cash flows. See Note 9, Derivative Instruments . Revenue The following table presents the detail of revenue as recorded in the consolidated statements of operations: Year Ended 2019 2018 2017 (in thousands) PPA revenue $ 48,041 $ 38,950 $ 29,171 Lease revenue 40,191 33,079 21,866 Solar renewable energy certificate revenue 38,453 30,630 24,833 Loan revenue 1,645 933 479 Other revenue 3,226 790 507 Total $ 131,556 $ 104,382 $ 76,856 We recognize revenue from contracts with customers as we satisfy our performance obligations at a transaction price reflecting an amount of consideration based upon an estimated rate of return. We express this rate of return as the solar rate per kilowatt hour ("kWh") in the customer contract. The amount of revenue we recognize does not equal customer cash payments because we satisfy performance obligations ahead of cash receipt or evenly as we provide continuous access on a stand-ready basis to the solar energy system. We reflect the differences between revenue recognition and cash payments received in accounts receivable, other assets or deferred revenue, as appropriate. Revenue allocated to remaining performance obligations represents contracted revenue we have not yet recognized and includes deferred revenue as well as amounts that will be invoiced and recognized as revenue in future periods. Contracted but not yet recognized revenue was approximately $1.1 billion as of December 31, 2019 , of which we expect to recognize approximately 4% over the next 12 months . We do not expect the annual recognition to vary significantly over approximately the next 20 years as the vast majority of existing solar service agreements have at least 20 years remaining , given the average age of the fleet of solar energy systems under contract is less than three years . PPAs. Customers purchase electricity from us under PPAs. Pursuant to ASC 606, we recognize revenue based upon the amount of electricity delivered as determined by remote monitoring equipment at solar rates specified under the PPAs. All customers must pass our credit evaluation process. The PPAs generally have a term of 25 years with an opportunity for customers to renew for up to an additional 10 years , via two five -year renewal options. Leases . We are the lessor under lease agreements for solar energy systems and energy storage systems, which do not meet the definition of a lease under ASC 842 and are accounted for as contracts with customers under ASC 606. We recognize revenue on a straight-line basis over the contract term as we satisfy our obligation to provide continuous access to the solar energy system. All customers must pass our credit evaluation process. The lease agreements generally have a term of 25 years with an opportunity for customers to renew for up to an additional 10 years , via two five -year renewal options. We provide customers under our lease agreements a performance guarantee that each solar energy system will achieve a certain specified minimum solar energy production output, which is a significant proportion of its expected output. The specified minimum solar energy production output may not be achieved due to natural fluctuations in the weather or equipment failures from exposure and wear and tear outside of our control, among other factors. We determine the amount of the guaranteed output based on a number of different factors, including: (a) the specific site information relating to the tilt of the panels, azimuth (a horizontal angle measured clockwise in degrees from a reference direction) of the panels, size of the system, and shading on site; (b) the calculated amount of available irradiance (amount of energy for a given flat surface facing a specific direction) based on historical average weather data and (c) the calculated amount of energy output of the solar energy system. While actual irradiance levels can significantly change year over year due to natural fluctuations in the weather, we expect the levels to average out over the term of a 25-year lease and to approximate the levels used in determining the amount of the performance guarantee. Generally, weather fluctuations are the most likely reason a solar energy system may not achieve a certain specified minimum solar energy production output. If the solar energy system does not produce the guaranteed production amount, we are required to refund a portion of the previously remitted customer payments, where the repayment is calculated as the product of (a) the shortfall production amount and (b) the dollar amount (guaranteed rate) per kWh that is fixed throughout the term of the contract. These remittances of a customer's payments, if needed, are payable in January following the end of the first three years of the solar energy system's placed in service date and then every annual period thereafter. See Note 17, Commitments and Contingencies . Solar Renewable Energy Certificates. Each solar renewable energy certificate ("SREC") represents one megawatt hour ( 1,000 kWh) generated by a solar energy system. SRECs can be sold with or without the actual electricity associated with the renewable-based generation source. We account for the SRECs we generate from our solar energy systems as governmental incentives with no costs incurred to obtain them and do not consider those SRECs output of the underlying solar energy systems. We classify these SRECs as inventory held until sold and delivered to third parties. As we did not incur costs to obtain these governmental incentives, the inventory carrying value for the SRECs was $0 as of December 31, 2019 and 2018 . We enter into economic hedges related to expected production of SRECs through forward contracts. The contracts require us to physically deliver the SRECs upon settlement. We recognize the related revenue under ASC 606 upon satisfaction of the performance obligation to transfer the SRECs to the stated counterparty. Payments are typically received within one month of transferring the SREC to the counterparty. The costs related to the sales of SRECs are limited to broker fees (included in cost of revenue—other), which are only paid in connection with certain transactions. Loans. See discussion of loan revenue in the "Loans" section below. Other Revenue. Other revenue includes certain state incentives, revenue from the direct sale of energy storage systems to customers and sales of service plans. We recognize revenue from state incentives in the periods in which they are incurred. We recognize revenue from the direct sale of energy storage systems in the period in which the storage components are placed in service. Service plans are available to customers whose solar energy system was not originally sold by Sunnova. We recognize revenue from service plan contracts over the life of the contract, which is typically five years . Loans We offer a loan program, under which the customer finances the purchase of a solar energy system or energy storage system through a solar service agreement, typically for a term of 10 or 25 years . We recognize cash payments received from customers on a monthly basis under our loan program (a) as interest income, to the extent attributable to earned interest on the contract that financed the customer's purchase of the solar energy system or energy storage system; (b) as a reduction of a note receivable on the balance sheet, to the extent attributable to a return of principal (whether scheduled or prepaid) on the contract that financed the customer's purchase of the solar energy system or energy storage system; and (c) as revenue, to the extent attributable to payments for operations and maintenance services provided by us. To qualify for the loan program, a customer must pass our credit evaluation process, which requires the customer to have a minimum FICO ® score of 650 to 720 depending on certain circumstances, and we secure the loans with the solar energy systems or energy storage systems financed. In determining the allowance for uncollectible notes receivable, we identify customers with known disputes or collection issues and consider our historical level of credit losses and current economic trends that might impact the level of future credit losses. We write off customer notes receivable when they are deemed uncollectible. In addition, there were no customer notes receivable not accruing interest and $151,000 and $81,000 of past due customer notes receivable as of December 31, 2019 and 2018 , respectively. See Note 7, Customer Notes Receivable . The following table presents the changes in the allowance for losses recorded against customer notes receivable in the consolidated balance sheets: As of December 31, 2019 2018 (in thousands) Balance at beginning of period $ 710 $ 602 Bad debt expense 419 238 Write off of uncollectible accounts (38 ) (130 ) Balance at end of period $ 1,091 $ 710 Deferred Revenue Deferred revenue consists of amounts for which the criteria for revenue recognition have not yet been met and includes (a) down payments and partial or full prepayments from customers, (b) differences due to the timing of energy production versus billing for certain types of PPAs and (c) payments for unfulfilled performance obligations from the loan program which will be recognized over the remaining term of the respective solar service agreements. Deferred revenue was $19.0 million as of December 31, 2017 . The following table presents the detail of deferred revenue as recorded in other current liabilities and other long-term liabilities in the consolidated balance sheets: As of December 31, 2019 2018 (in thousands) Loans $ 46,958 $ 27,793 PPAs and leases 8,895 6,255 SRECs 3,000 — Total (1) $ 58,853 $ 34,048 (1) Of this amount, $2.1 million and $1.6 million is recorded in other current liabilities as of December 31, 2019 and 2018 , respectively. During the years ended December 31, 2019 and 2018 , we recognized revenue of $3.0 million and $2.0 million , respectively, from amounts included in deferred revenue at the beginning of the respective periods. Performance Guarantee Obligations We guarantee certain specified minimum solar energy production output under our leases and loan agreements, generally over a term of 25 years . The amounts are generally measured and credited to the customer's account in January following the end of the first three years of the solar energy system's placed in service date and then every annual period thereafter. We monitor the solar energy systems to ensure these outputs are achieved. We evaluate if any amounts are due to our customers based upon not meeting the guaranteed solar energy production outputs at each reporting period end. For leases, these estimated amounts are recorded as a reduction to revenues from customers and a current or long-term liability, as applicable. For loans, these estimated amounts are recorded as an increase to cost of revenue—other and a current or long-term liability, as applicable. See Note 17, Commitments and Contingencies . Property and Equipment Solar Energy Systems. Depreciation and amortization of solar energy systems are calculated using the straight-line method over the estimated useful lives of the solar energy systems and are included in cost of revenue—depreciation. While solar energy systems are in the design, construction and installation stages prior to being placed in service, the development of the systems is accounted for through construction in progress. The components of the design, construction and installation of the solar energy systems, which are installed on or near residential rooftops, are as follows: • Dealer's costs (engineering, procurement and construction) • Direct costs (costs directly related to a solar energy system) • Indirect costs (costs incurred in the design, construction and installation of the solar energy system but not directly associated with a particular asset) Solar energy systems are carried at the cost of acquisition or construction (including design and installation) less certain utility rebates and federal and state tax incentives (including federal investment tax credits, known as "Section 48(a) ITCs") and are depreciated over the useful lives of the assets. We account for the Section 48(a) ITCs in accordance with the deferral gross up method, thus reducing the cost basis of the qualifying solar energy systems by the rate applicable to Section 48(a) ITCs, currently 30% for qualifying solar energy systems that began construction before 2020. However, as discussed in Note 10, Income Taxes , we have a full valuation allowance, which is recorded against deferred income taxes and requires the gross up of the basis of the qualifying solar energy systems back to the full value. Depreciation begins when a solar energy system is placed in service. Costs associated with repair and maintenance of a solar energy system are expensed as incurred. Costs associated with improvements to a solar energy system, which extend the life, increase the capacity or improve the efficiency of the systems, are capitalized and depreciated over the remaining life of the asset. Property and Equipment, Excluding Solar Energy Systems . Property and equipment, including information technology system projects, computers and equipment, leasehold improvements, furniture and fixtures, vehicles and other property and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation and amortization are calculated using the straight-line method over the estimated useful lives of the respective assets and are included in general and administrative expense. Leasehold improvements are amortized over the shorter of the lease term or the estimated useful lives. Upon disposition, the cost and related accumulated depreciation of the assets are removed from property and equipment and the resulting gain or loss is reflected in the consolidated statements of operations. Repair and maintenance costs are expensed as incurred. Capitalization of Interest Costs . We capitalize interest on solar energy systems during the development, design, installation and test phase (construction), generally over a period of four months . We determine which debt instruments represent a reasonable measure of the cost of financing construction in terms of interest costs incurred that otherwise could have been avoided. Interest can only be capitalized for debt instruments related to financing the construction of solar energy systems; interest cannot be capitalized for debt instruments related to the acquisition of solar energy systems already constructed and/or in service. These debt instruments and associated interest costs are included in the calculation of the weighted average interest rate used for determining the capitalization rate. Once a solar energy system is placed in service, capitalized interest, as a component of the total cost of the construction, is depreciated over the estimated useful life of the solar energy system. Intangibles Our intangible assets primarily consist of a software license and a trademark related to the design process of solar energy systems and are stated at cost less accumulated amortization. We amortize intangible assets to general and administrative expense over a useful life of three years using the straight-line method. The following table presents the detail of intangible assets as recorded in other assets in the consolidated balance sheets: As of December 31, 2019 2018 (in thousands) Software license $ 331 $ 331 Trademark 68 68 Other 88 — Intangibles, gross 487 399 Less: accumulated amortization (420 ) (399 ) Intangibles, net $ 67 $ — As of December 31, 2019 , amortization expense related to intangible assets to be recognized is $29,000 per year for 2020 and 2021 , $9,000 for 2022 and $0 thereafter. Deferred Financing Costs Deferred financing costs are capitalized and amortized to interest expense, net over the term of the related debt using the effective interest method for term loans or the straight-line method for revolving credit facilities. The unamortized balance of deferred financing costs is included in current portion of long-term debt, current portion of long-term debt—affiliates, long-term debt, net and long-term debt, net—affiliates (see Note 8, Long-Term Debt ) for term loans or in other current assets and other assets for revolving credit facilities and debt and equity transactions not yet completed, in the consolidated balance sheets. The following table presents the changes in net deferred financing costs: As of December 31, 2019 2018 (in thousands) Balance at beginning of period $ 22,712 $ 25,188 Capitalized 12,731 6,598 Amortized (9,822 ) (9,074 ) Balance at end of period $ 25,621 $ 22,712 AROs We have AROs arising from contractual requirements to perform certain asset retirement activities at the time the solar energy systems are disposed. We recognize an ARO at the point an obligating event takes place, typically when the solar energy system is placed in service. An asset is considered retired when it is permanently taken out of service, such as through a sale or disposal. The liability is initially measured at fair value (as a Level 3 measurement) based on the present value of estimated removal and restoration costs and subsequently adjusted for changes in the underlying assumptions and for accretion expense. The accretion expense is recognized in general and administrative expense in the consolidated statements of operations. The corresponding asset retirement costs are capitalized as part of the carrying amount of the solar energy system and depreciated (for which the expense is included in cost of revenue — depreciation) over the solar energy system's remaining useful life. See Note 6, AROs . Warranty Obligations In connection with our solar service agreements, we warrant the solar energy systems against defects in workmanship, against component or materials breakdowns and against any damages to rooftops during the installation process. The dealers' warranties on the workmanship, including work during the installation process, and the manufacturers' warranties over component parts have a range of warranty periods which are generally 10 to 25 years . As of December 31, 2019 and 2018 , we recorded a warranty reserve of an insignificant amount . Advertising Costs We expense advertising costs as they are incurred to general and administrative expense in the consolidated statements of operations. We recognized advertising expense of $1.0 million , $191,000 and $52,000 during the years ended December 31, 2019 , 2018 and 2017 , respectively. Defined Contribution Plan In April 2015, we established the Sunnova Energy Corporation 401(k) Profit Sharing Plan ("401(k) plan") available to employees who meet the 401(k) plan's eligibility requirements. The 401(k) plan allows participants to contribute a percentage of their compensation to the 401(k) plan up to the limits set forth in the Internal Revenue Code. We may make additional discretionary contributions to the 401(k) plan as a percentage of total participant contributions, subject to established limits. Participants are fully vested in their contributions and any safe harbor matching contributions we make. We made safe harbor matching contributions of $736,000 , $551,000 and $458,000 during the years ended December 31, 2019 , 2018 and 2017 , respectively, which are included in general and administrative expense in the consolidated statements of operations. Income Taxes We account for income taxes under an asset and liability approach. Deferred income taxes reflect the impact of temporary differences between assets and liabilities recognized for financial reporting purposes and the amounts recognized for income tax reporting purposes, net operating loss, carryforwards, and other tax credits measured by applying currently enacted tax laws. A valuation allowance is provided when necessary to reduce deferred tax assets to an amount that is more likely than not to be realized. We determine whether a tax position taken in a filed tax return, planned to be taken in a future tax return or claim, or otherwise subject to interpretation, is more likely than not to be sustained upon examination, including resolution of any related appeals or litigation processes, based on the technical merits of the position, or prospectively approved when such approval may be sought in advance. We use a two-step approach to recognize and measure uncertain tax positions. The first step is to evaluate the tax position for recognition by determining if the available evidence indicates it is more likel

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Property and Equipment	Property and Equipment The following table presents the detail of property and equipment, net as recorded in the consolidated balance sheets: As of December 31, Useful Lives 2019 2018 (in years) (in thousands) Solar energy systems 35 $ 1,689,457 $ 1,311,458 Construction in progress 143,449 77,847 AROs 30 26,967 17,381 Information technology systems 3 28,320 17,380 Computers and equipment 3-5 1,499 1,251 Leasehold improvements 3-6 1,014 883 Furniture and fixtures 7 735 735 Vehicles 4 1,632 548 Other 5-6 146 52 Property and equipment, gross 1,893,219 1,427,535 Less: accumulated depreciation (148,159 ) (99,078 ) Property and equipment, net $ 1,745,060 $ 1,328,457 Solar Energy Systems. The amounts included in the above table for solar energy systems and substantially all the construction in progress relate to our customer contracts (including PPAs and leases). These assets had accumulated depreciation of $130.9 million and $87.6 million as of December 31, 2019 and 2018 , respectively. Capitalization of Interest Costs. We capitalized interest costs of $216,000 during the year ended December 31, 2017 , which were included in property and equipment. Due to the structure of our financing arrangements, interest no longer qualified for capitalization after March 2017.

Natural Disaster Losses

Natural Disaster Losses	12 Months Ended
	Dec. 31, 2019
Unusual or Infrequent Items, or Both [Abstract]
Natural Disaster Losses	Natural Disaster Losses We have insurance coverage related to property damage and business interruption. When a solar energy system is damaged by a natural disaster, we impair all or a portion of the net book value to operations and maintenance expense in the period for which the amount is probable and can be reasonably estimated. Insurance proceeds for property damage, up to the amount of impairment expense recorded for property damage, are estimated and recorded as a receivable (included in accounts receivable—other in the consolidated balance sheet) and a reduction to operations and maintenance expense when the receipt of the proceeds is deemed probable. Insurance proceeds for property damage that exceed the amount of impairment expense recorded and insurance proceeds related to business interruption are recorded when received, as a reduction to operations and maintenance expense. Costs incurred to repair or replace a solar energy system are capitalized (included in property and equipment, net in the consolidated balance sheet) and are classified as an investing cash outflow in the consolidated statement of cash flows. Insurance proceeds received for property damage are classified as an investing cash inflow in the consolidated statement of cash flows. Insurance proceeds received for business interruption are classified as an operating cash inflow in the consolidated statement of cash flows. Hurricane Harvey in Texas . In August 2017, Hurricane Harvey made landfall on the coast of Texas causing unprecedented flooding and significant damage to residences and businesses. During 2017, we incurred an insignificant amount of costs for Hurricane Harvey related to maintaining business continuity and assisting employees displaced from their homes. These costs were included in general and administrative expense in the consolidated statement of operations. Hurricane Maria in Puerto Rico . In September 2017, Hurricane Maria made landfall in Puerto Rico causing catastrophic wind and water damage to the island's infrastructure, residences and businesses. A majority of Puerto Rico was left without electrical power. In addition, other basic utility and infrastructure services (such as water, communications, ports and other transportation networks) were severely curtailed and the government imposed a mandatory curfew. Prior to the hurricane, we implemented certain business continuity measures. Although our critical business systems experienced minimal outages from the hurricane, our physical operations in Puerto Rico were significantly disrupted primarily due to the lack of electricity and communications and limited accessibility. Throughout 2017 and 2018, we completed assessments of solar energy systems in Puerto Rico and submitted requests to the insurance company for recoveries for damage to solar energy systems and business interruption. However, we did not complete all reasonable estimates until December 2018 due to the overall impact of the hurricane on Puerto Rico. Although our solar energy systems are distributed energy sources, most are dependent upon complementary grid power to operate and all are dependent upon cellular communication services for operations and monitoring and evaluation. The outage was the largest and longest in U.S. history. As such, many repairs and estimates of damages and lost customers lagged the restoration of these services. Given the loss of grid power and cellular communication and the fact that much of Puerto Rico was not navigable, assessment of our solar energy systems and status of our customers continued through the fourth quarter of 2018. We recorded adjustments based on the estimated amount of property damage as of December 31, 2017. The final settlement with the insurance company was completed and those funds were received in the fourth quarter of 2018. As of December 31, 2018, we received $9.8 million of insurance proceeds, of which $5.8 million represented recoveries for damage to solar energy systems and $4.0 million represented recoveries for business interruption. During 2017 and 2018, we reassessed the collectability of the receivables related to the solar energy systems in Puerto Rico and determined there were no significant write-offs or allowances needed. Wildfires in California . In October 2017 and November 2018, major wildfires burned throughout California and damaged several customers' homes and solar energy systems. These wildfires did not have a significant impact on our results of operations or financial position. The related impairments and insurance recoveries are included in the table below. Typhoon Yutu in Saipan . In October 2018, typhoon Yutu impacted Saipan causing massive wind and water damage to the island's infrastructure, residences and businesses. Several customer homes and solar energy systems were damaged; however, typhoon Yutu did not have a significant impact on our results of operations or financial position. The related impairments and insurance recoveries are included in the table below. As of December 31, 2019, substantially all solar energy systems damaged by a natural disaster that were deemed economical to repair have been repaired. The impact of the natural disaster losses as recorded in the consolidated statements of operations for the years ended December 31, 2019 , 2018 and 2017 is as follows: Year Ended 2019 2018 2017 (in thousands) Operations and maintenance expense: Impairment of solar energy systems due to natural disaster losses $ — $ 5,840 $ 6,745 Insurance proceeds received/expected to be received—property damage 54 (53 ) (5,922 ) Insurance proceeds received—business interruption — (2,693 ) (1,307 ) Other natural disaster-related charges — 1,679 65 General and administrative expense: Other natural disaster-related charges — 750 146 Total $ 54 $ 5,523 $ (273 )

Detail of Certain Balance Sheet

Detail of Certain Balance Sheet Captions	12 Months Ended
	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Detail of Certain Balance Sheet Captions	Detail of Certain Balance Sheet Captions The following table presents the detail of other current assets as recorded in the consolidated balance sheets: As of December 31, 2019 2018 (in thousands) Prepaid inventory $ 96,167 $ — Inventory 43,749 9,187 Current portion of customer notes receivable 13,758 7,601 Other prepaid assets 7,380 2,739 Current portion of other notes receivable 982 1,522 Deferred receivables 1,506 555 Restricted cash 10,474 5,190 Total $ 174,016 $ 26,794 The following table presents the detail of other current liabilities as recorded in the consolidated balance sheets: As of December 31, 2019 2018 (in thousands) Interest payable $ 14,680 $ 8,150 Current portion of performance guarantee obligations 4,067 2,580 Current portion of lease liability 561 871 Deferred revenue 2,086 1,593 Other 410 20 Total $ 21,804 $ 13,214

AROs

AROs	12 Months Ended
	Dec. 31, 2019
Asset Retirement Obligation Disclosure [Abstract]
AROs	AROs AROs consist primarily of costs to remove solar energy system assets and costs to restore the solar energy system sites to the original condition, which we estimate based on current market rates. For each solar energy system, we recognize the fair value of the ARO as a liability and capitalize that cost as part of the cost basis of the related solar energy system. The related assets are depreciated on a straight-line basis over 30 years , which is the estimated average time a solar energy system will be installed in a location before being removed, and the related liabilities are accreted to the full value over the same period of time. We revise our estimated future liabilities based on recent actual experiences, including third party cost estimates, average size of solar energy systems and inflation rates, which we evaluate at least annually. Changes in our estimated future liabilities are recorded as either a reduction or addition in the carrying amount of the remaining unamortized asset and the ARO and either decrease or increase our depreciation and accretion expense amounts prospectively. The following table presents the changes in AROs as recorded in other long-term liabilities in the consolidated balance sheets: As of December 31, 2019 2018 (in thousands) Balance at beginning of period $ 20,033 $ 15,347 Additional obligations incurred 4,641 3,607 Accretion expense 1,443 1,183 Change in estimate 4,983 — Other (47 ) (104 ) Balance at end of period $ 31,053 $ 20,033

Customer Notes Receivable

Customer Notes Receivable	12 Months Ended
	Dec. 31, 2019
Receivables [Abstract]
Customer Notes Receivable	Customer Notes Receivable We offer a loan program, under which the customer finances the purchase of a solar energy system or energy storage system through a solar service agreement, typically for a term of 10 or 25 years . As of December 31, 2019 , we recorded $311.7 million of notes receivable under the loan program, of which $13.8 million is included in other current assets and $298.0 million is included in customer notes receivable, net in the consolidated balance sheet. As of December 31, 2018 , we recorded $179.6 million of notes receivable under the loan program, of which $7.6 million is included in other current assets and $172.0 million is included in customer notes receivable, net in the consolidated balance sheet. As of December 31, 2019 and 2018 , we invested $37.1 million and $20.4 million , respectively, in loan solar energy systems and energy storage systems not yet placed in service, which is included in other assets in the consolidated balance sheets. The fair values of our customer notes receivable and the corresponding carrying amounts are as follows: As of December 31, 2019 As of December 31, 2018 Carrying Estimated Carrying Estimated (in thousands) Customer notes receivable $ 311,732 $ 314,222 $ 179,632 $ 179,990 Interest income from customer notes receivable is recorded in interest income in the consolidated statements of operations. For the years ended December 31, 2019 , 2018 and 2017 , interest income related to our customer notes receivable was $11.6 million , $6.1 million and $3.0 million , respectively.

Long-Term Debt

Long-Term Debt	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Long-Term Debt	Long-Term Debt Our subsidiaries with long-term debt include SEI, Sunnova Energy Corporation, Sunnova Asset Portfolio 4, LLC ("AP4"), AP6WII, HELI, LAPH, EZOP, TEPIH, TEPIIH, HELII, RAYSI, HELIII, TEPH and TEPINV. The following table presents the detail of long-term debt, net and long-term debt, net—affiliates as recorded in the consolidated balance sheets: Year Ended As of December 31, 2019 Year Ended As of December 31, 2018 Long-term Current Long-term Current (in thousands, except interest rates) SEI Convertible senior notes 7.75 % $ 55,000 $ — $ — $ — Debt discount, net (16,913 ) — — — Deferred financing costs, net (480 ) — — — Sunnova Energy Corporation Senior secured notes 10.02 % — — 14.89 % 40,000 — Convertible notes 13.34 % — — 12.20 % — 15,000 Notes payable 3.22 % — 2,428 — — Paid-in-kind — — 4,219 1,500 Deferred financing costs, net — — (38 ) — AP4 Secured term loan 5.61 % 86,369 6,109 5.25 % 101,026 3,036 Debt discount, net (452 ) — (202 ) — Deferred financing costs, net (196 ) — (418 ) — AP6WII Warehouse credit facility 10.01 % — — 8.47 % 54,603 — Deferred financing costs, net — — (309 ) — HELI Solar asset-backed notes 6.56 % 213,632 8,673 6.47 % 224,835 10,522 Debt discount, net (3,169 ) — (4,124 ) — Deferred financing costs, net (5,586 ) — (7,217 ) — LAPH Secured term loan 7.71 % 41,484 1,392 8.36 % 43,167 1,038 Debt discount, net (401 ) — (552 ) — Deferred financing costs, net (356 ) — (482 ) — EZOP Warehouse credit facility 6.60 % 121,400 — 9.68 % 58,200 — Debt discount, net (2,178 ) — — — TEPIH Secured term loan 25.17 % — — 6.55 % 107,239 3,356 Debt discount, net — — (62 ) — Deferred financing costs, net — — (4,892 ) — TEPIIH Revolving credit facility 6.36 % 234,650 — 8.41 % 57,552 — Debt discount, net (2,219 ) — (1,710 ) — Deferred financing costs, net — — (1,612 ) — HELII Solar asset-backed notes 5.77 % 241,309 13,005 5.60 % 253,687 9,013 Debt discount, net (49 ) — (55 ) — Deferred financing costs, net (5,873 ) — (6,425 ) — RAYSI Solar asset-backed notes 5.47 % 126,828 6,327 — — Debt discount, net (1,547 ) — — — Deferred financing costs, net (4,759 ) — — — HELIII Solar loan-backed notes 4.03 % 135,543 19,030 — — Debt discount, net (2,532 ) — — — Deferred financing costs, net (2,410 ) — — — TEPH Revolving credit facility 6.70 % 90,325 — — — Debt discount, net (645 ) — — — TEPINV Revolving credit facility 7.95 % 54,707 40,500 — — Debt discount, net (2,856 ) — — — Deferred financing costs, net (2,207 ) — — — Total $ 1,346,419 $ 97,464 $ 916,430 $ 43,465 Availability. As of December 31, 2019 , we had $88.3 million of available borrowing capacity under our various financing arrangements, consisting of $78.6 million under the EZOP warehouse credit facility and $9.7 million under the TEPH revolving credit facility. There was no available borrowing capacity under any of our other financing arrangements. As of December 31, 2019 , we were in compliance with all debt covenants under our financing arrangements. Weighted Average Effective Interest Rates. The weighted average effective interest rates disclosed in the table above are the weighted average stated interest rates for each debt instrument plus the effect on interest expense for other items classified as interest expense, such as the amortization of deferred financing costs, amortization of debt discounts and commitment fees on unused balances for the period of time the debt was outstanding during the indicated periods. SEI Convertible Senior Notes . In December 2019 , we issued convertible senior notes due January 2027 in an aggregate principal amount of $55.0 million to certain existing investors in a private placement. In addition, we granted the investors of the convertible senior notes an option, subject to our consent, to purchase up to an additional $20.0 million aggregate principal amount of convertible senior notes on the same terms and conditions, which such option will expire in March 2020 . The convertible senior notes bear interest at a rate of 7.75% per annum and is due quarterly. If we fail to satisfy certain registration requirements the convertible senior notes will bear additional interest at a rate of 0.25% per annum for each 90 -day period such requirements are not met, up to a maximum of 2.00% per annum. The convertible senior notes are convertible into our common stock at the option of the holders at any time prior to the close of business on the business day immediately preceding December 23, 2021 upon a change of control event. On or after December 23, 2021 until the close of business on the second scheduled trading day immediately preceding the maturity date, holders may, at their option, convert all or any portion of their convertible senior notes, in multiples of $1,000 principal amount. Upon conversion, we may satisfy our conversion obligation by paying and/or delivering, as the case may be, cash, shares of common stock, or a combination of cash and shares of common stock, at our option, subject to certain terms and conditions. The conversion rate for the convertible senior notes is 76.9231 shares of common stock per $1,000 principal amount of convertible senior notes, plus accrued and unpaid interest, which is equivalent to an initial conversion price (excluding interest) of approximately $13.00 per share of common stock. The conversion rate is subject to adjustment under certain circumstances in accordance with the terms of the convertible senior notes. On and after December 23, 2022 , we have the right to cause the conversion of the convertible senior notes if certain specified common stock price and volume conditions are met. We may, at our option, redeem for cash all or any portion of the convertible senior notes plus any accrued and unpaid interest to, but excluding, the redemption date at a redemption price equal to the following percentage of aggregate principal amount of convertible senior notes so redeemed: Period Percentage At any time prior to December 23, 2021 120% At any time on and after December 23, 2021 but prior to December 23, 2023 115% At any time on and after December 23, 2023 110% On and after September 23, 2024 , the holders of the convertible senior notes have the option to require us to repurchase their convertible senior notes for cash at a purchase price of 110% of the aggregate principal amount repurchased, plus accrued and unpaid interest to the date of repurchase. The convertible senior notes include customary covenants and set forth certain events of default after which the convertible senior notes may be declared immediately due and payable. For accounting purposes we separated the convertible senior notes into liability and equity components. As of December 31, 2019 , the carrying amount of the liability component for the convertible senior notes of approximately $37.6 million (net of an unamortized debt discount of $16.9 million and unamortized issuance costs of $480,000 ) was determined based on a discounted cash flow analysis and a binomial lattice model. The valuation required the use of Level 3 unobservable inputs and subjective assumptions, including but not limited to, the stock price volatility and bond yield. The use of alternative market assumptions and estimation methodologies could have had an effect on these estimates of fair value. As of December 31, 2019 , the carrying amount of the equity component for the convertible senior notes of approximately $14.0 million (net of unamortized issuance costs of $179,000 ), representing the conversion option, was determined by deducting the carrying amount of the liability components from the principal amount of the convertible senior notes. This difference between the principal amount of the convertible senior notes and the liability component represents the debt discount, presented as a reduction to the convertible senior notes in the consolidated balance sheet and is amortized to interest expense, net using the effective interest method over the remaining term of the convertible senior notes. The equity component of the convertible senior notes is included in additional paid-in-capital in the consolidated balance sheet and is not remeasured as long as it continues to meet the conditions for equity classification. Sunnova Energy Corporation Senior Secured Notes . In April 2017 , we issued senior secured notes due October 2018 in an aggregate principal amount of $80.0 million to certain existing investors. As part of the transaction, certain existing investors were required to commit to fund an additional $40.0 million to us by December 2017 in exchange for shares of Series A convertible preferred stock ("Preferred Stock Commitment"). As discussed below, we received funding for the Preferred Stock Commitment in October 2017. In addition, we were required to evidence the funding of additional subscriptions from existing or new investors for equity interests totaling $80.0 million , including the Preferred Stock Commitment that was already funded, by October 2018. The senior secured notes bore interest at an annual rate of 12.00% , of which 6.00% was payable in cash quarterly and the remaining 6.00% was payable in additional debt securities having the same terms, including maturity dates and interest rates, as the original debt securities, subject to certain conditions. This feature is commonly known as payment-in-kind and utilizing it effectively increases the principal note balance. The lenders of the senior secured notes were related parties and the related transactions have been classified as such in the consolidated balance sheets as of December 31, 2019 and 2018 and in the consolidated statements of operations and consolidated statements of cash flows for the years ended December 31, 2019 , 2018 and 2017 (see Note 12, Related-Party Transactions ). The terms under the senior secured notes contained certain covenants and restrictions, including the requirement that we maintain a minimum liquidity of $8.0 million at the end of each month and on a 30-day average for each month prior to the date certain affiliates of Energy Capital Partners ("ECP") had funded its portion of the Preferred Stock Commitment of $28.2 million , which ECP funded. In November 2017, the terms of the senior secured notes were amended to, among other things, allow for the issuance of Series B convertible preferred stock to certain of Sunnova Energy Corporation's affiliates. In May 2018, the terms of the senior secured notes were amended to extend the maturity date from October 2018 to January 2019. In January 2019, we amended the terms of the senior secured notes to, among other things, extend the maturity date from January 2019 to July 2019 . In April 2019, we further amended the terms of the senior secured notes to, among other things, (a) further extend the maturity date from July 2019 to March 2021, (b) decrease the interest rate from 12.00% per annum to 9.50% per annum, of which 4.75% was payable in cash quarterly and the remaining 4.75% was payable in additional debt securities (i.e. payment-in-kind) and (c) include a conversion feature . The April 2019 amendment resulted in a loss on extinguishment under GAAP of $10.6 million related to the difference between the net carrying value of the senior secured notes prior to the amendment and the fair value of the notes after the amendment . In connection with our IPO, we exercised our right to redeem all the senior secured notes for an aggregate amount of $57.1 million for cash . The aggregate redemption price included the principal amount outstanding of $56.2 million plus accrued and unpaid cash interest and pay-in-kind interest to the date of redemption. For accounting purposes, only the conversion feature was required to be bifurcated and measured at fair value; however, we elected to make a one-time, irrevocable election to utilize the fair value option allowed under ASC 825, Financial Instruments . Under the fair value option election, we recorded the entire hybrid instrument at fair value with changes in fair value recognized in other (income) expense in the consolidated statements of operations. The fair value election resulted in an additional loss of $730,000 due to the change in fair value from April 2019 to July 2019. Sunnova Energy Corporation Convertible Notes . In March 2018, we issued a convertible note for $15.0 million to certain of our existing investors, which was subordinated to the senior secured notes, with a maturity date of the earlier of (a) the repayment of the Sunnova senior secured notes or (b) May 2019 (the "2018 Note"). In January 2019, we amended the terms of the 2018 Note to, among other things, extend the maturity date to the earlier of (a) the repayment of the senior secured notes or (b) December 2019 . The 2018 Note bore interest at an annual rate of 12.00% , which was only payable by increasing the outstanding principal balance of the 2018 Note quarterly until maturity. Under the terms of the 2018 Note, we could not make cash payments for interest or principal on the 2018 Note until the senior secured notes had been repaid in full. The 2018 Note allowed for the holders to convert the outstanding principal balance (including accrued paid-in-kind interest) into Series A convertible preferred stock at a rate equal to the lesser of $5.3246735 per share (adjusted for subsequent stock splits, combinations, recapitalizations or the like affecting the Series A convertible preferred stock) or the lowest purchase price per share of Series A convertible preferred stock issued after the date of the 2018 Note. In June 2019 , we issued a convertible note for $15.0 million to certain of our existing investors, which was subordinated to the senior secured notes, with a maturity date of the earlier of (a) the repayment of our senior secured notes or (b) September 2021 (the "2019 Note"). The 2019 Note bore interest at an annual rate of 12.00% , which was only payable by increasing the outstanding principal balance of the 2019 Note quarterly until maturity. Under the terms of the 2019 Note, we were not permitted to make cash payments for interest or principal on the 2019 Note until the senior secured notes had been repaid in full. The 2019 Note allowed, if a majority of holders had elected, the conversion of the outstanding principal balance (including accrued paid-in-kind interest) into Series C convertible preferred stock at a rate equal to the lesser of $5.80 per share (adjusted for subsequent stock splits, combinations, recapitalizations or the like affecting convertible preferred stock) or the lowest purchase price per share of Series C convertible preferred stock issued after the date of the 2019 Note. In connection with our IPO, holders of the 2018 Note converted the principal amount of the 2018 Note plus any accrued and unpaid interest as of the date of conversion into 3,319,312 shares (or 1,422,767 shares as adjusted for the Reverse Stock Split) of Series A convertible preferred stock, which in turn converted into 1,422,767 shares of common stock. In addition, holders of the 2019 Note converted the principal amount of the 2019 Note plus any accrued and unpaid interest as of the date of conversion into 2,613,818 shares (or 1,120,360 shares as adjusted for the Reverse Stock Split) of Series C convertible preferred stock, which in turn converted into 1,120,360 shares of common stock. Sunnova Energy Corporation Notes Payable . In May 2019 , we entered into an arrangement to finance $1.9 million in property insurance premiums at an annual interest rate of 5.50% over ten months . In July 2019 , we entered into an arrangement to finance $4.7 million in directors and officers insurance premiums at an annual interest rate of 4.94% over eight months . AP4 Debt . In July 2014, we entered into a collateral-based financing agreement with Texas Capital Bank, as administrative agent, and the lenders party thereto, to obtain funding for solar energy systems, working capital and general and administrative expenses of Sunnova Energy Corporation and AP4. The initial aggregate principal amount of the commitments under the AP4 financing agreement was $90.0 million , which was increased to $110.0 million in October 2015 and then reduced to $107.1 million in December 2017 . Borrowings under the AP4 financing agreement are secured by the assets of AP4, which include certain solar energy systems and the related solar service agreements, accounts receivable and note receivable. The loans under the AP4 financing agreement bear interest at an annual rate of either LIBOR plus 3.00% or a base rate (defined as, for any day, a rate of interest per annum equal to the highest of (a) the prime rate for such day; (b) the sum of the federal funds rate for such day plus 0.50% ; and (c) adjusted LIBOR for such day plus 1.00% ) plus 2.00% . In addition, through December 2016, the AP4 debt accrued a commitment fee at a rate equal to 0.50% per year of the daily unused amount of the commitment. In December 2016, the loans converted to an amortizing term loan and began amortizing quarterly based on a modified mortgage style amortization schedule. The terms under the AP4 financing agreement contain certain covenants and restrictions, including a ratio of consolidated EBITDA (as defined in the AP4 financing agreement) to debt service (as defined in the AP4 financing agreement) that may not be less than 1.25 to 1.00 for any four-quarter period ending as of the end of any fiscal quarter. Furthermore, the borrowers are permitted to pay distributions so long as after giving effect thereto, the debt service coverage ratio is at least 1.0 to 1.0 . In March 2017 , the AP4 financing agreement was amended to, among other things, extend the maturity date from July 2019 to July 2020 . In December 2017, the AP4 financing agreement was amended to, among other things, admit into the collateral pool and borrow against certain assets previously financed under another subsidiary's financing agreement, the proceeds of which were used to repay a substantial portion of the aggregate outstanding principal amount under the subsidiary's financing agreement. In December 2018 , the AP4 financing agreement was amended to, among other things, extend the start date of required excess cash flow payments from January 2019 to June 2019 and add a minimum net worth requirement. As of March 31, 2019, AP4 was not in compliance with the debt covenant regarding the ratio of consolidated EBITDA to debt service, which is an event of default. In April 2019, AP4 exercised its right to an equity cure, which allowed Sunnova Energy Corporation to contribute approximately $106,000 to AP4 and allowed AP4 to add such amount to consolidated EBITDA for purposes of recalculating the ratio as of March 31, 2019. Subsequent to the equity cure, AP4 is in compliance with the debt covenants under the AP4 financing agreement. In June 2019 , we amended the AP4 financing agreement to, among other things, (a) extend the maturity date from July 2020 to January 2021 , (b) decrease the applicable margin for LIBOR loans to 2.50% and (c) change the debt covenant regarding the ratio of consolidated EBITDA to debt service to be calculated based on collections from customers and other cash receipts and disbursements (instead of consolidated EBITDA). In connection with this amendment we repaid $5.0 million of outstanding borrowings under this facility. In August 2019 , AP4 conveyed its ownership interest in Sunnova Lease Vehicle 3-HI, LLC to Sunnova Energy Corporation and the security interest on the assets of Sunnova Lease Vehicle 3-HI, LLC that were previously collateral securing the borrowings under the AP4 financing agreement was released. See Note 18, Subsequent Events . AP6WII Debt . In April 2016, AP6WII, a special purpose entity, entered into a secured revolving warehouse credit facility with Goldman Sachs Bank USA. The warehouse credit facility allowed for the pooling and transfer of eligible solar energy systems and related asset receivables on a non-recourse basis subject to certain limited exceptions. The assets and cash flows of AP6WII were not available to satisfy our obligations or any other affiliate of AP6WII and AP6WII was not liable for any of our obligations or any other affiliate of AP6WII. The creditors of AP6WII had no recourse to our other assets except as expressly set forth in the credit agreement. The aggregate principal amount of commitments under the AP6WII warehouse credit facility was $175.0 million , which could be increased at AP6WII's request and the committed lender's discretion. The proceeds of the loans under the warehouse credit facility were available to purchase or otherwise acquire solar energy systems and certain related solar energy system assets (which we originated) directly from Sunnova Asset Portfolio 6, LLC ("AP6"), a wholly-owned subsidiary of Sunnova Asset Portfolio 6 Holdings, LLC ("AP6H") and sole member of AP6WII, pursuant to a sale and contribution agreement, fund certain reserve accounts that were required to be maintained by AP6WII in accordance with the credit agreement governing the warehouse credit facility, purchase interest rate swaps and swaptions in connection with borrowings and pay fees and expenses incurred in connection with the warehouse credit facility. The amount available for borrowings at any one time under the warehouse credit facility was limited to a borrowing base amount determined at each borrowing and calculated based on the aggregate discounted present value of remaining payments owed to AP6WII in respect of the solar energy systems transferred to AP6WII. The AP6WII credit facility had a maturity date of April 2020 . Interest on the borrowings under the warehouse credit facility was due monthly. During the commitment availability period, borrowings under the AP6WII warehouse credit facility bore interest at an annual rate equal to LIBOR or, if such rate was unavailable, a base rate, plus (a) the ratio of discounted cash flows for all eligible solar energy systems other than those subject to the loan program to the discounted cash flows for all eligible solar energy systems multiplied by 5.00% per year plus (b) the ratio of discounted cash flows for eligible solar energy systems subject to the loan program to the discounted cash flows for all eligible solar energy systems multiplied by 4.25% per year. After the availability period, interest accrued at an annual rate equal to LIBOR or, if such rate was unavailable, a base rate, plus (a) the ratio of discounted cash flows for all eligible solar energy systems other than those subject to the loan program to the discounted cash flows for all eligible solar energy systems multiplied by 5.50% per year plus (b) the ratio of discounted cash flows for eligible solar energy systems subject to the loan program to the discounted cash flows for all eligible solar energy systems multiplied by 4.75% per year. The warehouse credit facility required AP6WII to pay a fee based on the daily unused portion of the commitments under the warehouse credit facility. Since May 2018, the warehouse credit facility required AP6WII to pay an underutilization fee based on the prior twelve month's commitments meeting certain thresholds under the warehouse credit facility. The credit agreement was secured by a first priority security interest in all of AP6WII's assets. Revenues from the solar energy systems were deposited into accounts established pursuant to the warehouse credit facility and applied in accordance with a cash waterfall in the manner specified in the warehouse credit facility. AP6WII was also required to maintain a liquidity reserve account and an inverter replacement reserve account for the benefit of the lenders under the warehouse credit facility, each of which must remain funded at all times to the levels specified in the credit agreement (see Note 2, Significant Accounting Policies ). In connection with the AP6WII warehouse credit facility, certain of our affiliates received a fee for managing and servicing the solar energy systems pursuant to management and servicing agreements. In addition, Sunnova Energy Corporation had guaranteed (a) the manager's obligations to manage the solar energy systems pursuant to the management agreement, (b) the servicer's obligations to service the solar energy systems pursuant to the servicing agreement, (c) Sunnova Intermediate Holdings, LLC's, AP6H's and AP6's obligations to repurchase or substitute certain ineligible solar energy systems eventually sold to AP6WII pursuant to the sale and contribution agreement and (d) certain indemnification obligations related to our affiliates in connection with the AP6WII warehouse credit facility, but did not provide a general guarantee of the creditworthiness of the assets of AP6WII pledged as the collateral for the warehouse credit facility. Under the limited guarantee, Sunnova Energy Corporation was subject to certain financial covenants regarding tangible net worth and unrestricted liquidity (including unrestricted cash and availability under other debt and equity financing arrangements). In April 2017, the AP6WII warehouse credit facility was amended to, among other things, extend the availability period from April 2017 to April 2019 , extend the maturity date from April 2018 to April 2020 and change the borrowing base and interest amounts to be calculated separately for PPAs and leases versus solar energy systems subject to the loan program. In June 2019, we fully repaid the aggregate outstanding principal amount and terminated the AP6WII warehouse credit facility. HELI Debt and Securitization . In April 2017 , we pooled and transferred eligible solar energy systems and the related asset receivables into HELI, a special purpose entity, that issued $191.8 million in aggregate principal amount of Series 2017-1 Class A solar asset-backed notes, $18.0 million in aggregate principal amount of Series 2017-1 Class B solar asset-backed notes and $45.0 million in aggregate principal amount of Series 2017-1 Class C solar asset-backed notes (collectively, the "Notes") with a maturity date of September 2049 . The Notes were issued at a discount of 0.05% for Class A, 9.28% for Class B and 8.65% for Class C and bear interest at an annual rate equal to 4.94% , 6.00% and 8.00% , respectively. As of December 31, 2019 , these solar energy systems had a carrying value of $296.8 million and are included in property and equipment, net in the consolidated balance sheet. The cash flows generated by these solar energy systems are used to service the semi-annual principal and interest payments on the Notes and satisfy HELI's expenses, and any remaining cash can be distributed to Helios Depositor, LLC, HELI's sole member. In connection with the Notes, certain of our affiliates receive a fee for managing and servicing the solar energy systems pursuant to management and servicing agreements. In addition, Sunnova Energy Corporation has guaranteed (a) the manager's obligations to manage the solar energy systems pursuant to the management agreement, (b) the servicer's obligations to service the solar energy systems pursuant to the servicing agreement and (c) Sunnova Asset Portfolio 5, LLC's obligations to repurchase or substitute certain ineligible solar energy systems eventually sold to HELI pursuant to the sale and contribution agreement. HELI is also required to maintain a liquidity reserve account and an inverter replacement reserve account for the benefit of the lenders under the Notes, each of which must remain funded at all times to the levels specified in the Notes (see Note 2, Significant Accounting Policies ). The creditors of HELI have no recourse to our other assets except as expressly set forth in the Notes. LAPH Debt and Securitization . In April 2017 , LAPH and its wholly-owned subsidiaries Sunnova LAP I, LLC and Sunnova LAP II, LLC, entered into a term loan agreement with Credit Suisse AG, New York Branch, as administrative agent, and the lenders party thereto, for an initial aggregate committed principal amount of $260.0 million with a maturity date of December 2018 , which was amended (see below). The proceeds of the loans were available to purchase or otherwise acquire solar energy systems (which we originated) directly from Sunnova Asset Portfolio 7 Holdings, LLC ("AP7H"), the sole member of LAPH, pursuant to a sale and contribution agreement, fund certain reserve accounts that are required to be maintained by the borrowers in accordance with the loan agreement and pay fees and expenses incurred in connection with the loan agreement. The amount available for borrowings at any one time under the loan agreement was limited to a borrowing base amount determined at each borrowing and calculated based on the aggregate discounted present value of remaining payments owed to LAPH and its wholly-owned subsidiaries in respect of the solar energy systems transferred to LAPH and its wholly-owned subsidiaries. Interest on the borrowings under the LAPH loan agreement was due monthly; however, it was amended to be due quarterly in November 2018 (see below). Class A advances under the LAPH loan agreement initially bore interest at an annual rate equal to the weighted-average cost to the lender of any commercial paper (to the extent the lender funds an advance by issuing commercial paper) plus 3.30% . Class B advances bore interest at an annual rate equal to 11.00% . The loan agreement requires the borrowers to pay a fee based on the daily unused portion of the commitments under the loan agreement. Revenues from the solar energy systems will be deposited into accounts established pursuant to the loan agreement and applied in accordance with a cash waterfall in the manner specified in the loan agreement. The borrowers are also required to maintain a liquidity reserve account and an inverter replacement reserve account for the benefit of the lenders under the loan agreement, each of which must remain funded at all times to the levels specified in the loan agreement (see Note 2, Significant Accounting Policies ). In connection with the LAPH loan agreement, certain of our affiliates receive a fee for managing and servicing the solar energy systems pursuant to management and servicing agreements. In addition, Sunnova Energy Corporation has guaranteed (a) the manager's obligations to manage the solar energy systems pursuant to the management agreement, (b) the servicer's obligations to service the solar energy systems pursuant to the servicing agreement, (c) AP7H's obligations to repurchase or substitute certain ineligible solar energy systems sold to LAPH and its wholly-owned subsidiaries pursuant to certain sale and contribution agreements and (d) certain indemnification obligations related to its affiliates in connection with the LAPH loan agreement, but does not provide a general guarantee of the creditworthiness of the assets of LAPH and its wholly-owned subsidiaries pledged as the collateral for the loan agreement. Under the limited guarantee, Sunnova Energy Corporation is subject to certain financial covenants regarding tangible net worth, working capital and restrictions on the use of proceeds from the loan agreement. In April 2018 , the LAPH loan agreement was amended to, among other things, extend the maturity date from December 2018 to May 2019 . In November 2018 , the LAPH loan agreement was amended to, among other things, decrease the maximum commitment amount of Class A advances to $44.2 million and of Class B advances to $0 , extend the maturity date to November 2022 , change the interest on Class A advances to an annual rate equal to LIBOR plus 4.50% and change the interest collection period from monthly to quarterly. EZOP Debt and Securitization . In April 2017 , EZOP, a special purpose entity, entered into a secured revolving warehouse credit facility with Credit Suisse AG, New York Branch, as administrative agent, and the lenders party thereto, for an aggregate committed amount of $100.0 million with a maturity date of April 2019 . The aggregate committed amount was reduced to $70.0 million in August 2017 and in March 2019 we further amended the EZOP warehouse credit facility to, among other things, extend the maturity date from April 2019 to November 2022 and increase the aggregate committed amount to $200.0 million . The warehouse credit facility allows for the pooling and transfer of eligible loans on a non-recourse basis subject to certain limited exceptions. The proceeds of the loans under the warehouse credit facility are available to purchase or otherwise acquire loans (which we originated) directly from AP7H pursuant to a sale and

Derivative Instruments

Derivative Instruments	12 Months Ended
	Dec. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	Derivative Instruments Interest Rate Swaps on AP4 Debt . During the year ended December 31, 2018 , AP4 unwound all outstanding interest rate swaps with an aggregate notional amount of $105.2 million and received cash of $666,000 . AP4 subsequently entered into an interest rate swap with a notional amount of $105.2 million . In April 2018 , the notional amount of the interest rate swap began decreasing to match AP4's estimated quarterly principal payments on the debt. See Note 18, Subsequent Events . Interest Rate Swaps on AP6WII Debt. During the years ended December 31, 2019 and 2018 , AP6WII entered into interest rate swaps for an aggregate notional amount of $103.5 million and $63.6 million , respectively, to economically hedge its exposure to the variable interest rates on a portion of the outstanding AP6WII debt. During the year ended December 31, 2019 , the aggregate outstanding principal amount under the AP6WII warehouse credit facility was fully repaid, AP6WII unwound interest rate swaps with an aggregate notional amount of $84.1 million and recorded a realized loss of $8.7 million . During the year ended December 31, 2018 , AP6WII unwound interest rate swaps with an aggregate notional amount of $101.4 million and recorded a realized gain of $5.7 million . No collateral was posted for the interest rate swaps as they are secured under the AP6WII warehouse credit facility. Interest Rate Swaps on LAPH Debt. During the year ended December 31, 2018 , LAPH entered into interest rate swaps for an aggregate notional amount of $44.2 million to economically hedge its exposure to the variable interest rates on a portion of the outstanding LAPH debt. In January 2019 , the notional amount of the interest rate swaps began decreasing to match LAPH's estimated quarterly principal payments on the debt. During the year ended December 31, 2018 , LAPH unwound an interest rate swap with a notional amount of $224.2 million and recorded a realized gain of $11.5 million . No collateral was posted for the interest rate swap as it is secured under the LAPH loan agreement. Interest Rate Swaps on EZOP Debt. During the years ended December 31, 2019 and 2018 , EZOP entered into interest rate swaps for an aggregate notional amount of $255.8 million and $102.6 million , respectively, to economically hedge its exposure to the variable interest rates on a portion of the outstanding EZOP debt. In March 2018, the notional amount of the interest rate swaps began decreasing to match EZOP's estimated monthly principal payments on the debt. During the year ended December 31, 2019 , EZOP unwound interest rate swaps with a notional amount of $264.6 million and recorded a realized gain of $81,000 . No collateral was posted for the interest rate swap as it is secured under the EZOP warehouse credit facility. Interest Rate Swaps on TEPIH Debt. During the year ended December 31, 2018 , TEPIH entered into interest rate swaps for an aggregate notional amount of $41.7 million to economically hedge its exposure to the variable interest rates on a portion of the outstanding TEPIH debt. In January 2018 , the notional amount of the interest rate swaps began decreasing to match TEPIH's estimated quarterly principal payments on the debt. No collateral was posted for the interest rate swaps as they are secured under the TEPIH loan agreement. During the year ended December 31, 2019 , the aggregate outstanding principal amount under the TEPIH loan agreement was fully repaid, TEPIH unwound interest rate swaps with an aggregate notional amount of $102.9 million and recorded a realized loss of $3.5 million . Interest Rate Swaps on TEPIIH Debt. During the years ended December 31, 2019 and 2018 , TEPIIH entered into interest rate swaps for an aggregate notional amount of $171.2 million and $54.7 million , respectively, to economically hedge its exposure to the variable interest rates on a portion of the outstanding TEPIIH debt. Beginning in October 2020 , the notional amount of the interest rate swaps decreases to match TEPIIH's estimated quarterly principal payments on the debt. No collateral was posted for the interest rate swaps as they are secured under the TEPIIH revolving credit facility. See Note 18, Subsequent Events . Interest Rate Swaps on TEPH Debt. During the year ended December 31, 2019 , TEPH entered into interest rate swaps for an aggregate notional amount of $103.1 million to economically hedge its exposure to the variable interest rates on a portion of the outstanding TEPH debt. Beginning in July 2022 , the notional amount of the interest rate swap decreases to match TEPH's estimated quarterly principal payments on the debt. No collateral was posted for the interest rate swaps as they are secured under the TEPH revolving credit facility. The following table presents a summary of the outstanding derivative instruments: As of December 31, 2019 2018 Effective Termination Fixed Aggregate Effective Termination Fixed Aggregate (in thousands, except interest rates) AP4 March 2018 July 2020 2.338% $ 99,762 March 2018 July 2020 2.338% $ 102,921 AP6WII —% — April 2019 April 2019 - 2.402% - 72,025 LAPH November 2018 October 2036 3.409% 43,298 November 2018 October 2036 3.409% 44,205 EZOP June 2019 - July 2029 - 1.631% - 100,083 March 2018 April 2019 - 1.900% - 55,290 TEPIH —% — June 2017 - April 2033 - 2.350% - 99,536 TEPIIH September 2018 July 2031 - 1.909% - 225,845 September 2018 - July 2031 - 2.995% - 54,675 TEPH September 2019 January 2023 1.620% - 55,115 —% — Total $ 524,103 $ 428,652 The following table presents the fair value of the interest rate swaps as recorded in the consolidated balance sheets: As of December 31, 2019 2018 (in thousands) Other assets $ 360 $ 270 Other current liabilities (397 ) — Other long-term liabilities (27,092 ) (8,161 ) Total, net $ (27,129 ) $ (7,891 ) We did not designate the interest rate swaps and swaptions as hedging instruments for accounting purposes. As a result, we recognize changes in fair value immediately in interest expense, net. The following table presents the impact of the interest rate swaps and swaptions as recorded in the consolidated statements of operations: Year Ended 2019 2018 2017 (in thousands) Realized (gain) loss $ 13,195 $ (17,004 ) $ 3,295 Unrealized loss 19,237 6,100 5,944 Total $ 32,432 $ (10,904 ) $ 9,239

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Our effective income tax rate is 0% for the years ended December 31, 2019 , 2018 and 2017 . Total income tax differs from the amounts computed by applying the statutory income tax rate to loss before income tax primarily as a result of our valuation allowance. The sources of these differences are as follows: Year Ended 2019 2018 2017 (in thousands) Loss before income tax $ (133,434 ) $ (68,409 ) $ (90,182 ) Statutory federal tax rate 21 % 21 % 35 % Tax benefit computed at statutory rate (28,021 ) (14,366 ) (31,564 ) State income tax, net of federal benefit (8,344 ) (4,308 ) (3,406 ) Adjustments from permanent differences: Enactment of the Tax Cuts and Jobs Act — — 6,118 Redeemable noncontrolling interests (2,293 ) (1,226 ) — ITC recapture 296 989 — Other 852 234 1,185 Increase in valuation allowance, net 37,510 18,677 27,667 Total income tax $ — $ — $ — State, federal and foreign income taxes are $0 for the years ended December 31, 2019 , 2018 and 2017 . The tax effects of temporary differences that give rise to significant portions of the deferred tax assets (liabilities) are as follows: As of December 31, 2019 2018 (tax effected, in thousands) Federal net operating loss carryforward $ 169,379 $ 137,810 State net operating loss carryforward 49,565 38,659 ITC carryforward 246,828 226,378 Federal unused interest deduction carryforward 22,559 10,202 Investment in certain financing arrangements 36,999 16,374 Other deferred tax assets 20,801 11,531 Deferred tax assets 546,131 440,954 Fixed asset basis difference (235,510 ) (188,087 ) Investment in certain financing arrangements (22,826 ) (5,391 ) Other deferred tax liabilities (2,819 ) (874 ) Deferred tax liabilities (261,155 ) (194,352 ) Valuation allowance (284,976 ) (246,602 ) Net deferred tax asset $ — $ — Enactment of the Tax Cuts and Jobs Act . In December 2017, the U.S. enacted tax legislation commonly known as the Tax Cuts and Jobs Act. This law significantly changed U.S. corporate income tax laws by, among other things, reducing the U.S. federal corporate income tax rate from a highest marginal rate of 35% to a flat rate of 21% beginning in 2018. During the year ended December 31, 2017 , we recognized income tax expense of $6.1 million for the revaluation of the net deferred tax asset based on a U.S. federal corporate income tax rate of 21% , which was fully offset by a reduction in the net deferred tax asset valuation allowance. A full valuation allowance of $285.0 million and $246.6 million was recorded against our net deferred tax assets as of December 31, 2019 and 2018 , respectively. We believe it is not more likely than not that future taxable income and the reversal of deferred tax liabilities will be sufficient to realize our net deferred tax assets. Our estimated federal tax net operating loss carryforward as of December 31, 2019 is approximately $806.6 million , which will begin to expire in 2032 if not utilized. We also generated $20.5 million of Section 48(a) ITCs in 2019 for a net $246.8 million through December 31, 2019 , which will begin to expire in 2033 if not utilized. We assessed whether we had any significant uncertain tax positions taken in a filed tax return, planned to be taken in a future tax return or claim, or otherwise subject to interpretation and determined there were none not more likely than not to be sustained upon examination, including resolution of any related appeals or litigation processes, based on the technical merits of the position, or prospectively approved when such approval may be sought in advance. Accordingly, we recorded no reserve for uncertain tax positions. Should a provision for any interest or penalties relative to unrecognized tax benefits be necessary, it is our policy to accrue for such in our income tax accounts. There were no such accruals as of December 31, 2019 and 2018 and we do not expect a significant change in gross unrecognized tax benefits in the next twelve months. Our tax years 2012 through 2018 remain subject to examination by the IRS and the states and territories in which we operate.

Details of Certain Subsidiary A

Details of Certain Subsidiary Assets and Liabilities	12 Months Ended
	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Details of Certain Subsidiary Assets and Liabilities	Detail of Certain Subsidiary Assets and Liabilities As discussed in Note 8, Long-Term Debt , in April 2017, LAPH and EZOP entered into a loan agreement and warehouse credit facility, respectively, that allows for the pooling and transfer of eligible solar energy systems and related asset receivables on a basis that is generally non-recourse. Under the agreements, the loan proceeds of LAPH and EZOP are available to purchase or otherwise acquire solar energy systems and certain related assets directly from AP7H pursuant to a sale and contribution agreement. In September 2019, TEPH entered into a loan agreement that allows TEPH to borrow on the aggregate value of solar assets owned by subsidiaries of TEPH pursuant to a pledge agreement. The following table presents the detail of assets and liabilities of certain subsidiaries as recorded in the consolidated balance sheet: As of December 31, 2019 Sunnova LAPH EZOP TEPH (in thousands) Assets Current assets: Cash $ 82,788 $ 1,323 $ 2,143 $ 14,672 Accounts receivable—trade, net 10,672 497 367 295 Accounts receivable, net—affiliates — — 78 — Accounts receivable—other 6,147 — — 4 Other current assets 174,016 172 5,314 47,388 Total current assets 273,623 1,992 7,902 62,359 Property and equipment, net 1,745,060 54,558 — 168,348 Customer notes receivable, net 297,975 — 125,950 — Other assets 169,712 1,815 6,629 5,564 Total assets $ 2,486,370 $ 58,365 $ 140,481 $ 236,271 Liabilities Current liabilities: Accounts payable $ 36,190 $ 14 $ 16 $ 247 Accounts payable, net—affiliates — 1,220 — 80,298 Accrued expenses 39,544 87 44 282 Current portion of long-term debt 97,464 1,392 — — Other current liabilities 21,720 818 165 697 Total current liabilities 194,918 3,531 225 81,524 Long-term debt, net 1,308,812 40,727 119,222 89,680 Other long-term liabilities 127,406 7,606 27,796 1,442 Total liabilities $ 1,631,136 $ 51,864 $ 147,243 $ 172,646

Related-Party Transactions

Related-Party Transactions	12 Months Ended
	Dec. 31, 2019
Related Party Transactions [Abstract]
Related-Party Transactions	Related-Party Transactions Sunnova Debt . Certain of our affiliates who have representatives on our Board were holders of the senior secured notes and the convertible notes. In connection with our IPO, we redeemed the senior secured notes for cash and the holders of the convertible notes converted the principal amount plus accrued and unpaid interest into shares of common stock. See Note 8, Long-Term Debt . We have classified these related transactions as such in the consolidated balance sheet as of December 31, 2018 and in the consolidated statements of operations and consolidated statements of cash flows for the years ended December 31, 2019 , 2018 and 2017 . Promissory Notes . In March 2018 , we entered into a bonus agreement with an executive officer providing that each year beginning in January 2019 , one-fourth of the outstanding loan balance (and related accrued and unpaid interest) under the promissory notes executed by that officer and an entity controlled by that officer, in favor of Sunnova Energy Corporation, in combined aggregate principal amounts totaling $1.7 million (the "Officer Notes"), was to be forgiven provided that officer remained employed through the applicable forgiveness date, such that the full amount of the Officer Notes would be forgiven as of January 2022 . In January 2019 , one-fourth of the balance of the Officer Notes was forgiven. In June 2019 , as additional bonus compensation, the remaining principal and interest in the amount of $1.4 million associated with the Officer Notes was forgiven and Sunnova Energy Corporation agreed to pay the officer a bonus to reimburse the officer for the expected tax liability associated with such forgiveness of $892,000 , which was paid in August 2019 .

Redeemable Noncontrolling Inter

Redeemable Noncontrolling Interests	12 Months Ended
	Dec. 31, 2019
Noncontrolling Interest [Abstract]
Redeemable Noncontrolling Interests	Redeemable Noncontrolling Interests In February 2017, we formed TEPI, a subsidiary of Sunnova TEP I Manager, LLC, which is the Class B member of TEPI. In March 2017, we admitted a tax equity investor as the Class A member of TEPI. The Class A member of TEPI made an initial capital commitment of $80.0 million and increased this commitment to $91.1 million in November 2017 and to $97.5 million in December 2017. In October 2017, we formed TEPII and in December 2017, we formed TEPIIB, each a subsidiary of Sunnova TEP II Manager, LLC, which is the Class B member of TEPII and TEPIIB. In December 2017, we admitted a tax equity investor as the Class A member of TEPII and TEPIIB. The Class A member of TEPII and TEPIIB made an initial capital commitment of $30.0 million and $40.0 million to TEPII and TEPIIB, respectively, and increased this commitment to $57.0 million for TEPIIB in May 2018. In January 2019, we admitted tax equity investors as the Class A members of TEPIII, a subsidiary of Sunnova TEP III Manager, LLC which is the Class B member of TEPIII. The Class A members of TEPIII made a total capital commitment of $50.0 million . In June 2019, the Class A member of TEPII increased its commitment from $30.0 million to $45.0 million . In August 2019 , we admitted a tax equity investor as the Class A member of TEPIVA, a subsidiary of Sunnova TEP IV-A Manager, LLC, which is the Class B member of TEPIVA. The Class A member of TEPIVA made a total capital commitment of $75.0 million . In December 2019 , we admitted a tax equity investor as the Class A member of TEPIVB, a subsidiary of Sunnova TEP IV-B Manager, LLC, which is the Class B member of TEPIVB. The Class A member of TEPIVB made a total capital commitment of $50.0 million . The purpose of the tax equity entities is to own and operate a portfolio of residential solar energy systems and energy storage systems. The terms of the tax equity entities' operating agreements contain allocations of income (loss), Section 48(a) ITCs and cash distributions that vary over time and adjust between the members on an agreed date (referred to as the flip date). The operating agreements specify either a calendar flip date or an internal rate of return ("IRR") flip date. The calendar flip date is based on the passage of a fixed period of time that generally corresponds to the expiration of the recapture period associated with Section 48(a) ITCs or a year thereafter. The IRR flip date is the date on which the tax equity investor has achieved a contractual rate of return. From inception through the flip date, the Class A members' allocation of income (loss) and Section 48(a) ITCs is generally 93% to 99% and the Class B members' allocation of income (loss) and Section 48(a) ITCs is generally 1% to 7% . After the related flip date, the Class A members' allocation of income (loss) will decrease to a range of 1% to 7% and the Class B members' allocation of income (loss) will increase to a range of 93% to 99% . The redeemable noncontrolling interests are comprised of Class A units, which represent the tax equity investors' interest in the tax equity entities, and are classified between liabilities and equity in the consolidated balance sheets. Both the Class A members and Class B members have written call options to allow either member to redeem the other member's interest in the tax equity entities upon the occurrence of certain contingent events, such as bankruptcy, dissolution/liquidation and forced divestitures of the tax equity entities. Additionally, the Class B members have the option to purchase all Class A units, which is typically exercisable at any time during the nine-month period commencing upon the applicable flip date, and also have the contingent obligation to purchase all Class A units if the Class A members exercise their right to withdraw, which is typically exercisable at any time during the nine-month period commencing upon the applicable flip date. The carrying values of the redeemable noncontrolling interests were equal to the redemption values as of December 31, 2019 and 2018 , with the exception of TEPIVA and TEPIVB, for which we are not required to carry a redemption value. Guarantees . We are contractually obligated to make certain Class A members whole for losses they may suffer in certain limited circumstances resulting from the disallowance or recapture of Section 48(a) ITCs. We have concluded the likelihood of a significant recapture event is remote and consequently have not recorded a liability for any potential recapture exposure. The maximum potential future payments we could be required to make under this obligation would depend on the IRS successfully asserting upon audit the fair market values of the solar energy systems sold or transferred to the tax equity entities as determined by us exceed the allowable basis for the systems for purposes of claiming Section 48(a) ITCs. The fair market values of the solar energy systems and related Section 48(a) ITCs are determined and the Section 48(a) ITCs are allocated to the Class A members in accordance with the tax equity entities' operating agreements. Due to uncertainties associated with estimating the timing and amounts of distributions, the likelihood of an event that may trigger repayment, forfeiture or recapture of Section 48(a) ITCs to such Class A members, and the fact that we cannot determine how the IRS will evaluate system values used in claiming Section 48(a) ITCs, we cannot determine the potential maximum future payments that are required under these guarantees. From time to time, we incur non-performance fees, which may include, but is not limited to, delays in the installation process and interconnection to the power grid of solar energy systems and other factors. The non-performance fees are settled by either a reimbursement of a portion of the Class A members' capital or an additional payment to the Class A members. During the year ended December 31, 2019 , we paid $1.3 million related to non-performance fees. During the years ended December 31, 2018 and 2017 , we did not make any reimbursements or payments related to non-performance fees. As of December 31, 2019 and 2018 , we recorded a liability of $566,000 and $1.3 million , respectively, related to non-performance fees.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Stockholders' Equity	Stockholders' Equity Series A and Series C Convertible Preferred Stock The Series A and Series C convertible preferred stock was convertible into our Series A common stock at an initial conversion ratio of 1:1 , subject to appropriate adjustment in the event of any stock dividend, stock split, combination or other similar recapitalization with respect to any of our common stock and to broad-based weighted average anti-dilution protection. The Series A and Series C convertible preferred stock was mandatorily convertible into our Series A common stock upon either (a) the closing of a public offering of shares of our common stock with aggregate gross proceeds, net of underwriting discounts and commissions, of not less than $175.0 million at a per share offering price of at least 1.25 times the original purchase price of our Series A convertible preferred stock or (b) the affirmative vote of at least 80% of the shares of Series A and Series C convertible preferred stock voting as a single class and on an "as converted basis". The holders of Series A and Series C convertible preferred stock were entitled to cast the number of votes equal to the number of whole shares of Series A common stock into which the Series A and Series C convertible preferred stock held by such holders is convertible as of the record date for determining stockholders entitled to vote on such matter. In April 2017 , we increased the number of authorized voting shares of our Series A convertible preferred stock from 90,000,000 shares (or 38,576,939 shares as adjusted for the Reverse Stock Split) to 105,000,000 shares (or 45,006,429 shares as adjusted for the Reverse Stock Split). During the year ended December 31, 2017 , we issued 9,409,174 shares (or 4,033,061 shares as adjusted for the Reverse Stock Split) of our Series A convertible preferred stock at $5.3246735 per share in exchange for $50.1 million in cash. Additionally, in October 2017, we retired approximately $15.2 million principal and related paid-in-kind amounts of convertible notes in exchange for 2,852,790 shares (or 1,222,799 shares as adjusted for the Reverse Stock Split) of our Series A convertible preferred stock (see Note 8, Long-Term Debt ). In March 2018 , we further increased the number of authorized voting shares of our convertible preferred stock to 150,000,000 shares (or 64,294,899 shares as adjusted for the Reverse Stock Split), of which 110,000,000 shares (or 47,149,592 shares as adjusted for the Reverse Stock Split) were designated as Series A convertible preferred stock and 40,000,000 shares (or 17,145,306 shares as adjusted for the Reverse Stock Split) were designated as Series C convertible preferred stock. During the year ended December 31, 2018 , we issued 30,344,827 shares (or 13,006,780 shares as adjusted for the Reverse Stock Split) of Series C convertible preferred stock at $5.80 per share in exchange for $176.0 million in cash. See below for non-cash issuance of our Series A convertible preferred stock. In connection with our IPO, we converted 108,138,971 shares (or 46,351,877 shares as adjusted for the Reverse Stock Split) of our Series A convertible preferred stock and 32,958,645 shares (or 14,127,140 shares as adjusted for the Reverse Stock Split) of our Series C convertible preferred stock, which represented all the outstanding shares of our Series A convertible preferred stock and Series C convertible preferred stock, into 60,479,017 shares of our common stock. Series B Convertible Preferred Stock The Series B convertible preferred stock was convertible into our Series A common stock at a rate determined by dividing the original issue price by the conversion price of $3.73 at or after the earlier of (a) November 9, 2018 or (b) immediately prior to the consummation of a sale of Sunnova, subject to appropriate adjustment in the event of any stock dividend, stock split, combination or other similar recapitalization with respect to any of our common stock and to broad-based weighted average anti-dilution protection. The Series B convertible preferred stock was mandatorily convertible into our Series A common stock upon either (a) the closing of the sale of shares of any of our common stock to the public at a price of at least approximately $6.6558 per share (subject to appropriate adjustments) or (b) the affirmative vote of at least 75% of the shares of Series A and Series B convertible preferred stock. Each holder of Series B convertible preferred stock was entitled to cast the number of votes equal to the number of whole shares of Series A common stock into which the Series B convertible preferred stock held by such holder were convertible as of the record date for determining stockholders entitled to vote on such matter. In November 2017 , we authorized 11,000,000 voting shares (or 4,714,959 shares as adjusted for the Reverse Stock Split) of Series B convertible preferred stock. During the year ended December 31, 2017 , we issued 10,693,501 shares (or 4,583,576 shares as adjusted for the Reverse Stock Split) at $3.73 per share in exchange for $39.9 million in cash. In January 2018, we issued 30,360 shares (or 13,013 shares as adjusted for the Reverse Stock Split) of Series B convertible preferred stock at $3.73 per share in exchange for $113,000 in cash. In March 2018 , we exchanged all outstanding shares of Series B convertible preferred stock, plus accrued paid-in-kind interest thereon, for 11,112,285 shares (or 4,763,086 shares as adjusted for the Reverse Stock Split) of Series A convertible preferred stock. Immediately following the exchange, we canceled all shares of Series B convertible preferred stock. As of December 31, 2018 , there was no Series B convertible preferred stock outstanding. Series A Common Stock In November 2017, we increased the number of authorized voting shares of Series A common stock from 150,000,000 shares (or 64,294,899 shares as adjusted for the Reverse Stock Split) to 160,000,000 shares (or 68,581,225 shares as adjusted for the Reverse Stock Split). In March 2018 , we increased the number of authorized voting shares of Series A common stock to 180,000,000 shares (or 77,153,879 shares as adjusted for the Reverse Stock Split), of which 150,000,000 shares (or 64,294,899 shares as adjusted for the Reverse Stock Split) have been reserved for the issuance of Series A common stock upon the conversion of Series A or Series C convertible preferred stock. In connection with our IPO, our Series A common stock was redesignated as common stock. Series B Common Stock Our Series B non-voting common stock related to our equity-based compensation plans (see Note 15, Equity-Based Compensation ). As of December 31, 2018 , the number of shares of common stock authorized was 20,000,000 shares (or 9,544,300 shares as adjusted for the Reverse Stock Split). In connection with our IPO, we converted 23,870 shares of our non-voting Series B common stock, which represented all the outstanding shares of our Series B common stock, into 23,870 shares of our voting Series A common stock, which was subsequently redesignated as common stock. Common Stock On July 24, 2019 , we priced 14,000,000 shares of common stock in our IPO at a public offering price of $12.00 per share and on July 25, 2019 our common stock began trading on the New York Stock Exchange under the symbol "NOVA". On August 19, 2019 , we issued and sold an additional 865,267 shares of our common stock at a public offering price of $12.00 per share pursuant to the underwriters' exercise of their option to purchase additional shares. We received aggregate net proceeds from our IPO of approximately $162.3 million , after deducting underwriting discounts and commissions of approximately $10.7 million and offering expenses of approximately $5.4 million . We recorded the offering costs in other assets in our consolidated balance sheets until closing, at which time the costs were reclassified to additional paid-in capital—common stock. We used a portion of the net proceeds from our IPO to redeem our senior secured notes. See Note 8, Long-Term Debt . We plan to use the remaining net proceeds from our IPO for general corporate purposes, including working capital, operating expenses, capital expenditures and repayment of indebtedness.

Equity-Based Compensation

Equity-Based Compensation	12 Months Ended
	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Equity-Based Compensation	Equity-Based Compensation Effective December 2013 and January 2015, we established and adopted two stock option plans (collectively, the "Prior Plans") after approval by our Board. The Prior Plans provided the aggregate number of shares of common stock that may be issued pursuant to stock options shall not exceed 26,032 shares. No further awards may be made under the Prior Plans. Effective March 2016, we established and adopted a new stock option plan (the "2016 Plan") after approval by our Board. The 2016 Plan allowed for the issuance of non-qualified and incentive stock options. The 2016 Plan provided the aggregate number of shares of common stock that may be issued pursuant to stock options shall not exceed 4,288,950 shares. No further awards may be made under the 2016 Plan. In connection with our IPO, approximately 50% of the non-vested stock options outstanding at that time, or 995,517 stock options, became exercisable and the vesting terms for all remaining stock options were amended so all stock options will be fully vested on the first anniversary of the closing date of our IPO. We recorded an additional $3.2 million of expense in July 2019 related to the accelerated vesting periods. In addition, the stock options awarded under the Prior Plans and the 2016 Plan were adjusted for the Reorganization. The adjusted awards are subject to the same vesting conditions applicable to the awards immediately prior to the Reorganization. In connection with our IPO, our Board adopted the 2019 Long-Term Incentive Plan (the "LTIP") to incentivize employees, officers, directors and other service providers of SEI and its affiliates. The LTIP provides for the grant, from time to time, at the discretion of our Board or a committee thereof, of stock options, stock appreciation rights, stock awards, including restricted stock and restricted stock units, performance awards and cash awards. The LTIP provides the aggregate number of shares of common stock that may be issued pursuant to awards shall not exceed 5,229,318 shares. The number of shares available for issuance under the LTIP will be increased on the first day of each fiscal year beginning in 2020, in an amount equal to the lesser of (a) a number of shares such that the total number of shares that remain available for additional grants under the LTIP equals five percent of the outstanding shares of our common stock on the last day of the immediately preceding fiscal year or (b) such number of shares determined by our Board. Awards granted under the LTIP contain a service condition and cease vesting for employees, consultants and directors upon termination of employment or service. During the year ended December 31, 2019 , we granted 1,431,555 restricted stock units to certain employees and a director with a grant date fair value of $17.1 million , which will be recognized ratably over the applicable vesting period of each award (either one year , three years or seven years ). The Prior Plans and the 2016 Plan will only allow for settlement of stock options by the issuance of common stock and restricted stock units issued under the LTIP can generally only be settled by the issuance of common stock. Therefore, we classify the stock options and restricted stock units as equity awards. We recognize the fair value of equity-based compensation awards as compensation cost in the financial statements, beginning on the grant date. We base compensation cost on the fair value of the awards we expect to vest, recognized over the service period, and adjusted for actual forfeitures that occur before vesting. During the years ended December 31, 2019 , 2018 and 2017 , we recognized $9.2 million , $3.0 million and $1.5 million , respectively, of compensation expense relating to equity-based compensation awards. Stock Options During 2017 , we, with approval of our Board, granted 950,047 stock options (or 407,204 stock options as adjusted for the Reverse Stock Split) to employees. In April 2017, we, with approval of our Board, granted 20,000 stock options (or 8,572 stock options as adjusted for the Reverse Stock Split) to a non-employee consultant. During 2017 , 27,000 stock options (or 11,571 stock options as adjusted for the Reverse Stock Split) were exercised resulting in the issuance of 27,000 shares (or 11,571 shares as adjusted for the Reverse Stock Split) of common stock in exchange for an insignificant amount of cash and 4,750 stock options (or 2,034 stock options as adjusted for the Reverse Stock Split) were net exercised (and thus, no cash was received) resulting in the issuance of 2,663 shares (or 1,141 shares as adjusted for the Reverse Stock Split) of common stock. In May 2017, we modified a stock option agreement with a former employee to require a future expense of $653,000 to be recognized at the earlier of (a) a company liquidity event, as defined, or (b) April 2026, which was recognized in July 2019 in connection with our IPO. During 2018 , we, with approval of our Board, granted 4,222,850 stock options (or 1,810,016 stock options as adjusted for the Reverse Stock Split) to employees. In April 2018, we, with approval of our Board, granted 58,000 stock options (or 24,860 stock options as adjusted for the Reverse Stock Split) to non-employee consultants. During 2018 , 3,250 stock options (or 1,393 stock options as adjusted for the Reverse Stock Split) were net exercised (and thus, no cash was received) resulting in the issuance of 1,505 shares (or 644 shares as adjusted for the Reverse Stock Split) of common stock. During 2019 , we, with approval of our Board, granted 94,295 stock options to employees. During 2019 , 2,143 stock options were exercised resulting in the issuance of 2,143 shares of common stock in exchange for an insignificant amount of cash. We used the following assumptions to apply the Black-Scholes option-pricing model to stock options granted during the years ended December 31, 2019 , 2018 and 2017 : Year Ended 2019 2018 2017 Expected dividend yield 0.00% 0.00% 0.00% Risk-free interest rate 2.62% 2.62% 2.11% Expected term (in years) 7.94 7.94 8.01 Volatility 81% 81% 68% The expected volatility was calculated based on the average historical volatilities of publicly traded peer companies determined by us. The risk-free interest rate used was based on the U.S. treasury yield curve in effect at the time of grant for the expected term of the stock options to be valued. The expected dividend yield is zero as we do not anticipate paying common stock dividends within the relevant time frame. The expected term has been estimated using the average of the contractual term and weighted average life of the stock options. The following table summarizes stock option activity: Number Weighted Weighted Weighted Aggregate (in thousands) Outstanding, December 31, 2017 3,166,008 $ 15.65 8.36 $ 124 Granted 1,834,876 $ 16.26 9.28 $ 3.52 Exercised (1,393 ) $ 1.85 $ 6 Forfeited (191,101 ) $ 15.23 $ 3.33 Outstanding, December 31, 2018 4,808,390 $ 15.90 8.09 $ 129 Granted 94,295 $ 13.58 9.07 $ 3.11 Exercised (2,143 ) $ 1.85 $ 20 Forfeited (596,233 ) $ 15.85 $ 3.48 Outstanding, December 31, 2019 4,304,309 $ 15.86 7.08 $ 242 Exercisable, December 31, 2019 3,339,913 $ 15.86 6.89 $ 242 Vested and expected to vest, December 31, 2019 4,304,309 $ 15.86 7.08 $ 242 Non-vested, December 31, 2018 3,124,367 $ 3.48 Non-vested, December 31, 2019 964,396 $ 3.52 The number of stock options that vested during the years ended December 31, 2019 and 2018 was 1,765,410 and 577,594 , respectively. The grant date fair value of stock options that vested during the years ended December 31, 2019 and 2018 was $6.0 million and $1.8 million , respectively. As of December 31, 2019 , there was $1.5 million of total unrecognized compensation expense related to stock options, which is expected to be recognized over the weighted average period of 0.28 years . Restricted Stock Units The following table summarizes restricted stock unit activity: Number of Weighted Outstanding, December 31, 2018 — Granted 1,431,555 $ 11.93 Forfeited (5,416 ) $ 12.00 Outstanding, December 31, 2019 1,426,139 $ 11.93 No restricted stock units vested during the year ended December 31, 2019 . As of December 31, 2019 , there was $14.3 million of total unrecognized compensation expense related to restricted stock units, which is expected to be recognized over the weighted average period of 2.50 years .

Basic and Diluted Net Loss Per

Basic and Diluted Net Loss Per Share	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Basic and Diluted Net Loss Per Share	Basic and Diluted Net Loss Per Share The following table sets forth the computation of our basic and diluted net loss per share: Year Ended 2019 2018 2017 (in thousands, except share and per share amounts) Net loss attributable to stockholders $ (144,351 ) $ (74,246 ) $ (91,085 ) Dividends earned on Series A convertible preferred stock (19,271 ) (36,346 ) (29,623 ) Dividends earned on Series B convertible preferred stock — — (580 ) Dividends earned on Series C convertible preferred stock (5,454 ) (5,948 ) — Deemed dividends on convertible preferred stock exchange — (19,332 ) — Net loss attributable to common stockholders—basic and diluted $ (169,076 ) $ (135,872 ) $ (121,288 ) Net loss per share attributable to common stockholders—basic and diluted $ (4.14 ) $ (15.74 ) $ (14.05 ) Weighted average common shares outstanding—basic and diluted 40,797,976 8,634,477 8,632,936 The following table presents the weighted average shares of common stock equivalents that were excluded from the computation of diluted net loss per share for the periods presented because including them would have been anti-dilutive: Year Ended 2019 2018 2017 Equity-based compensation awards 4,954,286 4,307,614 3,408,202 Convertible preferred stock 33,960,624 53,112,246 37,977,786 Convertible senior notes 104,320 — —

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Legal. We are a party to a number of lawsuits, claims and governmental proceedings which are ordinary, routine matters incidental to our business. In addition, in the ordinary course of business, we periodically have disputes with dealers and customers. We do not expect the outcomes of these matters to have, either individually or in the aggregate, a material adverse effect on our financial position or results of operations. Performance Guarantee Obligations. As of December 31, 2019 , we recorded $6.5 million relating to our guarantee of certain specified minimum solar energy production output under our leases and loans, of which we include $4.1 million in other current liabilities and $2.4 million in other long-term liabilities in the consolidated balance sheet. As of December 31, 2018 , we recorded $6.0 million relating to these guarantees, of which $2.6 million is included in other current liabilities and $3.5 million is included in other long-term liabilities in the consolidated balance sheet. The changes in our aggregate performance guarantee obligations are as follows: As of December 31, 2019 2018 (in thousands) Balance at beginning of period $ 6,044 $ 4,173 Accruals for obligations issued 3,101 3,033 Settlements made in cash (2,677 ) (1,162 ) Balance at end of period $ 6,468 $ 6,044 Operating and Finance Leases . We lease real estate and certain office equipment under operating leases and certain other office equipment under finance leases. The following table presents the detail of lease expense and lease income as recorded in general and administrative expense and other operating expense (income), respectively, in the consolidated statements of operations: Year Ended 2019 2018 2017 (in thousands) Operating lease expense $ 1,248 $ 972 $ 972 Finance lease amortization expense 8 — — Short-term lease expense 48 50 21 Variable lease expense 1,037 704 661 Sublease income (73 ) (70 ) (41 ) Total $ 2,268 $ 1,656 $ 1,613 The following table presents the detail of right-of-use assets and lease liabilities as recorded in other assets and other current liabilities/other long-term liabilities, respectively, in the consolidated balance sheets: As of December 31, 2019 2018 (in thousands) Right-of-use assets: Operating leases $ 9,668 $ 2,586 Finance leases 5 — Total right-of-use assets $ 9,673 $ 2,586 Current lease liabilities: Operating leases $ 556 $ 871 Finance leases 5 — Long-term leases liabilities Operating leases 9,389 2,083 Total lease liabilities $ 9,950 $ 2,954 Other information related to leases was as follows: Year Ended 2019 2018 2017 (in thousands) Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 1,254 $ 875 $ 814 Financing cash flows from finance leases 8 — — Right-of-use assets obtained in exchange for lease obligations: Operating leases 8,087 — 4,175 Finance leases 13 — — As of December 31, 2019 2018 Weighted average remaining lease term (years): Operating leases 9.41 3.42 Finance leases 0.68 — Weighted average discount rate: Operating leases 3.94 % 4.63 % Finance leases 4.26 % — % Future minimum lease payments under our non-cancelable leases as of December 31, 2019 were as follows: Operating Finance (in thousands) 2020 $ 1,037 $ 5 2021 1,536 — 2022 1,559 — 2023 1,594 — 2024 1,616 — 2025 and thereafter 7,617 — Total 14,959 5 Amount representing interest (2,603 ) — Amount representing leasehold incentives (2,411 ) — Present value of future payments 9,945 5 Current portion of lease liability (556 ) (5 ) Long-term portion of lease liability $ 9,389 $ — Future minimum lease payments under our non-cancelable leases as of December 31, 2018 were as follows: Operating (in thousands) 2019 $ 989 2020 842 2021 863 2022 512 2023 — 2024 and thereafter — Total 3,206 Amount representing interest (252 ) Present value of future payments 2,954 Current portion of lease liability (871 ) Long-term portion of lease liability $ 2,083 Letters of Credit . In connection with various security arrangements for an office lease and merchant banking activities, we have letters of credit outstanding of $725,000 as of December 31, 2019 and 2018 . The letters of credit are cash collateralized for the same amount or a lesser amount and this cash is classified as restricted cash. Guarantees or Indemnifications . We enter into contracts that include indemnifications and guarantee provisions. In general, we enter into contracts with indemnities for matters such as breaches of representations and warranties and covenants contained in the contract and/or against certain specified liabilities. Examples of these contracts include dealer agreements, debt agreements, asset purchases and sales agreements, service agreements and procurement agreements. We are unable to estimate our maximum potential exposure under these agreements until an event triggering payment occurs. We do not expect to make any material payments under these agreements. Dealer Commitments. As of December 31, 2019 , the net unamortized balance of payments to dealers for exclusivity and other similar arrangements was $32.8 million . Under these agreements, we paid $31.7 million during the year ended December 31, 2019 and could be obligated to make maximum payments, excluding additional amounts payable on a per watt basis if even higher thresholds are met, as follows: Dealer (in thousands) 2020 $ 24,184 2021 24,200 2022 25,240 2023 1,000 2024 — 2025 and thereafter — Total $ 74,624 Purchase Commitments. In August 2019, we amended an agreement with a supplier in which we agreed to purchase a minimum amount of energy storage systems for five years. These purchases are recorded to inventory within other current assets in the consolidated balance sheets. Under this agreement, we could be obligated to make minimum purchases as follows: Purchase (in thousands) 2020 $ 22,702 2021 27,359 2022 27,243 2023 27,053 2024 20,152 2025 and thereafter — Total $ 124,509 Information Technology Commitments. We have certain long-term contractual commitments related to information technology software services and licenses. Future commitments as of December 31, 2019 were as follows: Information (in thousands) 2020 $ 4,962 2021 3,269 2022 10 2023 — 2024 — 2025 and thereafter — Total $ 8,241 Restricted Net Assets . Our various financing agreements contain provisions that restrict the ability of certain of our consolidated subsidiaries to transfer their net assets to SEI. Such restricted net assets amounted to approximately $548.1 million as of December 31, 2019 .

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2019
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events SOLI Debt . In February 2020 , we pooled and transferred eligible solar energy systems and the related asset receivables into Sunnova Sol Issuer, LLC ("SOLI"), a special purpose entity, that issued $337.1 million in aggregate principal amount of Series 2020-1 Class A solar asset-backed notes and $75.4 million in aggregate principal amount of Series 2020-1 Class B solar asset-backed notes (collectively, the "SOLI Notes") with a maturity date of January 2055 . The SOLI Notes were issued at a discount of 0.89% for Class A and 0.85% for Class B and bear interest at an annual rate equal to 3.35% and 5.54% , respectively. The cash flows generated by these solar energy systems are used to service the quarterly principal and interest payments on the SOLI Notes and satisfy SOLI's expenses, and any remaining cash can be distributed to Sunnova Sol Depositor, LLC, SOLI's sole member. In connection with the SOLI Notes, certain of our affiliates receive a fee for managing and servicing the solar energy systems pursuant to a transaction management agreement and managing and servicing agreements. In addition, Sunnova Energy Corporation has guaranteed (a) the obligations of certain of our subsidiaries to manage and service the solar energy systems pursuant to management, servicing and transaction management agreements, (b) the managing members' obligations, in such capacity, under the related financing fund's limited liability company agreement and (c) certain of our subsidiaries' obligations to repurchase or substitute certain ineligible solar energy systems eventually sold to SOLI pursuant to the sale and contribution agreement. SOLI is also required to maintain a liquidity reserve account, a tax loss insurance proceeds account and a supplemental reserve account for the benefit of the lenders under the SOLI Notes, each of which must remain funded at all times to the levels specified in the SOLI Notes. The creditors of SOLI have no recourse to our other assets except as expressly set forth in the SOLI Notes. AP4 Debt, TEPIIH Debt and LAPH Debt . In February 2020 , the aggregate outstanding principal amounts under the AP4 financing agreement and TEPIIH revolving credit facility of $92.0 million and $226.6 million , respectively, were fully repaid using proceeds from the SOLI Notes, all related interest rate swaps were unwound and the debt facilities were terminated. In addition, proceeds from the SOLI Notes were used to repay $32.0 million of LAPH debt.

Selected Quarterly Financial Da

Selected Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Information (Unaudited)	Selected Quarterly Financial Data (Unaudited) The following tables present the selected quarterly financial data for the years ended December 31, 2019 and 2018 . Three Months Ended December 31, 2019 September 30, 2019 June 30, 2019 March 31, 2019 (in thousands, except per share amounts) Revenue (1) $ 33,614 $ 36,615 $ 34,612 $ 26,715 Total operating expenses, net (1) $ 42,769 $ 42,513 $ 37,322 $ 31,222 Operating loss (1) $ (9,155 ) $ (5,898 ) $ (2,710 ) $ (4,507 ) Net loss (1)(2) $ (13,762 ) $ (34,369 ) $ (49,807 ) $ (35,496 ) Net loss attributable to common stockholders—basic and diluted (1)(2) $ (17,509 ) $ (37,590 ) $ (63,260 ) $ (50,717 ) Net loss per share attributable to common stockholders—basic and diluted (1)(2) $ (0.21 ) $ (0.62 ) $ (7.32 ) $ (5.87 ) Three Months Ended December 31, 2018 September 30, 2018 June 30, 2018 March 31, 2018 (in thousands, except per share amounts) Revenue (1) $ 25,206 $ 30,429 $ 28,963 $ 19,784 Total operating expenses, net (1)(3) $ 37,623 $ 27,025 $ 26,528 $ 26,936 Operating income (loss) (1)(3) $ (12,417 ) $ 3,404 $ 2,435 $ (7,152 ) Net loss (1)(2) $ (39,102 ) $ (6,647 ) $ (9,224 ) $ (13,436 ) Net loss attributable to common stockholders—basic and diluted (1)(2) $ (53,017 ) $ (17,865 ) $ (23,269 ) $ (41,721 ) Net loss per share attributable to common stockholders—basic and diluted (1)(2) $ (6.14 ) $ (2.07 ) $ (2.69 ) $ (4.83 ) (1) Fluctuations are primarily due to seasonality. (2) Fluctuations are primarily due to unrealized gains and losses on derivative instruments. (3) Fluctuations are primarily due to timing of estimates of losses from natural disasters and recoveries of business interruption insurance proceeds related to 2018.

Schedule I Parent Company Finan

Schedule I Parent Company Financial Statements	12 Months Ended
	Dec. 31, 2019
Condensed Financial Information Disclosure [Abstract]
Schedule I Parent Company Financial Statements	SUNNOVA ENERGY INTERNATIONAL INC. CONDENSED BALANCE SHEETS (in thousands, except share amounts and share par values) As of December 31, 2019 2018 Assets Current assets: Cash $ 696 $ — Total current assets 696 — Investments in subsidiaries 891,330 — Total assets $ 892,026 $ — Liabilities and Stockholders' Equity Current liabilities: Accrued expenses $ 83 $ — Total current liabilities 83 — Long-term debt, net 37,607 — Total liabilities 37,690 — Stockholders' equity: Common stock, 83,980,885 and 0 shares issued as of December 31, 2019 and 2018, respectively, at $0.0001 par value 8 — Additional paid-in capital—common stock 987,760 — Accumulated deficit (133,432 ) — Total stockholders' equity 854,336 — Total liabilities and stockholders' equity $ 892,026 $ — See accompanying notes to parent company condensed financial statements. SUNNOVA ENERGY INTERNATIONAL INC. CONDENSED STATEMENTS OF OPERATIONS (in thousands) Year Ended 2019 2018 2017 Revenue $ — $ — $ — General and administrative expense 418 — — Operating loss (418 ) — — Interest expense 83 — — Equity in losses of subsidiaries 132,933 — — Loss before income tax (133,434 ) — — Income tax — — — Net loss $ (133,434 ) $ — $ — See accompanying notes to parent company condensed financial statements. Year Ended 2019 2018 2017 CASH FLOWS FROM OPERATING ACTIVITIES Net cash used in operating activities $ — $ — $ — CASH FLOWS FROM INVESTING ACTIVITIES Investments in subsidiaries (219,206 ) — — Distributions from subsidiaries 2 — — Net cash used in investing activities (219,204 ) — — CASH FLOWS FROM FINANCING ACTIVITIES Proceeds from long-term debt 38,087 — — Payments of deferred financing costs (377 ) — — Proceeds from issuance of common stock, net 168,204 — — Proceeds from equity component of debt instrument, net 13,984 — — Other, net 2 — — Net cash provided by financing activities 219,900 — — Net increase (decrease) in cash and restricted cash 696 — — Cash at beginning of period — — — Cash at end of period $ 696 $ — $ — Supplemental cash flow information: Cash paid for interest $ — $ — $ — Cash paid for income taxes $ — $ — $ — See accompanying notes to parent company condensed financial statements. Basis of Presentation On July 24, 2019 Sunnova Energy International Inc. ("SEI") priced 14,000,000 shares of its common stock at a public offering price of $12.00 per share and on July 25, 2019 SEI's common stock began trading on the New York Stock Exchange under the symbol "NOVA". Upon the closing of our initial public offering on July 29, 2019 (our "IPO"), Sunnova Energy Corporation was contributed to SEI and SEI became the holding company of Sunnova Energy Corporation through a reverse merger. In addition, the historical financial statements of Sunnova Energy Corporation became the historical financial statements of SEI. These condensed financial statements include the condensed balance sheets, condensed statements of operations and condensed statements of cash flows and have been prepared on a parent-only basis. These parent-only financial statements do not include all of the information and notes required by accounting principles generally accepted in the United States of America for annual financial statements and therefore, these parent-only financial statements and other information included should be read in conjunction with SEI's consolidated financial statements and related notes contained within this Annual Report on Form 10-K . Guarantees As of December 31, 2019 and 2018 , our parent company has not issued any guarantees on behalf of its wholly-owned subsidiaries.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying annual audited consolidated financial statements (" consolidated financial statements ") include our consolidated balance sheets, statements of operations, statements of redeemable noncontrolling interests and stockholders' equity and statements of cash flows and have been prepared in accordance with accounting principles generally accepted in the United States of America ("GAAP") from records maintained by us. Our consolidated financial statements reflect our accounts and operations and those of our subsidiaries in which we have a controlling financial interest. In accordance with the provisions of the Financial Accounting Standards Board ("FASB") Accounting Standards Codification ("ASC") 810, Consolidation , we consolidate any VIE of which we are the primary beneficiary. We form VIEs with our investors in the ordinary course of business to facilitate the funding and monetization of certain attributes associated with our solar energy systems. The typical condition for a controlling financial interest ownership is holding a majority of the voting interests of an entity; however, a controlling financial interest may also exist in entities, such as VIEs, through arrangements that do not involve controlling voting interests. ASC 810 requires a variable interest holder to consolidate a VIE if that party has (a) the power to direct the activities of the VIE that most significantly impact the VIE's economic performance and (b) the obligation to absorb losses or the right to receive benefits from the VIE that could potentially be significant to the VIE. We do not consolidate a VIE in which we have a majority ownership interest when we are not considered the primary beneficiary. We have considered the provisions within the contractual arrangements that grant us power to manage and make decisions that affect the operation of our VIEs, including determining the solar energy systems contributed to the VIEs, and the installation, operation and maintenance of the solar energy systems. We consider the rights granted to the other investors under the contractual arrangements to be more protective in nature rather than participating rights. As such, we have determined we are the primary beneficiary of our VIEs and evaluate our relationships with our VIEs on an ongoing basis to ensure we continue to be the primary beneficiary. We have eliminated all intercompany accounts and transactions in consolidation.
Reclassifications	Reclassifications Certain prior period amounts have been reclassified to conform to the current period presentation. These reclassifications did not have a significant impact on our consolidated financial statements .
Use of Estimates	Use of Estimates The application of GAAP in the preparation of the consolidated financial statements requires us to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. We base our estimates on historical experience and on various other assumptions believed to be reasonable, the results of which form the basis for making judgments about the carrying values of assets and liabilities. Actual results could differ materially from those estimates.
Cash and Restricted Cash	Cash We maintain cash, which consists principally of demand deposits, with investment-grade financial institutions. We are exposed to credit risk to the extent cash balances exceed amounts covered by the Federal Deposit Insurance Corporation ("FDIC"). As of December 31, 2019 and 2018 , we had cash deposits of $72.4 million and $46.3 million , respectively, in excess of the FDIC's current insured limit of $250,000. We have not experienced any losses on our deposits of cash. Restricted Cash We record cash that is restricted as to withdrawal or use under the terms of certain contractual agreements as restricted cash. Our restricted cash primarily represents cash held to service certain payments under the Sunnova AP 6 Warehouse II, LLC ("AP6WII"), Helios Issuer, LLC ("HELI"), Sunnova LAP Holdings, LLC ("LAPH"), Sunnova EZ-Own Portfolio, LLC ("EZOP"), Sunnova TEP I, LLC ("TEPI"), Sunnova TEP I Holdings, LLC ("TEPIH"), Sunnova TEP II, LLC ("TEPII"), Sunnova TEP II-B, LLC ("TEPIIB"), Sunnova TEP III, LLC ("TEPIII"), Sunnova TEP IV-A, LLC ("TEPIVA"), Sunnova TEP IV-B, LLC ("TEPIVB"), Sunnova TEP Holdings, LLC ("TEPH"), Sunnova TEP II Holdings, LLC ("TEPIIH"), Helios II Issuer, LLC ("HELII"), Helios III Issuer, LLC ("HELIII"), Sunnova RAYS I Issuer, LLC ("RAYSI") and Sunnova TEP Inventory, LLC ("TEPINV") financing arrangements (see Note 8, Long-Term Debt and Note 13, Redeemable Noncontrolling Interests ) and balances collateralizing outstanding letters of credit related to one of our operating leases for office space (see Note 17, Commitments and Contingencies We are exposed to credit risk to the extent restricted cash balances exceed amounts covered by the FDIC. As of December 31, 2019 and 2018 , we had restricted cash deposits of $63.6 million and $31.8 million , respectively, in excess of the FDIC's current insured limit of $250,000. We have not experienced any losses on our deposits of restricted cash.
Accounts Receivable	Accounts Receivable Accounts Receivable — Trade. Accounts receivable — Accounts Receivable — Other. Accounts receivable — other primarily represents amounts owed from dealers in a net receivable position primarily as a result of customer contract cancelations or settlement agreements and receivables related to the sale of inventory.
Inventory	Inventory
Concentration of Risk	Concentrations of Risk Financial instruments that potentially subject us to concentrations of credit risk consist primarily of cash, restricted cash, accounts receivable and notes receivable. The concentrated risk associated with cash and restricted cash is mitigated by our policy of banking with creditworthy institutions. Typically, amounts on deposit with certain banking institutions exceed FDIC insurance limits. We do not generally require collateral or other security to support accounts receivable. To reduce credit risk related to our relationship with our dealers, management performs periodic credit evaluations and ongoing assessments of our dealers' financial condition.
Dealer Commitments	Dealer Commitments Throughout 2019, we entered into exclusivity and other similar agreements with certain key dealers pursuant to which we have agreed to pay an incentive if such dealers install a certain minimum number of solar energy systems within specified periods. These incentives are recorded in other assets in the consolidated balance sheets and are amortized to general and administrative expense in the consolidated statements of operations generally over the term of the customer agreements, which is estimated at an average of 23 years . See Note 17, Commitments and Contingencies .
Fair Value of Financial Instruments	Fair Value of Financial Instruments Fair value is an exit price representing the amount 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. As such, fair value is a market-based measurement that should be determined based on assumptions market participants would use in pricing an asset or a liability. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. ASC 820 establishes a three-tier fair value hierarchy, which prioritizes inputs that may be used to measure fair value as follows: • Level 1—Observable inputs that reflect unadjusted quoted market prices in active markets for identical assets or liabilities that are accessible at the measurement date. • Level 2—Observable inputs other than Level 1 prices, such as quoted market prices for similar assets or liabilities in active markets, quoted market prices 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 assets or liabilities. • 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. In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, the level in the fair value hierarchy must be determined based on the lowest level input that is significant to the fair value measurement. An assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment and consideration of factors specific to the asset or liability. Our financial instruments include accounts receivable, notes receivable, accounts payable, accrued expenses, long-term debt and interest rate swaps and swaptions. The carrying values of accounts receivable, accounts payable and accrued expenses approximate the fair values due to the fact that they are short-term in nature (Level 1). We estimate the fair value of our customer notes receivable based on interest rates currently offered under the loan program with similar maturities and terms (Level 3). We estimate the fair value of our fixed-rate long-term debt, excluding the senior secured notes for which we selected the fair value option and the convertible senior notes, based on interest rates currently offered for debt with similar maturities and terms (Level 3). We estimate the fair value of the senior secured notes and convertible senior notes based on a market approach model using Level 3 inputs that incorporates a binomial tree model and a discounted future cash flow model. We determine the fair values of the interest rate derivative transactions based on a discounted cash flow method using contractual terms of the transactions. The floating interest rate is based on observable rates consistent with the frequency of the interest cash flows (Level 2). See Note 7, Customer Notes Receivable , Note 8, Long-Term Debt and Note 9, Derivative Instruments .
Derivative Instruments	Derivative Instruments Our derivative instruments consist of interest rate swaps and swaptions that are not designated as cash flow hedges or fair value hedges under accounting guidance. We use interest rate swaps and swaptions to manage our net exposure to interest rate changes. We record the derivatives in other current assets, other assets, other current liabilities and other long-term liabilities, as appropriate, in the consolidated balance sheets and the changes in fair value are recorded in interest expense, net in the consolidated statements of operations. We include unrealized gains and losses on derivatives as a non-cash reconciling item in operating activities in the consolidated statements of cash flows. We include realized gains and losses on derivatives as a change in components of operating assets and liabilities in operating activities in the consolidated statements of cash flows. See Note 9, Derivative Instruments .
Revenue / Loans / Deferred Revenue	We recognize revenue from contracts with customers as we satisfy our performance obligations at a transaction price reflecting an amount of consideration based upon an estimated rate of return. We express this rate of return as the solar rate per kilowatt hour ("kWh") in the customer contract. The amount of revenue we recognize does not equal customer cash payments because we satisfy performance obligations ahead of cash receipt or evenly as we provide continuous access on a stand-ready basis to the solar energy system. We reflect the differences between revenue recognition and cash payments received in accounts receivable, other assets or deferred revenue, as appropriate. Revenue allocated to remaining performance obligations represents contracted revenue we have not yet recognized and includes deferred revenue as well as amounts that will be invoiced and recognized as revenue in future periods. Contracted but not yet recognized revenue was approximately $1.1 billion as of December 31, 2019 , of which we expect to recognize approximately 4% over the next 12 months . We do not expect the annual recognition to vary significantly over approximately the next 20 years as the vast majority of existing solar service agreements have at least 20 years remaining , given the average age of the fleet of solar energy systems under contract is less than three years . PPAs. Customers purchase electricity from us under PPAs. Pursuant to ASC 606, we recognize revenue based upon the amount of electricity delivered as determined by remote monitoring equipment at solar rates specified under the PPAs. All customers must pass our credit evaluation process. The PPAs generally have a term of 25 years with an opportunity for customers to renew for up to an additional 10 years , via two five -year renewal options. Leases . We are the lessor under lease agreements for solar energy systems and energy storage systems, which do not meet the definition of a lease under ASC 842 and are accounted for as contracts with customers under ASC 606. We recognize revenue on a straight-line basis over the contract term as we satisfy our obligation to provide continuous access to the solar energy system. All customers must pass our credit evaluation process. The lease agreements generally have a term of 25 years with an opportunity for customers to renew for up to an additional 10 years , via two five -year renewal options. We provide customers under our lease agreements a performance guarantee that each solar energy system will achieve a certain specified minimum solar energy production output, which is a significant proportion of its expected output. The specified minimum solar energy production output may not be achieved due to natural fluctuations in the weather or equipment failures from exposure and wear and tear outside of our control, among other factors. We determine the amount of the guaranteed output based on a number of different factors, including: (a) the specific site information relating to the tilt of the panels, azimuth (a horizontal angle measured clockwise in degrees from a reference direction) of the panels, size of the system, and shading on site; (b) the calculated amount of available irradiance (amount of energy for a given flat surface facing a specific direction) based on historical average weather data and (c) the calculated amount of energy output of the solar energy system. While actual irradiance levels can significantly change year over year due to natural fluctuations in the weather, we expect the levels to average out over the term of a 25-year lease and to approximate the levels used in determining the amount of the performance guarantee. Generally, weather fluctuations are the most likely reason a solar energy system may not achieve a certain specified minimum solar energy production output. If the solar energy system does not produce the guaranteed production amount, we are required to refund a portion of the previously remitted customer payments, where the repayment is calculated as the product of (a) the shortfall production amount and (b) the dollar amount (guaranteed rate) per kWh that is fixed throughout the term of the contract. These remittances of a customer's payments, if needed, are payable in January following the end of the first three years of the solar energy system's placed in service date and then every annual period thereafter. See Note 17, Commitments and Contingencies . Solar Renewable Energy Certificates. Each solar renewable energy certificate ("SREC") represents one megawatt hour ( 1,000 kWh) generated by a solar energy system. SRECs can be sold with or without the actual electricity associated with the renewable-based generation source. We account for the SRECs we generate from our solar energy systems as governmental incentives with no costs incurred to obtain them and do not consider those SRECs output of the underlying solar energy systems. We classify these SRECs as inventory held until sold and delivered to third parties. As we did not incur costs to obtain these governmental incentives, the inventory carrying value for the SRECs was $0 as of December 31, 2019 and 2018 . We enter into economic hedges related to expected production of SRECs through forward contracts. The contracts require us to physically deliver the SRECs upon settlement. We recognize the related revenue under ASC 606 upon satisfaction of the performance obligation to transfer the SRECs to the stated counterparty. Payments are typically received within one month of transferring the SREC to the counterparty. The costs related to the sales of SRECs are limited to broker fees (included in cost of revenue—other), which are only paid in connection with certain transactions. Loans. See discussion of loan revenue in the "Loans" section below. Other Revenue. Other revenue includes certain state incentives, revenue from the direct sale of energy storage systems to customers and sales of service plans. We recognize revenue from state incentives in the periods in which they are incurred. We recognize revenue from the direct sale of energy storage systems in the period in which the storage components are placed in service. Service plans are available to customers whose solar energy system was not originally sold by Sunnova. We recognize revenue from service plan contracts over the life of the contract, which is typically five years . Loans We offer a loan program, under which the customer finances the purchase of a solar energy system or energy storage system through a solar service agreement, typically for a term of 10 or 25 years . We recognize cash payments received from customers on a monthly basis under our loan program (a) as interest income, to the extent attributable to earned interest on the contract that financed the customer's purchase of the solar energy system or energy storage system; (b) as a reduction of a note receivable on the balance sheet, to the extent attributable to a return of principal (whether scheduled or prepaid) on the contract that financed the customer's purchase of the solar energy system or energy storage system; and (c) as revenue, to the extent attributable to payments for operations and maintenance services provided by us. To qualify for the loan program, a customer must pass our credit evaluation process, which requires the customer to have a minimum FICO ® score of 650 to 720 Deferred Revenue Revenue
Performance Guarantee Obligations	Performance Guarantee Obligations We guarantee certain specified minimum solar energy production output under our leases and loan agreements, generally over a term of 25 years . The amounts are generally measured and credited to the customer's account in January following the end of the first three years of the solar energy system's placed in service date and then every annual period thereafter. We monitor the solar energy systems to ensure these outputs are achieved. We evaluate if any amounts are due to our customers based upon not meeting the guaranteed solar energy production outputs at each reporting period end. For leases, these estimated amounts are recorded as a reduction to revenues from customers and a current or long-term liability, as applicable. For loans, these estimated amounts are recorded as an increase to cost of revenue—other and a current or long-term liability, as applicable. See Note 17, Commitments and Contingencies .
Property and Equipment	Property and Equipment Solar Energy Systems. Depreciation and amortization of solar energy systems are calculated using the straight-line method over the estimated useful lives of the solar energy systems and are included in cost of revenue—depreciation. While solar energy systems are in the design, construction and installation stages prior to being placed in service, the development of the systems is accounted for through construction in progress. The components of the design, construction and installation of the solar energy systems, which are installed on or near residential rooftops, are as follows: • Dealer's costs (engineering, procurement and construction) • Direct costs (costs directly related to a solar energy system) • Indirect costs (costs incurred in the design, construction and installation of the solar energy system but not directly associated with a particular asset) Solar energy systems are carried at the cost of acquisition or construction (including design and installation) less certain utility rebates and federal and state tax incentives (including federal investment tax credits, known as "Section 48(a) ITCs") and are depreciated over the useful lives of the assets. We account for the Section 48(a) ITCs in accordance with the deferral gross up method, thus reducing the cost basis of the qualifying solar energy systems by the rate applicable to Section 48(a) ITCs, currently 30% for qualifying solar energy systems that began construction before 2020. However, as discussed in Note 10, Income Taxes , we have a full valuation allowance, which is recorded against deferred income taxes and requires the gross up of the basis of the qualifying solar energy systems back to the full value. Depreciation begins when a solar energy system is placed in service. Costs associated with repair and maintenance of a solar energy system are expensed as incurred. Costs associated with improvements to a solar energy system, which extend the life, increase the capacity or improve the efficiency of the systems, are capitalized and depreciated over the remaining life of the asset. Property and Equipment, Excluding Solar Energy Systems . Property and equipment, including information technology system projects, computers and equipment, leasehold improvements, furniture and fixtures, vehicles and other property and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation and amortization are calculated using the straight-line method over the estimated useful lives of the respective assets and are included in general and administrative expense. Leasehold improvements are amortized over the shorter of the lease term or the estimated useful lives. Upon disposition, the cost and related accumulated depreciation of the assets are removed from property and equipment and the resulting gain or loss is reflected in the consolidated statements of operations. Repair and maintenance costs are expensed as incurred. Capitalization of Interest Costs . We capitalize interest on solar energy systems during the development, design, installation and test phase (construction), generally over a period of four months . We determine which debt instruments represent a reasonable measure of the cost of financing construction in terms of interest costs incurred that otherwise could have been avoided. Interest can only be capitalized for debt instruments related to financing the construction of solar energy systems; interest cannot be capitalized for debt instruments related to the acquisition of solar energy systems already constructed and/or in service. These debt instruments and associated interest costs are included in the calculation of the weighted average interest rate used for determining the capitalization rate. Once a solar energy system is placed in service, capitalized interest, as a component of the total cost of the construction, is depreciated over the estimated useful life of the solar energy system.
Intangibles	Intangibles Our intangible assets primarily consist of a software license and a trademark related to the design process of solar energy systems and are stated at cost less accumulated amortization. We amortize intangible assets to general and administrative expense over a useful life of three years
Deferred Financing Costs	Deferred Financing Costs Deferred financing costs are capitalized and amortized to interest expense, net over the term of the related debt using the effective interest method for term loans or the straight-line method for revolving credit facilities. The unamortized balance of deferred financing costs is included in current portion of long-term debt, current portion of long-term debt—affiliates, long-term debt, net and long-term debt, net—affiliates (see Note 8, Long-Term Debt
AROs	AROs We have AROs arising from contractual requirements to perform certain asset retirement activities at the time the solar energy systems are disposed. We recognize an ARO at the point an obligating event takes place, typically when the solar energy system is placed in service. An asset is considered retired when it is permanently taken out of service, such as through a sale or disposal. The liability is initially measured at fair value (as a Level 3 measurement) based on the present value of estimated removal and restoration costs and subsequently adjusted for changes in the underlying assumptions and for accretion expense. The accretion expense is recognized in general and administrative expense in the consolidated statements of operations. The corresponding asset retirement costs are capitalized as part of the carrying amount of the solar energy system and depreciated (for which the expense is included in cost of revenue — depreciation) over the solar energy system's remaining useful life. See Note 6, AROs .
Warranty Obligations	Warranty Obligations In connection with our solar service agreements, we warrant the solar energy systems against defects in workmanship, against component or materials breakdowns and against any damages to rooftops during the installation process. The dealers' warranties on the workmanship, including work during the installation process, and the manufacturers' warranties over component parts have a range of warranty periods which are generally 10 to 25 years
Advertising Costs	Advertising Costs
Defined Contribution Plan	Defined Contribution Plan
Income Taxes	Income Taxes We account for income taxes under an asset and liability approach. Deferred income taxes reflect the impact of temporary differences between assets and liabilities recognized for financial reporting purposes and the amounts recognized for income tax reporting purposes, net operating loss, carryforwards, and other tax credits measured by applying currently enacted tax laws. A valuation allowance is provided when necessary to reduce deferred tax assets to an amount that is more likely than not to be realized. We determine whether a tax position taken in a filed tax return, planned to be taken in a future tax return or claim, or otherwise subject to interpretation, is more likely than not to be sustained upon examination, including resolution of any related appeals or litigation processes, based on the technical merits of the position, or prospectively approved when such approval may be sought in advance. We use a two-step approach to recognize and measure uncertain tax positions. The first step is to evaluate the tax position for recognition by determining if the available evidence indicates it is more likely than not the position will be sustained upon tax authority examination, including resolution of related appeals or litigation processes, if any. The second step is to measure the tax benefit or obligation as the largest amount that is more than 50% likely of being realized upon ultimate settlement. See Note 10, Income Taxes .
Comprehensive Income (Loss)	Comprehensive Income (Loss) We are required to report comprehensive income (loss), which includes net income (loss) as well as other comprehensive income (loss). There were no differences between comprehensive loss and net loss as reported in the consolidated statements of operations for the periods presented.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets Long-lived assets, such as property and equipment, are reviewed for impairment whenever events or changes in circumstances indicate the carrying amount of an asset may not be recoverable. If circumstances require a long-lived asset be tested for possible impairment, we first compare undiscounted cash flows expected to be generated by that asset or asset group to its carrying value. If the carrying value of the long-lived asset or asset group is not recoverable on an undiscounted cash flow basis, impairment is recognized to the extent the carrying value exceeds its fair value. Fair value is determined through various valuation techniques including discounted cash flow models, quoted market values and third-party independent appraisals as considered necessary. Impairment charges are included in operations and maintenance
Segment Information	Segment Information Operating segments are defined as components of a company about which separate financial information is available that is evaluated regularly by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. Our chief operating decision maker is the chief executive officer. Based on the financial information presented to and reviewed by our chief operating decision maker in deciding how to allocate resources and in assessing performance, we have determined we have a single reportable segment: solar energy products and services. Our principal operations, revenue and decision-making functions are located in the U.S.
Basic and Diluted Net Income (Loss) Per Share	Basic and Diluted Net Income (Loss) Per Share Our basic net income (loss) per share attributable to common stockholders is calculated by dividing the net income (loss) attributable to the common stockholders by the weighted-average number of shares of common stock outstanding for the period. Cumulative dividends owed to convertible preferred stockholders (as defined in Note 14, Stockholders' Equity ) decrease (increase) the income (loss) available to common stockholders. The diluted net income (loss) per share attributable to common stockholders is computed by giving effect to all potential common stock equivalents outstanding for the period determined using the treasury stock method or the if-converted method, as applicable. During periods in which we incur a net loss attributable to common stockholders, stock options are considered to be common stock equivalents but are excluded from the calculation of diluted net loss per share attributable to common stockholders as the effect is antidilutive. See Note 16, Basic and Diluted Net Loss Per Share .
Equity-Based Compensation	Equity-Based Compensation We account for equity-based compensation, which requires the measurement and recognition of compensation expense related to the fair value of equity-based compensation awards. Equity-based compensation expense includes the compensation cost for all share-based awards granted to employees, consultants and members of our board of directors (our "Board") based on the grant date fair value estimate. This also applies to awards modified, repurchased or canceled during the periods reported. We use the Black-Scholes option-pricing model to measure the fair value of stock options at the measurement date. We use the closing price of our common stock on the grant date to measure the fair value of restricted stock units at the measurement date. We account for forfeitures as they occur. Equity-based compensation expense is included in general and administrative expense in the consolidated statements of operations. See Note 15, Equity-Based Compensation .
Redeemable Noncontrolling Interests	Redeemable Noncontrolling Interests Redeemable noncontrolling interests represent third-party interests in the net assets of certain consolidated subsidiaries (the "tax equity entities"), which were created to finance the cost of solar energy systems under long-term solar service agreements. The contractual provisions of the financing arrangements represent substantive profit sharing arrangements. We determined the appropriate methodology for attributing income and loss to the redeemable noncontrolling interests is a balance sheet approach referred to as the hypothetical liquidation at book value ("HLBV") method. We, therefore, determine the amount of the redeemable noncontrolling interests in the net assets of the subsidiaries at each balance sheet date using the HLBV method, which is presented in the consolidated balance sheets as redeemable noncontrolling interests. Under the HLBV method, the amounts reported as redeemable noncontrolling interests in the consolidated balance sheets represent the amounts the third parties would hypothetically receive at each balance sheet date under the liquidation provisions of the financing arrangements, assuming the net assets of the subsidiaries were liquidated at the recorded amounts determined in accordance with GAAP and distributed to the third parties. The third parties' interests in the results of operations of the subsidiaries are determined as the difference in the redeemable noncontrolling interests balances in the consolidated balance sheets between the start and end of each reporting period, after taking into account any capital transactions, such as contributions and distributions, between the subsidiaries and the third parties. However, the redeemable noncontrolling interests balance is at least equal to the redemption amount. The estimated redemption value is calculated using the discounted cash flows attributable to the third parties subsequent to the reporting date. We classify redeemable noncontrolling interests with redemption features that are not solely within our control outside of permanent equity in our consolidated balance sheets.
New Accounting Guidance	New Accounting Guidance New accounting pronouncements are issued by the FASB or other standard setting bodies and are adopted as of the specified effective date. In June 2016, the FASB issued Accounting Standards Update ("ASU") No. 2016-13, Financial Instruments—Credit Losses , which will require entities to use a forward-looking expected loss approach instead of the incurred loss approach in effect today when estimating the allowance for credit losses. This ASU is effective for annual and interim reporting periods in 2020. In 2018 and 2019, the FASB issued the following ASUs related to ASU 2016-13: ASU No. 2018-19, Codification Improvements to Topic 326, Financial Instruments—Credit Losses , ASU 2019-05, Financial Instruments—Credit Losses: Targeted Transition Relief and ASU 2019-11, Codification Improvements to Topic 326, Financial Instruments—Credit Losses . The supplemental ASUs must be adopted simultaneously with ASU 2016-13. We are currently evaluating the impact of this ASU on our consolidated financial statements and related disclosures. In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement: Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement , which modifies the disclosure requirements on fair value measurements. This ASU is effective for annual and interim reporting periods in 2020. We adopted this ASU in January 2020 and determined it did not have a significant impact on our consolidated financial statements and related disclosures. In August 2018, the FASB issued ASU No. 2018-15, Intangibles—Goodwill and Other—Internal-Use Software: Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement that is a Service Contract , which requires certain implementation costs to be capitalized. This ASU is effective for annual and interim reporting periods in 2020. We adopted this ASU in January 2020 and determined it did not have a significant impact on our consolidated financial statements and related disclosures. In April 2019, the FASB issued ASU No. 2019-04, Codification Improvements to Topic 326, Financial Instruments—Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments , to clarify and address implementation issues around the new standards related to credit losses, hedging and recognizing and measuring financial instruments. Amendments in this ASU related to credit losses and hedging have the same effective dates as the respective standards unless an entity has already adopted the standards, in which case the amendments are effective for annual and interim reporting periods in 2020. Amendments in this ASU related to recognizing and measuring financial instruments are effective for annual and interim reporting periods in 2020 (see ASU No. 2016-13 above). We adopted this ASU in January 2020 and determined it did not have a significant impact on our consolidated financial statements and related disclosures. In December 2019, the FASB issued ASU No. 2019-12, Income Taxes: Simplifying the Accounting for Income Taxes , to remove certain exceptions and clarify and amend the existing guidance. This ASU is effective for annual and interim reporting periods in 2021. We have not yet determined the potential impact of this ASU on our consolidated financial statements and related disclosures.

Significant Accounting Polici_3

Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Details of Restricted Cash	The following table presents the detail of restricted cash as recorded in other current assets and other assets in the consolidated balance sheets: As of December 31, 2019 2018 (in thousands) Debt and inverter reserves $ 55,407 $ 28,225 Tax equity reserves 9,904 4,796 Letters of credit for office lease 725 725 Other 770 594 Total (1) $ 66,806 $ 34,340 (1) Of this amount, $10.5 million and $5.2 million is recorded in other current assets as of December 31, 2019 and 2018 , respectively.
Changes in the Allowance for Doubtful Accounts	The following table presents the changes in the allowance for doubtful accounts recorded against accounts receivable — trade, net in the consolidated balance sheets: As of December 31, 2019 2018 (in thousands) Balance at beginning of period $ 723 $ 427 Bad debt expense 1,645 1,119 Write off of uncollectible accounts (1,498 ) (861 ) Recoveries 90 50 Other, net — (12 ) Balance at end of period $ 960 $ 723
Schedule of Inventory	The following table presents the detail of inventory as recorded in other current assets in the consolidated balance sheets: As of December 31, 2019 2018 (in thousands) Energy storage systems and components $ 33,443 $ 8,394 Modules and inverters 10,137 433 Meters 169 360 Total $ 43,749 $ 9,187
Schedule of Fair Value of Financial Liabilities	The following table summarizes the change in fair value of our financial liabilities accounted for at fair value on a recurring basis using Level 3 inputs as recorded in long-term debt, net—affiliates in the consolidated balance sheets: As of December 31, 2019 2018 (in thousands) Balance at beginning of period $ — $ — Additions 55,506 — Change in fair value 730 — Extinguishment (56,236 ) — Balance at end of period $ — $ —
Disaggregation of Revenue	The following table presents the detail of revenue as recorded in the consolidated statements of operations: Year Ended 2019 2018 2017 (in thousands) PPA revenue $ 48,041 $ 38,950 $ 29,171 Lease revenue 40,191 33,079 21,866 Solar renewable energy certificate revenue 38,453 30,630 24,833 Loan revenue 1,645 933 479 Other revenue 3,226 790 507 Total $ 131,556 $ 104,382 $ 76,856
Changes in Allowance for Customer Notes Receivable	The following table presents the changes in the allowance for losses recorded against customer notes receivable in the consolidated balance sheets: As of December 31, 2019 2018 (in thousands) Balance at beginning of period $ 710 $ 602 Bad debt expense 419 238 Write off of uncollectible accounts (38 ) (130 ) Balance at end of period $ 1,091 $ 710
Deferred Revenue Schedule	The following table presents the detail of deferred revenue as recorded in other current liabilities and other long-term liabilities in the consolidated balance sheets: As of December 31, 2019 2018 (in thousands) Loans $ 46,958 $ 27,793 PPAs and leases 8,895 6,255 SRECs 3,000 — Total (1) $ 58,853 $ 34,048 (1) Of this amount, $2.1 million and $1.6 million is recorded in other current liabilities as of December 31, 2019 and 2018 , respectively.
Schedule of Intangible Assets	The following table presents the detail of intangible assets as recorded in other assets in the consolidated balance sheets: As of December 31, 2019 2018 (in thousands) Software license $ 331 $ 331 Trademark 68 68 Other 88 — Intangibles, gross 487 399 Less: accumulated amortization (420 ) (399 ) Intangibles, net $ 67 $ —
Changes in Net Deferred Financing Costs	The following table presents the changes in net deferred financing costs: As of December 31, 2019 2018 (in thousands) Balance at beginning of period $ 22,712 $ 25,188 Capitalized 12,731 6,598 Amortized (9,822 ) (9,074 ) Balance at end of period $ 25,621 $ 22,712

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Property and Equipment	The following table presents the detail of property and equipment, net as recorded in the consolidated balance sheets: As of December 31, Useful Lives 2019 2018 (in years) (in thousands) Solar energy systems 35 $ 1,689,457 $ 1,311,458 Construction in progress 143,449 77,847 AROs 30 26,967 17,381 Information technology systems 3 28,320 17,380 Computers and equipment 3-5 1,499 1,251 Leasehold improvements 3-6 1,014 883 Furniture and fixtures 7 735 735 Vehicles 4 1,632 548 Other 5-6 146 52 Property and equipment, gross 1,893,219 1,427,535 Less: accumulated depreciation (148,159 ) (99,078 ) Property and equipment, net $ 1,745,060 $ 1,328,457

Natural Disaster Losses (Tables

Natural Disaster Losses (Tables)	12 Months Ended
	Dec. 31, 2019
Unusual or Infrequent Items, or Both [Abstract]
Schedule of Disaster Losses	The impact of the natural disaster losses as recorded in the consolidated statements of operations for the years ended December 31, 2019 , 2018 and 2017 is as follows: Year Ended 2019 2018 2017 (in thousands) Operations and maintenance expense: Impairment of solar energy systems due to natural disaster losses $ — $ 5,840 $ 6,745 Insurance proceeds received/expected to be received—property damage 54 (53 ) (5,922 ) Insurance proceeds received—business interruption — (2,693 ) (1,307 ) Other natural disaster-related charges — 1,679 65 General and administrative expense: Other natural disaster-related charges — 750 146 Total $ 54 $ 5,523 $ (273 )

Detail of Certain Balance She_2

Detail of Certain Balance Sheet Captions (Tables)	12 Months Ended
	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Other Current Assets	The following table presents the detail of other current assets as recorded in the consolidated balance sheets: As of December 31, 2019 2018 (in thousands) Prepaid inventory $ 96,167 $ — Inventory 43,749 9,187 Current portion of customer notes receivable 13,758 7,601 Other prepaid assets 7,380 2,739 Current portion of other notes receivable 982 1,522 Deferred receivables 1,506 555 Restricted cash 10,474 5,190 Total $ 174,016 $ 26,794
Schedule of Other Current Liabilities	The following table presents the detail of other current liabilities as recorded in the consolidated balance sheets: As of December 31, 2019 2018 (in thousands) Interest payable $ 14,680 $ 8,150 Current portion of performance guarantee obligations 4,067 2,580 Current portion of lease liability 561 871 Deferred revenue 2,086 1,593 Other 410 20 Total $ 21,804 $ 13,214

AROs (Tables)

AROs (Tables)	12 Months Ended
	Dec. 31, 2019
Asset Retirement Obligation Disclosure [Abstract]
Schedule of Changes in AROs	The following table presents the changes in AROs as recorded in other long-term liabilities in the consolidated balance sheets: As of December 31, 2019 2018 (in thousands) Balance at beginning of period $ 20,033 $ 15,347 Additional obligations incurred 4,641 3,607 Accretion expense 1,443 1,183 Change in estimate 4,983 — Other (47 ) (104 ) Balance at end of period $ 31,053 $ 20,033

Customer Notes Receivable (Tabl

Customer Notes Receivable (Tables)	12 Months Ended
	Dec. 31, 2019
Receivables [Abstract]
Fair Values of Notes Receivable and Corresponding Carrying Amounts	The fair values of our customer notes receivable and the corresponding carrying amounts are as follows: As of December 31, 2019 As of December 31, 2018 Carrying Estimated Carrying Estimated (in thousands) Customer notes receivable $ 311,732 $ 314,222 $ 179,632 $ 179,990

Long-Term Debt (Tables)

Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	The following table presents the detail of long-term debt, net and long-term debt, net—affiliates as recorded in the consolidated balance sheets: Year Ended As of December 31, 2019 Year Ended As of December 31, 2018 Long-term Current Long-term Current (in thousands, except interest rates) SEI Convertible senior notes 7.75 % $ 55,000 $ — $ — $ — Debt discount, net (16,913 ) — — — Deferred financing costs, net (480 ) — — — Sunnova Energy Corporation Senior secured notes 10.02 % — — 14.89 % 40,000 — Convertible notes 13.34 % — — 12.20 % — 15,000 Notes payable 3.22 % — 2,428 — — Paid-in-kind — — 4,219 1,500 Deferred financing costs, net — — (38 ) — AP4 Secured term loan 5.61 % 86,369 6,109 5.25 % 101,026 3,036 Debt discount, net (452 ) — (202 ) — Deferred financing costs, net (196 ) — (418 ) — AP6WII Warehouse credit facility 10.01 % — — 8.47 % 54,603 — Deferred financing costs, net — — (309 ) — HELI Solar asset-backed notes 6.56 % 213,632 8,673 6.47 % 224,835 10,522 Debt discount, net (3,169 ) — (4,124 ) — Deferred financing costs, net (5,586 ) — (7,217 ) — LAPH Secured term loan 7.71 % 41,484 1,392 8.36 % 43,167 1,038 Debt discount, net (401 ) — (552 ) — Deferred financing costs, net (356 ) — (482 ) — EZOP Warehouse credit facility 6.60 % 121,400 — 9.68 % 58,200 — Debt discount, net (2,178 ) — — — TEPIH Secured term loan 25.17 % — — 6.55 % 107,239 3,356 Debt discount, net — — (62 ) — Deferred financing costs, net — — (4,892 ) — TEPIIH Revolving credit facility 6.36 % 234,650 — 8.41 % 57,552 — Debt discount, net (2,219 ) — (1,710 ) — Deferred financing costs, net — — (1,612 ) — HELII Solar asset-backed notes 5.77 % 241,309 13,005 5.60 % 253,687 9,013 Debt discount, net (49 ) — (55 ) — Deferred financing costs, net (5,873 ) — (6,425 ) — RAYSI Solar asset-backed notes 5.47 % 126,828 6,327 — — Debt discount, net (1,547 ) — — — Deferred financing costs, net (4,759 ) — — — HELIII Solar loan-backed notes 4.03 % 135,543 19,030 — — Debt discount, net (2,532 ) — — — Deferred financing costs, net (2,410 ) — — — TEPH Revolving credit facility 6.70 % 90,325 — — — Debt discount, net (645 ) — — — TEPINV Revolving credit facility 7.95 % 54,707 40,500 — — Debt discount, net (2,856 ) — — — Deferred financing costs, net (2,207 ) — — — Total $ 1,346,419 $ 97,464 $ 916,430 $ 43,465
Debt Instrument Redemption	We may, at our option, redeem for cash all or any portion of the convertible senior notes plus any accrued and unpaid interest to, but excluding, the redemption date at a redemption price equal to the following percentage of aggregate principal amount of convertible senior notes so redeemed: Period Percentage At any time prior to December 23, 2021 120% At any time on and after December 23, 2021 but prior to December 23, 2023 115% At any time on and after December 23, 2023 110%
Schedule of Carrying Values and Estimated Fair Values of Debt Instruments	Fair Values of Long-Term Debt . The fair values of our long-term debt and the corresponding carrying amounts are as follows: As of December 31, 2019 2018 Carrying Estimated Carrying Estimated (in thousands) SEI convertible senior notes $ 55,000 $ 37,964 $ — $ — Sunnova Energy Corporation senior secured notes — — 44,219 43,781 Sunnova Energy Corporation convertible notes — — 16,500 16,442 Sunnova Energy Corporation notes payable 2,428 2,428 — — AP4 secured term loan 92,478 92,478 104,062 104,062 AP6WII warehouse credit facility — — 54,603 54,603 HELI solar asset-backed notes 222,305 223,895 235,357 229,766 LAPH secured term loan 42,876 42,876 44,205 44,205 EZOP warehouse credit facility 121,400 121,400 58,200 58,200 TEPIH secured term loan — — 110,595 110,595 TEPIIH revolving credit facility 234,650 234,650 57,552 57,552 HELII solar asset-backed notes 254,314 281,850 262,700 274,857 RAYSI solar asset-backed notes 133,155 139,004 — — HELIII solar loan-backed notes 154,573 155,701 — — TEPH revolving credit facility 90,325 90,325 — — TEPINV revolving credit facility 95,207 95,207 — — Total (1) $ 1,498,711 $ 1,517,778 $ 987,993 $ 994,063 (1) Amounts exclude the net deferred financing costs and net debt discounts of $54.8 million and $28.1 million as of December 31, 2019 and 2018 , respectively.
Schedule of Maturities of Long-term Debt	As of December 31, 2019 , the principal maturities of our long-term debt were as follows: Principal Maturities (in thousands) 2020 $ 97,464 2021 154,285 2022 504,434 2023 74,649 2024 32,949 2025 and thereafter 634,930 Total $ 1,498,711

Derivative Instruments (Tables)

Derivative Instruments (Tables)	12 Months Ended
	Dec. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Outstanding Derivative Instruments	The following table presents a summary of the outstanding derivative instruments: As of December 31, 2019 2018 Effective Termination Fixed Aggregate Effective Termination Fixed Aggregate (in thousands, except interest rates) AP4 March 2018 July 2020 2.338% $ 99,762 March 2018 July 2020 2.338% $ 102,921 AP6WII —% — April 2019 April 2019 - 2.402% - 72,025 LAPH November 2018 October 2036 3.409% 43,298 November 2018 October 2036 3.409% 44,205 EZOP June 2019 - July 2029 - 1.631% - 100,083 March 2018 April 2019 - 1.900% - 55,290 TEPIH —% — June 2017 - April 2033 - 2.350% - 99,536 TEPIIH September 2018 July 2031 - 1.909% - 225,845 September 2018 - July 2031 - 2.995% - 54,675 TEPH September 2019 January 2023 1.620% - 55,115 —% — Total $ 524,103 $ 428,652
Fair Value of Interest Rate Swaps	The following table presents the fair value of the interest rate swaps as recorded in the consolidated balance sheets: As of December 31, 2019 2018 (in thousands) Other assets $ 360 $ 270 Other current liabilities (397 ) — Other long-term liabilities (27,092 ) (8,161 ) Total, net $ (27,129 ) $ (7,891 ) consolidated statements of operations: Year Ended 2019 2018 2017 (in thousands) Realized (gain) loss $ 13,195 $ (17,004 ) $ 3,295 Unrealized loss 19,237 6,100 5,944 Total $ 32,432 $ (10,904 ) $ 9,239

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation	Total income tax differs from the amounts computed by applying the statutory income tax rate to loss before income tax primarily as a result of our valuation allowance. The sources of these differences are as follows: Year Ended 2019 2018 2017 (in thousands) Loss before income tax $ (133,434 ) $ (68,409 ) $ (90,182 ) Statutory federal tax rate 21 % 21 % 35 % Tax benefit computed at statutory rate (28,021 ) (14,366 ) (31,564 ) State income tax, net of federal benefit (8,344 ) (4,308 ) (3,406 ) Adjustments from permanent differences: Enactment of the Tax Cuts and Jobs Act — — 6,118 Redeemable noncontrolling interests (2,293 ) (1,226 ) — ITC recapture 296 989 — Other 852 234 1,185 Increase in valuation allowance, net 37,510 18,677 27,667 Total income tax $ — $ — $ —
Schedule of Deferred Tax Assets and Liabilities	The tax effects of temporary differences that give rise to significant portions of the deferred tax assets (liabilities) are as follows: As of December 31, 2019 2018 (tax effected, in thousands) Federal net operating loss carryforward $ 169,379 $ 137,810 State net operating loss carryforward 49,565 38,659 ITC carryforward 246,828 226,378 Federal unused interest deduction carryforward 22,559 10,202 Investment in certain financing arrangements 36,999 16,374 Other deferred tax assets 20,801 11,531 Deferred tax assets 546,131 440,954 Fixed asset basis difference (235,510 ) (188,087 ) Investment in certain financing arrangements (22,826 ) (5,391 ) Other deferred tax liabilities (2,819 ) (874 ) Deferred tax liabilities (261,155 ) (194,352 ) Valuation allowance (284,976 ) (246,602 ) Net deferred tax asset $ — $ —

Details of Certain Subsidiary_2

Details of Certain Subsidiary Assets and Liabilities (Tables)	12 Months Ended
	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Details of Certain Subsidiary Assets and Liabilities	The following table presents the detail of assets and liabilities of certain subsidiaries as recorded in the consolidated balance sheet: As of December 31, 2019 Sunnova LAPH EZOP TEPH (in thousands) Assets Current assets: Cash $ 82,788 $ 1,323 $ 2,143 $ 14,672 Accounts receivable—trade, net 10,672 497 367 295 Accounts receivable, net—affiliates — — 78 — Accounts receivable—other 6,147 — — 4 Other current assets 174,016 172 5,314 47,388 Total current assets 273,623 1,992 7,902 62,359 Property and equipment, net 1,745,060 54,558 — 168,348 Customer notes receivable, net 297,975 — 125,950 — Other assets 169,712 1,815 6,629 5,564 Total assets $ 2,486,370 $ 58,365 $ 140,481 $ 236,271 Liabilities Current liabilities: Accounts payable $ 36,190 $ 14 $ 16 $ 247 Accounts payable, net—affiliates — 1,220 — 80,298 Accrued expenses 39,544 87 44 282 Current portion of long-term debt 97,464 1,392 — — Other current liabilities 21,720 818 165 697 Total current liabilities 194,918 3,531 225 81,524 Long-term debt, net 1,308,812 40,727 119,222 89,680 Other long-term liabilities 127,406 7,606 27,796 1,442 Total liabilities $ 1,631,136 $ 51,864 $ 147,243 $ 172,646

Equity-Based Compensation (Tabl

Equity-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Stock Option Assumptions	We used the following assumptions to apply the Black-Scholes option-pricing model to stock options granted during the years ended December 31, 2019 , 2018 and 2017 : Year Ended 2019 2018 2017 Expected dividend yield 0.00% 0.00% 0.00% Risk-free interest rate 2.62% 2.62% 2.11% Expected term (in years) 7.94 7.94 8.01 Volatility 81% 81% 68%
Stock Option Activity	The following table summarizes stock option activity: Number Weighted Weighted Weighted Aggregate (in thousands) Outstanding, December 31, 2017 3,166,008 $ 15.65 8.36 $ 124 Granted 1,834,876 $ 16.26 9.28 $ 3.52 Exercised (1,393 ) $ 1.85 $ 6 Forfeited (191,101 ) $ 15.23 $ 3.33 Outstanding, December 31, 2018 4,808,390 $ 15.90 8.09 $ 129 Granted 94,295 $ 13.58 9.07 $ 3.11 Exercised (2,143 ) $ 1.85 $ 20 Forfeited (596,233 ) $ 15.85 $ 3.48 Outstanding, December 31, 2019 4,304,309 $ 15.86 7.08 $ 242 Exercisable, December 31, 2019 3,339,913 $ 15.86 6.89 $ 242 Vested and expected to vest, December 31, 2019 4,304,309 $ 15.86 7.08 $ 242 Non-vested, December 31, 2018 3,124,367 $ 3.48 Non-vested, December 31, 2019 964,396 $ 3.52
Restricted Stock Unit Activity	The following table summarizes restricted stock unit activity: Number of Weighted Outstanding, December 31, 2018 — Granted 1,431,555 $ 11.93 Forfeited (5,416 ) $ 12.00 Outstanding, December 31, 2019 1,426,139 $ 11.93

Basic and Diluted Net Loss Pe_2

Basic and Diluted Net Loss Per Share (Tables)	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Schedule of Basic and Diluted Net Loss Per Share	The following table sets forth the computation of our basic and diluted net loss per share: Year Ended 2019 2018 2017 (in thousands, except share and per share amounts) Net loss attributable to stockholders $ (144,351 ) $ (74,246 ) $ (91,085 ) Dividends earned on Series A convertible preferred stock (19,271 ) (36,346 ) (29,623 ) Dividends earned on Series B convertible preferred stock — — (580 ) Dividends earned on Series C convertible preferred stock (5,454 ) (5,948 ) — Deemed dividends on convertible preferred stock exchange — (19,332 ) — Net loss attributable to common stockholders—basic and diluted $ (169,076 ) $ (135,872 ) $ (121,288 ) Net loss per share attributable to common stockholders—basic and diluted $ (4.14 ) $ (15.74 ) $ (14.05 ) Weighted average common shares outstanding—basic and diluted 40,797,976 8,634,477 8,632,936
Schedule of Antidilutive Weighted Average Shares	The following table presents the weighted average shares of common stock equivalents that were excluded from the computation of diluted net loss per share for the periods presented because including them would have been anti-dilutive: Year Ended 2019 2018 2017 Equity-based compensation awards 4,954,286 4,307,614 3,408,202 Convertible preferred stock 33,960,624 53,112,246 37,977,786 Convertible senior notes 104,320 — —

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Schedule of Performance Guarantee Obligations	The changes in our aggregate performance guarantee obligations are as follows: As of December 31, 2019 2018 (in thousands) Balance at beginning of period $ 6,044 $ 4,173 Accruals for obligations issued 3,101 3,033 Settlements made in cash (2,677 ) (1,162 ) Balance at end of period $ 6,468 $ 6,044
Lease Expense	The following table presents the detail of lease expense and lease income as recorded in general and administrative expense and other operating expense (income), respectively, in the consolidated statements of operations: Year Ended 2019 2018 2017 (in thousands) Operating lease expense $ 1,248 $ 972 $ 972 Finance lease amortization expense 8 — — Short-term lease expense 48 50 21 Variable lease expense 1,037 704 661 Sublease income (73 ) (70 ) (41 ) Total $ 2,268 $ 1,656 $ 1,613 Other information related to leases was as follows: Year Ended 2019 2018 2017 (in thousands) Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 1,254 $ 875 $ 814 Financing cash flows from finance leases 8 — — Right-of-use assets obtained in exchange for lease obligations: Operating leases 8,087 — 4,175 Finance leases 13 — — As of December 31, 2019 2018 Weighted average remaining lease term (years): Operating leases 9.41 3.42 Finance leases 0.68 — Weighted average discount rate: Operating leases 3.94 % 4.63 % Finance leases 4.26 % — %
Lease Assets And Liabilities	The following table presents the detail of right-of-use assets and lease liabilities as recorded in other assets and other current liabilities/other long-term liabilities, respectively, in the consolidated balance sheets: As of December 31, 2019 2018 (in thousands) Right-of-use assets: Operating leases $ 9,668 $ 2,586 Finance leases 5 — Total right-of-use assets $ 9,673 $ 2,586 Current lease liabilities: Operating leases $ 556 $ 871 Finance leases 5 — Long-term leases liabilities Operating leases 9,389 2,083 Total lease liabilities $ 9,950 $ 2,954
Finance Lease, Future Minimum Lease Payments	Future minimum lease payments under our non-cancelable leases as of December 31, 2019 were as follows: Operating Finance (in thousands) 2020 $ 1,037 $ 5 2021 1,536 — 2022 1,559 — 2023 1,594 — 2024 1,616 — 2025 and thereafter 7,617 — Total 14,959 5 Amount representing interest (2,603 ) — Amount representing leasehold incentives (2,411 ) — Present value of future payments 9,945 5 Current portion of lease liability (556 ) (5 ) Long-term portion of lease liability $ 9,389 $ —
Operating Lease, Future Minimum Lease Payments	Future minimum lease payments under our non-cancelable leases as of December 31, 2019 were as follows: Operating Finance (in thousands) 2020 $ 1,037 $ 5 2021 1,536 — 2022 1,559 — 2023 1,594 — 2024 1,616 — 2025 and thereafter 7,617 — Total 14,959 5 Amount representing interest (2,603 ) — Amount representing leasehold incentives (2,411 ) — Present value of future payments 9,945 5 Current portion of lease liability (556 ) (5 ) Long-term portion of lease liability $ 9,389 $ — Future minimum lease payments under our non-cancelable leases as of December 31, 2018 were as follows: Operating (in thousands) 2019 $ 989 2020 842 2021 863 2022 512 2023 — 2024 and thereafter — Total 3,206 Amount representing interest (252 ) Present value of future payments 2,954 Current portion of lease liability (871 ) Long-term portion of lease liability $ 2,083
Other Commitments	Dealer Commitments. As of December 31, 2019 , the net unamortized balance of payments to dealers for exclusivity and other similar arrangements was $32.8 million . Under these agreements, we paid $31.7 million during the year ended December 31, 2019 and could be obligated to make maximum payments, excluding additional amounts payable on a per watt basis if even higher thresholds are met, as follows: Dealer (in thousands) 2020 $ 24,184 2021 24,200 2022 25,240 2023 1,000 2024 — 2025 and thereafter — Total $ 74,624
Future Commitments	Future commitments as of December 31, 2019 were as follows: Information (in thousands) 2020 $ 4,962 2021 3,269 2022 10 2023 — 2024 — 2025 and thereafter — Total $ 8,241 Purchase Commitments. In August 2019, we amended an agreement with a supplier in which we agreed to purchase a minimum amount of energy storage systems for five years. These purchases are recorded to inventory within other current assets in the consolidated balance sheets. Under this agreement, we could be obligated to make minimum purchases as follows: Purchase (in thousands) 2020 $ 22,702 2021 27,359 2022 27,243 2023 27,053 2024 20,152 2025 and thereafter — Total $ 124,509

Selected Quarterly Financial _2

Selected Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Data	The following tables present the selected quarterly financial data for the years ended December 31, 2019 and 2018 . Three Months Ended December 31, 2019 September 30, 2019 June 30, 2019 March 31, 2019 (in thousands, except per share amounts) Revenue (1) $ 33,614 $ 36,615 $ 34,612 $ 26,715 Total operating expenses, net (1) $ 42,769 $ 42,513 $ 37,322 $ 31,222 Operating loss (1) $ (9,155 ) $ (5,898 ) $ (2,710 ) $ (4,507 ) Net loss (1)(2) $ (13,762 ) $ (34,369 ) $ (49,807 ) $ (35,496 ) Net loss attributable to common stockholders—basic and diluted (1)(2) $ (17,509 ) $ (37,590 ) $ (63,260 ) $ (50,717 ) Net loss per share attributable to common stockholders—basic and diluted (1)(2) $ (0.21 ) $ (0.62 ) $ (7.32 ) $ (5.87 ) Three Months Ended December 31, 2018 September 30, 2018 June 30, 2018 March 31, 2018 (in thousands, except per share amounts) Revenue (1) $ 25,206 $ 30,429 $ 28,963 $ 19,784 Total operating expenses, net (1)(3) $ 37,623 $ 27,025 $ 26,528 $ 26,936 Operating income (loss) (1)(3) $ (12,417 ) $ 3,404 $ 2,435 $ (7,152 ) Net loss (1)(2) $ (39,102 ) $ (6,647 ) $ (9,224 ) $ (13,436 ) Net loss attributable to common stockholders—basic and diluted (1)(2) $ (53,017 ) $ (17,865 ) $ (23,269 ) $ (41,721 ) Net loss per share attributable to common stockholders—basic and diluted (1)(2) $ (6.14 ) $ (2.07 ) $ (2.69 ) $ (4.83 ) (1) Fluctuations are primarily due to seasonality. (2) Fluctuations are primarily due to unrealized gains and losses on derivative instruments. (3) Fluctuations are primarily due to timing of estimates of losses from natural disasters and recoveries of business interruption insurance proceeds related to 2018.

Description of Business and B_2

Description of Business and Basis of Presentation - Narrative (Details) customer in Thousands	Jul. 29, 2019	Dec. 31, 2019customerstaterenewal_option
Subsidiary, Sale of Stock [Line Items]
Number of customers | customer		80
Number of states in which entity operates (more than) | state		20
Maximum renewal term		10 years
Reverse stock split ratio	0.4286
Lease and Power Purchase Agreement (PPA)
Subsidiary, Sale of Stock [Line Items]
Number of options to renew term | renewal_option		2
Renewal term		5 years
Minimum
Subsidiary, Sale of Stock [Line Items]
Agreement term		10 years
Maximum
Subsidiary, Sale of Stock [Line Items]
Agreement term		25 years

Significant Accounting Polici_4

Significant Accounting Policies - Narrative (Details)	12 Months Ended
	Dec. 31, 2019USD ($)kWhFICO_scoredealerrenewal_option	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Disaggregation of Revenue [Line Items]
Cash deposits in excess of FDIC insured limit	$ 72,400,000	$ 46,300,000
Restricted cash deposits in excess of FDIC insured limit	63,600,000	31,800,000
Accrued expenses for inventory purchases	$ 15,200,000
Number of dealers | dealer	100
Customer agreement, average term	23 years
Average age of solar systems	3 years
Inventory	$ 43,749,000	9,187,000
Note receivables not accruing interest	0	0
Notes receivable past due	151,000	81,000
Deferred revenue	58,853,000	34,048,000	$ 19,000,000
Revenue recognized	$ 3,000,000	2,000,000
Performance guarantee obligation term	P25Y
Performance guarantee obligation, initial payment period	3 years
Capitalization of interest term	4 months
Intangible assets, useful lives	3 years
Amortization, 2020	$ 29,000
Amortization, 2021	29,000
Amortization, 2022	9,000
Amortization, thereafter	0
Advertising expense	1,000,000	191,000	52,000
Defined contribution plan, employer contribution	736,000	551,000	458,000
Net loss on disposal and impairment expense	$ 1,772,000	7,565,000	$ 1,780,000
PPA revenue
Disaggregation of Revenue [Line Items]
Agreement term	25 years
Renewal term	5 years
Number of options to renew term | renewal_option	2
Lease revenue
Disaggregation of Revenue [Line Items]
Agreement term	25 years
Renewal term	5 years
Number of options to renew term | renewal_option	2
Remittances of customer payments, period after placed in service date	3 years
Solar renewable energy certificate revenue
Disaggregation of Revenue [Line Items]
Energy per certificate (in kWhs) | kWh	1,000
Typical period for receiving payment	1 month
Loan revenue
Disaggregation of Revenue [Line Items]
Deferred revenue	$ 46,958,000	27,793,000
Other revenue
Disaggregation of Revenue [Line Items]
Agreement term	5 years
Solar Renewable Energy Certificates
Disaggregation of Revenue [Line Items]
Inventory	$ 0	$ 0
Minimum
Disaggregation of Revenue [Line Items]
Agreement term	10 years
Warranty period	10 years
Minimum | Loan revenue
Disaggregation of Revenue [Line Items]
Agreement term	10 years
Minimum FICO score required for customer to qualify for program | FICO_score	650
Maximum
Disaggregation of Revenue [Line Items]
Agreement term	25 years
Warranty period	25 years
Maximum | PPA revenue
Disaggregation of Revenue [Line Items]
Renewal term	10 years
Maximum | Lease revenue
Disaggregation of Revenue [Line Items]
Renewal term	10 years
Maximum | Loan revenue
Disaggregation of Revenue [Line Items]
Agreement term	25 years
Minimum FICO score required for customer to qualify for program | FICO_score	720
Dealer One | Customer Concentration Risk | Expenditures
Disaggregation of Revenue [Line Items]
Concentration risk	49.00%	58.00%	32.00%
Dealer Two | Customer Concentration Risk | Expenditures
Disaggregation of Revenue [Line Items]
Concentration risk	10.00%		27.00%
Dealer Three | Customer Concentration Risk | Expenditures
Disaggregation of Revenue [Line Items]
Concentration risk			13.00%
Operations and maintenance expense
Disaggregation of Revenue [Line Items]
Net loss on disposal and impairment expense	$ 1,800,000	$ 7,400,000	$ 1,800,000
Natural disaster losses | Operations and maintenance expense
Disaggregation of Revenue [Line Items]
Net loss on disposal and impairment expense	$ 54,000	$ 5,800,000	$ 823,000

Significant Accounting Polici_5

Significant Accounting Policies - Restricted Cash (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	$ 66,806	$ 34,340
Restricted cash included in other current assets	10,474	5,190	$ 4,555
Debt and inverter reserves
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	55,407	28,225
Tax equity reserves
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	9,904	4,796
Letters of credit for office lease
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	725	725
Other
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	$ 770	$ 594

Significant Accounting Polici_6

Significant Accounting Policies - Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ 723	$ 427
Bad debt expense	1,645	1,119
Write off of uncollectible accounts	(1,498)	(861)
Recoveries	90	50
Other, net	0	(12)
Balance at end of period	$ 960	$ 723

Significant Accounting Polici_7

Significant Accounting Policies - Inventories (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Inventory [Line Items]
Inventory	$ 43,749	$ 9,187
Energy storage systems and components
Inventory [Line Items]
Inventory	33,443	8,394
Modules and inverters
Inventory [Line Items]
Inventory	10,137	433
Meters
Inventory [Line Items]
Inventory	$ 169	$ 360

Significant Accounting Polici_8

Significant Accounting Policies - Fair Value of Financial Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	$ 0	$ 0
Additions	55,506	0
Change in fair value	730	0
Extinguishment	(56,236)	0
Balance at end of period	$ 0	$ 0

Significant Accounting Polici_9

Significant Accounting Policies - Revenue (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Revenue	$ 33,614	$ 36,615	$ 34,612	$ 26,715	$ 25,206	$ 30,429	$ 28,963	$ 19,784	$ 131,556	$ 104,382	$ 76,856
PPA revenue
Disaggregation of Revenue [Line Items]
Revenue									48,041	38,950	29,171
Lease revenue
Disaggregation of Revenue [Line Items]
Revenue									40,191	33,079	21,866
Solar renewable energy certificate revenue
Disaggregation of Revenue [Line Items]
Revenue									38,453	30,630	24,833
Loan revenue
Disaggregation of Revenue [Line Items]
Revenue									1,645	933	479
Other revenue
Disaggregation of Revenue [Line Items]
Revenue									$ 3,226	$ 790	$ 507

Significant Accounting Polic_10

Significant Accounting Policies - Performance Obligations (Details) $ in Billions	12 Months Ended
	Dec. 31, 2019USD ($)
Accounting Policies [Abstract]
Contracted but not yet recognized revenue	$ 1.1
Performance obligation, description of timing	We do not expect the annual recognition to vary significantly over approximately the next 20 years as the vast majority of existing solar service agreements have at least 20 years remaining
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-12-31
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Contracted but not yet recognized revenue, percentage	4.00%
Contracted but not yet recognized revenue, expected timing of satisfaction	12 months

Significant Accounting Polic_11

Significant Accounting Policies - Customer Notes Receivable (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ 710	$ 602
Bad debt expense	419	238
Write off of uncollectible accounts	(38)	(130)
Balance at end of period	$ 1,091	$ 710

Significant Accounting Polic_12

Significant Accounting Policies - Deferred Revenue (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Deferred revenue	$ 58,853	$ 34,048	$ 19,000
Deferred revenue included in other current liabilities	2,086	1,593
Loans
Disaggregation of Revenue [Line Items]
Deferred revenue	46,958	27,793
PPAs and leases
Disaggregation of Revenue [Line Items]
Deferred revenue	8,895	6,255
SRECs
Disaggregation of Revenue [Line Items]
Deferred revenue	$ 3,000	$ 0

Significant Accounting Polic_13

Significant Accounting Policies - Intangibles Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Intangible assets	$ 487	$ 399
Less: accumulated amortization	(420)	(399)
Intangibles, net	67	0
Software license
Finite-Lived Intangible Assets [Line Items]
Intangible assets	331	331
Trademark
Finite-Lived Intangible Assets [Line Items]
Intangible assets	68	68
Other
Finite-Lived Intangible Assets [Line Items]
Intangible assets	$ 88	$ 0

Significant Accounting Polic_14

Significant Accounting Policies - Deferred Financing Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Debt Issuance Costs [Roll Forward]
Balance at beginning of period	$ 22,712	$ 25,188
Capitalized	12,731	6,598
Amortized	(9,822)	(9,074)	$ (14,568)
Balance at end of period	$ 25,621	$ 22,712	$ 25,188

Property and Equipment (Details

Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2017	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 1,893,219		$ 1,427,535
Less: accumulated depreciation	(148,159)		(99,078)
Property and equipment, net	$ 1,745,060		1,328,457
Capitalized interest costs		$ 216
Solar energy systems
Property, Plant and Equipment [Line Items]
Useful Lives	35 years
Property and equipment, gross	$ 1,689,457		1,311,458
Less: accumulated depreciation	(130,900)		(87,600)
Construction in progress
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 143,449		77,847
AROs
Property, Plant and Equipment [Line Items]
Useful Lives	30 years
Property and equipment, gross	$ 26,967		17,381
Information technology systems
Property, Plant and Equipment [Line Items]
Useful Lives	3 years
Property and equipment, gross	$ 28,320		17,380
Computers and equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 1,499		1,251
Computers and equipment | Minimum
Property, Plant and Equipment [Line Items]
Useful Lives	3 years
Computers and equipment | Maximum
Property, Plant and Equipment [Line Items]
Useful Lives	5 years
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 1,014		883
Leasehold improvements | Minimum
Property, Plant and Equipment [Line Items]
Useful Lives	3 years
Leasehold improvements | Maximum
Property, Plant and Equipment [Line Items]
Useful Lives	6 years
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Useful Lives	7 years
Property and equipment, gross	$ 735		735
Vehicles
Property, Plant and Equipment [Line Items]
Useful Lives	4 years
Property and equipment, gross	$ 1,632		548
Other
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 146		$ 52
Other | Minimum
Property, Plant and Equipment [Line Items]
Useful Lives	5 years
Other | Maximum
Property, Plant and Equipment [Line Items]
Useful Lives	6 years

Natural Disaster Losses (Detail

Natural Disaster Losses (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)
Business Interruption Loss [Line Items]
Insurance proceeds	$ 9.8
Solar Energy System Damage
Business Interruption Loss [Line Items]
Insurance proceeds	5.8
Recoveries for Business Interruption
Business Interruption Loss [Line Items]
Insurance proceeds	$ 4

Natural Disaster Losses - Sched

Natural Disaster Losses - Schedule of Disaster Losses (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Business Interruption Loss [Line Items]
Operations and maintenance									$ 8,588	$ 14,035	$ 4,994
General and administrative									97,986	67,430	54,863
Total operating expense, net	$ 42,769	$ 42,513	$ 37,322	$ 31,222	$ 37,623	$ 27,025	$ 26,528	$ 26,936	153,826	118,112	87,211
Natural disaster losses
Business Interruption Loss [Line Items]
Total operating expense, net									54	5,523	(273)
Impairment of solar energy systems due to natural disaster losses
Business Interruption Loss [Line Items]
Operations and maintenance									0	5,840	6,745
Insurance proceeds received/expected to be received—property damage
Business Interruption Loss [Line Items]
Operations and maintenance									54	(53)	(5,922)
Insurance proceeds received—business interruption
Business Interruption Loss [Line Items]
Operations and maintenance									0	(2,693)	(1,307)
Other natural disaster-related charges
Business Interruption Loss [Line Items]
Operations and maintenance									0	1,679	65
General and administrative									$ 0	$ 750	$ 146

Detail of Certain Balance She_3

Detail of Certain Balance Sheet Captions - Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Prepaid inventory	$ 96,167	$ 0
Inventory	43,749	9,187
Current portion of customer notes receivable	13,758	7,601
Other prepaid assets	7,380	2,739
Current portion of other notes receivable	982	1,522
Deferred receivables	1,506	555
Restricted cash	10,474	5,190	$ 4,555
Total	$ 174,016	$ 26,794

Detail of Certain Balance She_4

Detail of Certain Balance Sheet Captions - Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Interest payable	$ 14,680	$ 8,150
Current portion of performance guarantee obligations	4,067	2,580
Current portion of lease liability	561	871
Deferred revenue	2,086	1,593
Other	410	20
Total	$ 21,804	$ 13,214

AROs (Details)

AROs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Asset Retirement Obligation Disclosure [Abstract]
Asset retirement obligation, useful life	30 years
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	$ 20,033	$ 15,347
Additional obligations incurred	4,641	3,607
Accretion expense	1,443	1,183
Change in estimate	4,983	0
Other	(47)	(104)
Balance at end of period	$ 31,053	$ 20,033

Customer Notes Receivable - Nar

Customer Notes Receivable - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current portion of notes receivable	$ 13,758	$ 7,601
Customer notes receivable, net	297,975	172,031
Loan systems not yet placed in service	37,100	20,400
Interest income	12,483	6,450	$ 3,197
Customer Notes Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable	311,700	179,600
Current portion of notes receivable	13,800	7,600
Customer notes receivable, net	298,000	172,000
Interest income	$ 11,600	$ 6,100	$ 3,000
Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Agreement term	10 years
Minimum | Loan revenue
Accounts, Notes, Loans and Financing Receivable [Line Items]
Agreement term	10 years
Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Agreement term	25 years
Maximum | Loan revenue
Accounts, Notes, Loans and Financing Receivable [Line Items]
Agreement term	25 years

Customer Notes Receivable - Fai

Customer Notes Receivable - Fair Value of Customer Notes Receivable (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Carrying Value
Accounts, Notes, Loans and Financing Receivable [Line Items]
Customer notes receivable	$ 311,732	$ 179,632
Estimated Fair Value
Accounts, Notes, Loans and Financing Receivable [Line Items]
Customer notes receivable	$ 314,222	$ 179,990

Long-Term Debt - Schedule of Lo

Long-Term Debt - Schedule of Long-Term Debt (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Long-term debt, non-current	$ 1,346,419	$ 916,430
Long-term debt, current	97,464	43,465
SEI
Debt Instrument [Line Items]
Debt discount, net, non-current	(16,913)	0
Deferred financing costs, net, non-current	(480)	0
Debt discount, net, current	0	0
Deferred financing costs, net, current	$ 0	0
SEI | Convertible senior notes
Debt Instrument [Line Items]
Weighted average effective interest rates	7.75%
Long-term debt, gross, non-current	$ 55,000	0
Long-term debt, gross, current	0	0
Sunnova Energy Corporation
Debt Instrument [Line Items]
Deferred financing costs, net, non-current	0	(38)
Deferred financing costs, net, current	$ 0	$ 0
Sunnova Energy Corporation | Senior secured notes
Debt Instrument [Line Items]
Weighted average effective interest rates	10.02%	14.89%
Long-term debt, gross, non-current	$ 0	$ 40,000
Long-term debt, gross, current	$ 0	$ 0
Sunnova Energy Corporation | Convertible notes
Debt Instrument [Line Items]
Weighted average effective interest rates	13.34%	12.20%
Long-term debt, gross, non-current	$ 0	$ 0
Long-term debt, gross, current	$ 0	15,000
Sunnova Energy Corporation | Notes payable
Debt Instrument [Line Items]
Weighted average effective interest rates	3.22%
Long-term debt, gross, non-current	$ 0	0
Long-term debt, gross, current	2,428	0
Sunnova Energy Corporation | Paid-in-kind
Debt Instrument [Line Items]
Long-term debt, gross, non-current	0	4,219
Long-term debt, gross, current	0	1,500
AP4
Debt Instrument [Line Items]
Debt discount, net, non-current	(452)	(202)
Deferred financing costs, net, non-current	(196)	(418)
Debt discount, net, current	0	0
Deferred financing costs, net, current	$ 0	$ 0
AP4 | Secured term loan
Debt Instrument [Line Items]
Weighted average effective interest rates	5.61%	5.25%
Long-term debt, gross, non-current	$ 86,369	$ 101,026
Long-term debt, gross, current	6,109	3,036
AP6WII
Debt Instrument [Line Items]
Deferred financing costs, net, non-current	0	(309)
Deferred financing costs, net, current	$ 0	$ 0
AP6WII | Warehouse credit facility
Debt Instrument [Line Items]
Weighted average effective interest rates	10.01%	8.47%
Long-term debt, gross, non-current	$ 0	$ 54,603
Long-term debt, gross, current	0	0
HELI
Debt Instrument [Line Items]
Debt discount, net, non-current	(3,169)	(4,124)
Deferred financing costs, net, non-current	(5,586)	(7,217)
Debt discount, net, current	0	0
Deferred financing costs, net, current	$ 0	$ 0
HELI | Solar asset-backed notes
Debt Instrument [Line Items]
Weighted average effective interest rates	6.56%	6.47%
Long-term debt, gross, non-current	$ 213,632	$ 224,835
Long-term debt, gross, current	8,673	10,522
LAPH
Debt Instrument [Line Items]
Debt discount, net, non-current	(401)	(552)
Deferred financing costs, net, non-current	(356)	(482)
Debt discount, net, current	0	0
Deferred financing costs, net, current	$ 0	$ 0
LAPH | Secured term loan
Debt Instrument [Line Items]
Weighted average effective interest rates	7.71%	8.36%
Long-term debt, gross, non-current	$ 41,484	$ 43,167
Long-term debt, gross, current	1,392	1,038
EZOP
Debt Instrument [Line Items]
Debt discount, net, non-current	(2,178)	0
Debt discount, net, current	$ 0	$ 0
EZOP | Warehouse credit facility
Debt Instrument [Line Items]
Weighted average effective interest rates	6.60%	9.68%
Long-term debt, gross, non-current	$ 121,400	$ 58,200
Long-term debt, gross, current	0	0
TEPIH
Debt Instrument [Line Items]
Debt discount, net, non-current	0	(62)
Deferred financing costs, net, non-current	0	(4,892)
Debt discount, net, current	0	0
Deferred financing costs, net, current	$ 0	$ 0
TEPIH | Secured term loan
Debt Instrument [Line Items]
Weighted average effective interest rates	25.17%	6.55%
Long-term debt, gross, non-current	$ 0	$ 107,239
Long-term debt, gross, current	0	3,356
TEPIIH
Debt Instrument [Line Items]
Debt discount, net, non-current	(2,219)	(1,710)
Deferred financing costs, net, non-current	0	(1,612)
Debt discount, net, current	0	0
Deferred financing costs, net, current	$ 0	$ 0
TEPIIH | Line of credit | Revolving credit facility
Debt Instrument [Line Items]
Weighted average effective interest rates	6.36%	8.41%
Long-term debt, gross, non-current	$ 234,650	$ 57,552
Long-term debt, gross, current	0	0
HELII
Debt Instrument [Line Items]
Debt discount, net, non-current	(49)	(55)
Deferred financing costs, net, non-current	(5,873)	(6,425)
Debt discount, net, current	0	0
Deferred financing costs, net, current	$ 0	$ 0
HELII | Solar asset-backed notes
Debt Instrument [Line Items]
Weighted average effective interest rates	5.77%	5.60%
Long-term debt, gross, non-current	$ 241,309	$ 253,687
Long-term debt, gross, current	13,005	9,013
RAYSI
Debt Instrument [Line Items]
Debt discount, net, non-current	(1,547)	0
Deferred financing costs, net, non-current	(4,759)	0
Debt discount, net, current	0	0
Deferred financing costs, net, current	$ 0	0
RAYSI | Solar asset-backed notes
Debt Instrument [Line Items]
Weighted average effective interest rates	5.47%
Long-term debt, gross, non-current	$ 126,828	0
Long-term debt, gross, current	6,327	0
HELIII
Debt Instrument [Line Items]
Debt discount, net, non-current	(2,532)	0
Deferred financing costs, net, non-current	(2,410)	0
Debt discount, net, current	0	0
Deferred financing costs, net, current	$ 0	0
HELIII | Solar loan-backed notes
Debt Instrument [Line Items]
Weighted average effective interest rates	4.03%
Long-term debt, gross, non-current	$ 135,543	0
Long-term debt, gross, current	19,030	0
TEPH
Debt Instrument [Line Items]
Debt discount, net, non-current	(645)	0
Debt discount, net, current	$ 0	0
TEPH | Line of credit | Revolving credit facility
Debt Instrument [Line Items]
Weighted average effective interest rates	6.70%
Long-term debt, gross, non-current	$ 90,325	0
Long-term debt, gross, current	0	0
TEPINV
Debt Instrument [Line Items]
Debt discount, net, non-current	(2,856)	0
Deferred financing costs, net, non-current	(2,207)	0
Debt discount, net, current	0	0
Deferred financing costs, net, current	$ 0	0
TEPINV | Line of credit | Revolving credit facility
Debt Instrument [Line Items]
Weighted average effective interest rates	7.95%
Long-term debt, gross, non-current	$ 54,707	0
Long-term debt, gross, current	$ 40,500	$ 0

Long-Term Debt - Narrative (Det

Long-Term Debt - Narrative (Details)

Jul. 29, 2019USD ($)shares

Dec. 31, 2019USD ($)$ / shares

Jul. 31, 2019USD ($)

Jun. 30, 2019USD ($)$ / shares

May 31, 2019USD ($)

Apr. 30, 2019USD ($)

Mar. 31, 2019USD ($)

Nov. 30, 2018USD ($)

Dec. 31, 2017USD ($)

Nov. 30, 2017USD ($)

Jun. 30, 2017USD ($)

Apr. 30, 2017USD ($)

Mar. 31, 2017USD ($)

Dec. 31, 2016

Mar. 31, 2019USD ($)

Dec. 31, 2019USD ($)$ / shares

Dec. 31, 2018USD ($)

Dec. 31, 2017USD ($)

Aug. 31, 2018USD ($)

Mar. 31, 2018USD ($)$ / shares

Oct. 31, 2017USD ($)

Aug. 31, 2017USD ($)

Apr. 30, 2016USD ($)

Oct. 31, 2015USD ($)

Jul. 31, 2014USD ($)

Debt Instrument [Line Items]

Carrying amount

$ 1,498,711,000

$ 1,498,711,000

Loss on extinguishment of debt

10,645,000

$ 0

$ 0

Unrealized loss on fair value election

150,000

0

0

Property and equipment, gross

1,893,219,000

1,893,219,000

1,427,535,000

Solar energy systems

Debt Instrument [Line Items]

Property and equipment, gross

1,689,457,000

1,689,457,000

$ 1,311,458,000

Warehouse credit facility

Debt Instrument [Line Items]

Borrowing capacity

88,300,000

88,300,000

SEI | Convertible senior notes

Debt Instrument [Line Items]

Principal amount of debt issued

55,000,000

55,000,000

Additional borrowing capacity

$ 20,000,000

$ 20,000,000

Stated interest rate

7.75%

7.75%

Registration requirement period

90 days

Conversion ratio

0.0769231

Conversion price (in USD per share) | $ / shares

$ 13

$ 13

Carrying amount

$ 37,600,000

$ 37,600,000

Unamortized debt discount

16,900,000

16,900,000

Unamortized issuance costs

480,000

480,000

Equity component of debt instrument

14,000,000

14,000,000

Equity component, unamortized issuance costs

179,000

179,000

Sunnova Energy Corporation

Debt Instrument [Line Items]

Debt Instrument, Covenant, Aggregate Capital Commitment, Year One

$ 40,000,000

Capital commitment

$ 80,000,000

Sunnova Energy Corporation | Senior secured notes

Debt Instrument [Line Items]

Principal amount of debt issued

$ 56,200,000

Stated interest rate

9.50%

12.00%

Percent of cash payable quarterly

4.75%

6.00%

Percent of payment-in-kind quarterly

4.75%

6.00%

Minimum liquidity

$ 8,000,000

Loss on extinguishment of debt

$ 10,600,000

Repayment of long-term debt

$ 57,100,000

Unrealized loss on fair value election

730,000

Sunnova Energy Corporation | Convertible notes

Debt Instrument [Line Items]

Principal amount of debt issued

$ 15,000,000

Stated interest rate

12.00%

Sunnova Energy Corporation | Notes payable

Debt Instrument [Line Items]

Principal amount of debt issued

$ 4,700,000

$ 1,900,000

Stated interest rate

4.94%

5.50%

Term

8 months

10 months

Sunnova Energy Corporation | 12.0% Due in October 2018 | Senior secured notes

Debt Instrument [Line Items]

Principal amount of debt issued

80,000,000

AP4

Debt Instrument [Line Items]

Equity cure contribution

$ 106,000

AP4 | Secured term loan

Debt Instrument [Line Items]

Principal amount of debt issued

$ 107,100,000

$ 107,100,000

$ 110,000,000

$ 90,000,000

Repayment of long-term debt

$ 5,000,000

Commitment fee

0.50%

Debt service coverage ratio, minimum

1.25

Debt service coverage ratio, minimum for distributions

1

AP6WII | Warehouse credit facility

Debt Instrument [Line Items]

Maximum commitment amount

$ 175,000,000

HELI | Solar energy systems

Debt Instrument [Line Items]

Property and equipment, gross

296,800,000

296,800,000

HELI | Solar Loan-Backed Notes, 2017-1 Class A | Solar asset-backed notes

Debt Instrument [Line Items]

Principal amount of debt issued

$ 191,800,000

Stated interest rate

4.94%

Discount percent

0.05%

HELI | Solar Loan-Backed Notes, 2017-1 Class B | Solar asset-backed notes

Debt Instrument [Line Items]

Principal amount of debt issued

$ 18,000,000

Stated interest rate

6.00%

Discount percent

9.28%

HELI | Solar Loan-Backed Notes, 2017-1 Class C | Solar asset-backed notes

Debt Instrument [Line Items]

Principal amount of debt issued

$ 45,000,000

Stated interest rate

8.00%

Discount percent

8.65%

LAPH | Secured term loan

Debt Instrument [Line Items]

Principal amount of debt issued

$ 260,000,000

LAPH | Class A advances | Secured term loan

Debt Instrument [Line Items]

Principal amount of debt issued

$ 44,200,000

Applicable margin rate

3.30%

LAPH | Class B advances | Secured term loan

Debt Instrument [Line Items]

Principal amount of debt issued

0

Applicable margin rate

11.00%

EZOP | Warehouse credit facility

Debt Instrument [Line Items]

Borrowing capacity

78,600,000

78,600,000

Maximum commitment amount

$ 200,000,000

$ 100,000,000

$ 200,000,000

$ 70,000,000

TEPIH

Debt Instrument [Line Items]

Capital commitment

$ 97,500,000

$ 91,100,000

$ 80,000,000

TEPIH | Secured term loan

Debt Instrument [Line Items]

Term

5 years

Maximum commitment amount

$ 140,000,000

Required initial borrowing

$ 15,000,000

HELII | Solar energy systems

Debt Instrument [Line Items]

Property and equipment, gross

$ 330,900,000

$ 330,900,000

HELII | Asset-backed Securities, 2019-01 Class A | Solar asset-backed notes

Debt Instrument [Line Items]

Principal amount of debt issued

$ 202,000,000

Stated interest rate

4.87%

Discount percent

0.02%

HELII | Asset-backed Securities, 2019-01 Class B | Solar asset-backed notes

Debt Instrument [Line Items]

Principal amount of debt issued

$ 60,700,000

Stated interest rate

7.71%

Discount percent

0.02%

RAYSI | Asset-backed Securities, 2019-01 Class A | Solar asset-backed notes

Debt Instrument [Line Items]

Principal amount of debt issued

$ 118,100,000

$ 118,100,000

Stated interest rate

4.95%

4.95%

Discount percent

0.00%

RAYSI | Asset-backed Securities, 2019-01 Class B | Solar asset-backed notes

Debt Instrument [Line Items]

Principal amount of debt issued

$ 15,000,000

$ 15,000,000

Stated interest rate

6.35%

6.35%

Discount percent

6.50%

RAYSI | Asset-backed Securities, 2019-02 Class B | Solar asset-backed notes

Debt Instrument [Line Items]

Principal amount of debt issued

$ 6,400,000

Stated interest rate

6.35%

Discount percent

10.50%

HELIII | Solar loan-backed notes, 2019-A Class A

Debt Instrument [Line Items]

Principal amount of debt issued

$ 139,700,000

Stated interest rate

3.75%

Discount percent

0.03%

HELIII | Solar loan-backed notes, 2019-A Class B

Debt Instrument [Line Items]

Principal amount of debt issued

$ 14,900,000

Stated interest rate

4.49%

Discount percent

0.01%

HELIII | Solar loan-backed notes, 2019-A Class C

Debt Instrument [Line Items]

Principal amount of debt issued

$ 13,000,000

Stated interest rate

5.32%

Discount percent

0.03%

London Interbank Offered Rate (LIBOR) | AP4 | Secured term loan

Debt Instrument [Line Items]

Applicable margin rate

2.50%

3.00%

London Interbank Offered Rate (LIBOR) | LAPH | Class A advances | Secured term loan

Debt Instrument [Line Items]

Applicable margin rate

4.50%

London Interbank Offered Rate (LIBOR) | TEPIH | Secured term loan

Debt Instrument [Line Items]

Applicable margin rate

1.00%

Federal Funds Rate | TEPIH | Secured term loan

Debt Instrument [Line Items]

Applicable margin rate

0.50%

Minimum | SEI | Convertible senior notes

Debt Instrument [Line Items]

Additional interest rate

0.25%

0.25%

Minimum | London Interbank Offered Rate (LIBOR) | EZOP | Warehouse credit facility

Debt Instrument [Line Items]

Applicable margin rate

2.35%

2.15%

Maximum | SEI | Convertible senior notes

Debt Instrument [Line Items]

Additional interest rate

2.00%

2.00%

Maximum | London Interbank Offered Rate (LIBOR) | EZOP | Warehouse credit facility

Debt Instrument [Line Items]

Applicable margin rate

3.35%

3.15%

Series A convertible preferred stock

Debt Instrument [Line Items]

Convertible preferred stock price (in USD per share) | $ / shares

$ 5.3246735

2018 Note Conversion | Series A convertible preferred stock

Debt Instrument [Line Items]

Shares issued upon debt conversion (in shares) | shares

3,319,312

2019 Note Conversion | Sunnova Energy Corporation | Convertible notes

Debt Instrument [Line Items]

Principal amount of debt issued

$ 15,000,000

Stated interest rate

12.00%

Conversion price (in USD per share) | $ / shares

$ 5.80

2019 Note Conversion | Series C convertible preferred stock

Debt Instrument [Line Items]

Shares issued upon debt conversion (in shares) | shares

2,613,818

Common Stock

Debt Instrument [Line Items]

Shares issued in conversion of stock (in shares) | shares

60,479,017

Common Stock | 2018 Note Conversion

Debt Instrument [Line Items]

Shares issued in conversion of stock (in shares) | shares

1,422,767

Common Stock | 2019 Note Conversion

Debt Instrument [Line Items]

Shares issued in conversion of stock (in shares) | shares

1,120,360

Energy Capital Partners

Debt Instrument [Line Items]

Preferred stock commitment

$ 28,200,000

Redemption Period One | SEI | Convertible senior notes

Debt Instrument [Line Items]

Redemption price

120.00%

Redemption Period Two | SEI | Convertible senior notes

Debt Instrument [Line Items]

Redemption price

115.00%

Redemption Period Three | SEI | Convertible senior notes

Debt Instrument [Line Items]

Redemption price

110.00%

Redemption Period Four | SEI | Convertible senior notes

Debt Instrument [Line Items]

Redemption price

110.00%

Variable rate componente, adjusted | AP4 | Secured term loan

Debt Instrument [Line Items]

Applicable margin rate

2.00%

Variable rate componente, adjusted | London Interbank Offered Rate (LIBOR) | AP4 | Secured term loan

Debt Instrument [Line Items]

Applicable margin rate

1.00%

Variable rate componente, adjusted | Federal Funds Rate | AP4 | Secured term loan

Debt Instrument [Line Items]

Applicable margin rate

0.50%

Rate multiplier one | AP6WII | Warehouse credit facility

Debt Instrument [Line Items]

Interest rate multiplier

5.00%

Rate multiplier two | AP6WII | Warehouse credit facility

Debt Instrument [Line Items]

Interest rate multiplier

4.25%

Prior period commitments, period

12 months

Rate multiplier three | AP6WII | Warehouse credit facility

Debt Instrument [Line Items]

Interest rate multiplier

5.50%

Rate multiplier four | AP6WII | Warehouse credit facility

Debt Instrument [Line Items]

Interest rate multiplier

4.75%

During commitment availability period | Weighted-Average Cost to Lender Rate | EZOP | Warehouse credit facility

Debt Instrument [Line Items]

Applicable margin rate

3.50%

After commitment availability period | Weighted-Average Cost to Lender Rate | EZOP | Warehouse credit facility

Debt Instrument [Line Items]

Applicable margin rate

4.50%

Inception through last day of availability period | London Interbank Offered Rate (LIBOR) | TEPIH | Secured term loan

Debt Instrument [Line Items]

Applicable margin rate

3.00%

Inception through last day of availability period | Base Rate | TEPIH | Secured term loan

Debt Instrument [Line Items]

Applicable margin rate

2.00%

Last day of availability period through three year anniversary | London Interbank Offered Rate (LIBOR) | TEPIH | Secured term loan

Debt Instrument [Line Items]

Applicable margin rate

3.25%

Last day of availability period through three year anniversary | Base Rate | TEPIH | Secured term loan

Debt Instrument [Line Items]

Applicable margin rate

2.25%

Three year anniversary to last day of availability | London Interbank Offered Rate (LIBOR) | TEPIH | Secured term loan

Debt Instrument [Line Items]

Applicable margin rate

3.50%

Three year anniversary to last day of availability | Base Rate | TEPIH | Secured term loan

Debt Instrument [Line Items]

Applicable margin rate

2.50%

Revolving credit facility | TEPIIH | Line of credit

Debt Instrument [Line Items]

Maximum commitment amount

$ 250,000,000

$ 250,000,000

$ 175,000,000

Aggregate committed amount

$ 150,000,000

$ 150,000,000

$ 125,000,000

Revolving credit facility | TEPH | Line of credit

Debt Instrument [Line Items]

Borrowing capacity

$ 9,700,000

$ 9,700,000

Maximum commitment amount

150,000,000

150,000,000

Aggregate committed amount

$ 100,000,000

$ 100,000,000

Revolving credit facility | TEPINV | Line of credit

Debt Instrument [Line Items]

Term

27 months

Applicable margin rate

0.00%

Maximum commitment amount

$ 137,600,000

$ 137,600,000

Aggregate committed amount

95,200,000

$ 95,200,000

Revolving credit facility | London Interbank Offered Rate (LIBOR) | TEPIIH | Line of credit

Debt Instrument [Line Items]

Variable rate calculation percentage

100.00%

Revolving credit facility | Federal Funds Rate | TEPIIH | Line of credit

Debt Instrument [Line Items]

Applicable margin rate

0.50%

Revolving credit facility | Federal Funds Rate | TEPH | Line of credit

Debt Instrument [Line Items]

Variable rate basis adjustment

0.50%

Revolving credit facility | Federal Funds Rate | TEPINV | Line of credit

Debt Instrument [Line Items]

Applicable margin rate

0.50%

Obligation cap, percent

10.00%

Revolving credit facility | Federal Funds Rate | TEPINV | Class A Loans | Line of credit

Debt Instrument [Line Items]

Applicable margin rate

5.99%

Revolving credit facility | Minimum | TEPH | Line of credit

Debt Instrument [Line Items]

Applicable margin rate

2.90%

Revolving credit facility | Maximum | TEPH | Line of credit

Debt Instrument [Line Items]

Applicable margin rate

4.30%

Revolving credit facility | Solar Projects Before Construction | TEPH | Line of credit

Debt Instrument [Line Items]

Advanced rate

60.00%

Revolving credit facility | Solar Projects Under Construction | TEPH | Line of credit

Debt Instrument [Line Items]

Advanced rate

80.00%

Revolving credit facility | Eligible Projects | TEPINV | Line of credit

Debt Instrument [Line Items]

Advanced rate

85.00%

Obligation cap

$ 9,500,000

$ 9,500,000

Long-Term Debt - Redemption Rat

Long-Term Debt - Redemption Rate (Details) - SEI - Convertible senior notes	12 Months Ended
	Dec. 31, 2019
At any time prior to December 23, 2021
Debt Instrument, Redemption [Line Items]
Redemption price	120.00%
At any time on and after December 23, 2021 but prior to December 23, 2023
Debt Instrument, Redemption [Line Items]
Redemption price	115.00%
At any time on and after December 23, 2023
Debt Instrument, Redemption [Line Items]
Redemption price	110.00%
On and after September 23, 2024
Debt Instrument, Redemption [Line Items]
Redemption price	110.00%

Long-Term Debt - Schedule of Fa

Long-Term Debt - Schedule of Fair Value of Long-term Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Net deferred financing costs and debt discounts	$ 54,800	$ 28,100
Carrying Value
Debt Instrument [Line Items]
Long-term debt	1,498,711	987,993
Estimated Fair Value
Debt Instrument [Line Items]
Long-term debt	1,517,778	994,063
SEI | Carrying Value | Convertible senior notes
Debt Instrument [Line Items]
Long-term debt	55,000	0
SEI | Estimated Fair Value | Convertible senior notes
Debt Instrument [Line Items]
Long-term debt	37,964	0
Sunnova Energy Corporation | Carrying Value | Senior secured notes
Debt Instrument [Line Items]
Long-term debt	0	44,219
Sunnova Energy Corporation | Carrying Value | Convertible notes
Debt Instrument [Line Items]
Long-term debt	0	16,500
Sunnova Energy Corporation | Carrying Value | Notes payable
Debt Instrument [Line Items]
Long-term debt	2,428	0
Sunnova Energy Corporation | Estimated Fair Value | Senior secured notes
Debt Instrument [Line Items]
Long-term debt	0	43,781
Sunnova Energy Corporation | Estimated Fair Value | Convertible notes
Debt Instrument [Line Items]
Long-term debt	0	16,442
Sunnova Energy Corporation | Estimated Fair Value | Notes payable
Debt Instrument [Line Items]
Long-term debt	2,428	0
AP4 | Carrying Value | Secured term loan
Debt Instrument [Line Items]
Long-term debt	92,478	104,062
AP4 | Estimated Fair Value | Secured term loan
Debt Instrument [Line Items]
Long-term debt	92,478	104,062
AP6WII | Carrying Value | Warehouse credit facility
Debt Instrument [Line Items]
Long-term debt	0	54,603
AP6WII | Estimated Fair Value | Warehouse credit facility
Debt Instrument [Line Items]
Long-term debt	0	54,603
HELI | Carrying Value | Solar asset-backed notes
Debt Instrument [Line Items]
Long-term debt	222,305	235,357
HELI | Estimated Fair Value | Solar asset-backed notes
Debt Instrument [Line Items]
Long-term debt	223,895	229,766
LAPH | Carrying Value | Secured term loan
Debt Instrument [Line Items]
Long-term debt	42,876	44,205
LAPH | Estimated Fair Value | Secured term loan
Debt Instrument [Line Items]
Long-term debt	42,876	44,205
EZOP | Carrying Value | Warehouse credit facility
Debt Instrument [Line Items]
Long-term debt	121,400	58,200
EZOP | Estimated Fair Value | Warehouse credit facility
Debt Instrument [Line Items]
Long-term debt	121,400	58,200
TEPIH | Carrying Value | Secured term loan
Debt Instrument [Line Items]
Long-term debt	0	110,595
TEPIH | Estimated Fair Value | Secured term loan
Debt Instrument [Line Items]
Long-term debt	0	110,595
HELII | Carrying Value | Solar asset-backed notes
Debt Instrument [Line Items]
Long-term debt	254,314	262,700
HELII | Estimated Fair Value | Solar asset-backed notes
Debt Instrument [Line Items]
Long-term debt	281,850	274,857
RAYSI | Carrying Value | Solar asset-backed notes
Debt Instrument [Line Items]
Long-term debt	133,155	0
RAYSI | Estimated Fair Value | Solar asset-backed notes
Debt Instrument [Line Items]
Long-term debt	139,004	0
HELIII | Carrying Value | Solar loan-backed notes
Debt Instrument [Line Items]
Long-term debt	154,573	0
HELIII | Estimated Fair Value | Solar loan-backed notes
Debt Instrument [Line Items]
Long-term debt	155,701	0
Revolving credit facility | TEPIIH | Carrying Value | Line of credit
Debt Instrument [Line Items]
Long-term debt	234,650	57,552
Revolving credit facility | TEPIIH | Estimated Fair Value | Line of credit
Debt Instrument [Line Items]
Long-term debt	234,650	57,552
Revolving credit facility | TEPH | Carrying Value | Line of credit
Debt Instrument [Line Items]
Long-term debt	90,325	0
Revolving credit facility | TEPH | Estimated Fair Value | Line of credit
Debt Instrument [Line Items]
Long-term debt	90,325	0
Revolving credit facility | TEPINV | Carrying Value | Line of credit
Debt Instrument [Line Items]
Long-term debt	95,207	0
Revolving credit facility | TEPINV | Estimated Fair Value | Line of credit
Debt Instrument [Line Items]
Long-term debt	$ 95,207	$ 0

Long-Term Debt - Schedule of _2

Long-Term Debt - Schedule of Long-term Debt Maturities (Details) $ in Thousands	Dec. 31, 2019USD ($)
Debt Disclosure [Abstract]
2020	$ 97,464
2021	154,285
2022	504,434
2023	74,649
2024	32,949
2025 and thereafter	634,930
Total	$ 1,498,711

Derivative Instruments - Narrat

Derivative Instruments - Narrative (Details) - Interest Rate Swap - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Aggregate notional amount of derivative	$ 524,103	$ 428,652
AP4
Derivative [Line Items]
Aggregate notional amount of unwound derivative		105,200
Aggregate notional amount of derivative		105,200
Cash received		666
AP6WII
Derivative [Line Items]
Aggregate notional amount of unwound derivative	84,100	101,400
Aggregate notional amount of derivative	103,500	63,600
Realized loss	8,700
Realized gain		5,700
LAPH
Derivative [Line Items]
Aggregate notional amount of unwound derivative		224,200
Aggregate notional amount of derivative		44,200
Realized gain		11,500
EZOP
Derivative [Line Items]
Aggregate notional amount of unwound derivative	264,600
Aggregate notional amount of derivative	255,800	102,600
Realized gain	81
TEPIH
Derivative [Line Items]
Aggregate notional amount of unwound derivative	102,900
Aggregate notional amount of derivative		41,700
Realized loss	3,500
TEPIIH
Derivative [Line Items]
Aggregate notional amount of derivative	171,200	$ 54,700
TEPH
Derivative [Line Items]
Aggregate notional amount of derivative	$ 103,100

Derivative Instruments - Outsta

Derivative Instruments - Outstanding Derivative Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Interest Rate Swap
Derivative [Line Items]
Aggregate Notional Amount	$ 524,103	$ 428,652
AP4 | Interest Rate Swap One
Derivative [Line Items]
Fixed Interest Rate	2.338%	2.338%
Aggregate Notional Amount	$ 99,762	$ 102,921
AP4 | Interest Rate Swap
Derivative [Line Items]
Aggregate Notional Amount		105,200
AP6WII | Interest Rate Swap Two
Derivative [Line Items]
Fixed Interest Rate	0.00%
Aggregate Notional Amount	$ 0	72,025
AP6WII | Interest Rate Swap
Derivative [Line Items]
Aggregate Notional Amount	$ 103,500	$ 63,600
AP6WII | Interest Rate Swap | Minimum
Derivative [Line Items]
Fixed Interest Rate		2.402%
AP6WII | Interest Rate Swap | Maximum
Derivative [Line Items]
Fixed Interest Rate		3.254%
LAPH | Interest Rate Swap Three
Derivative [Line Items]
Fixed Interest Rate	3.409%	3.409%
Aggregate Notional Amount	$ 43,298	$ 44,205
LAPH | Interest Rate Swap
Derivative [Line Items]
Aggregate Notional Amount		44,200
EZOP | Interest Rate Swap Four
Derivative [Line Items]
Aggregate Notional Amount	100,083	55,290
EZOP | Interest Rate Swap
Derivative [Line Items]
Aggregate Notional Amount	$ 255,800	$ 102,600
EZOP | Interest Rate Swap | Minimum
Derivative [Line Items]
Fixed Interest Rate	1.631%	1.90%
EZOP | Interest Rate Swap | Maximum
Derivative [Line Items]
Fixed Interest Rate	2.62%	3.014%
TEPIH | Interest Rate Swap Five
Derivative [Line Items]
Fixed Interest Rate	0.00%
Aggregate Notional Amount	$ 0	$ 99,536
TEPIH | Interest Rate Swap
Derivative [Line Items]
Aggregate Notional Amount		$ 41,700
TEPIH | Interest Rate Swap | Minimum
Derivative [Line Items]
Fixed Interest Rate		2.35%
TEPIH | Interest Rate Swap | Maximum
Derivative [Line Items]
Fixed Interest Rate		3.104%
TEPIIH | Interest Rate Swap Six
Derivative [Line Items]
Aggregate Notional Amount	225,845	$ 54,675
TEPIIH | Interest Rate Swap
Derivative [Line Items]
Aggregate Notional Amount	$ 171,200	$ 54,700
TEPIIH | Interest Rate Swap | Minimum
Derivative [Line Items]
Fixed Interest Rate	1.909%	2.995%
TEPIIH | Interest Rate Swap | Maximum
Derivative [Line Items]
Fixed Interest Rate	3.383%	3.383%
TEPH | Interest Rate Swap Seven
Derivative [Line Items]
Fixed Interest Rate		0.00%
Aggregate Notional Amount	$ 55,115	$ 0
TEPH | Interest Rate Swap
Derivative [Line Items]
Aggregate Notional Amount	$ 103,100
TEPH | Interest Rate Swap | Minimum
Derivative [Line Items]
Fixed Interest Rate	1.62%
TEPH | Interest Rate Swap | Maximum
Derivative [Line Items]
Fixed Interest Rate	1.928%

Derivative Instruments - Balanc

Derivative Instruments - Balance Sheet (Details) - Not designated as hedging instrument - Interest rate swap - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Total, net	$ (27,129)	$ (7,891)
Other assets
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	360	270
Other current liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, fair value	(397)	0
Other long-term liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, fair value	$ (27,092)	$ (8,161)

Derivative Instruments - Intere

Derivative Instruments - Interest Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized loss	$ 19,237	$ 6,100	$ 5,944
Interest Rate Swap and Swaptions | Interest Expense
Derivative Instruments, Gain (Loss) [Line Items]
Realized (gain) loss	13,195	(17,004)	3,295
Unrealized loss	19,237	6,100	5,944
Total	$ 32,432	$ (10,904)	$ 9,239

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Loss Carryforwards [Line Items]
Effective income tax rate	0.00%	0.00%	0.00%
Income tax	$ 0	$ 0	$ 0
Income tax expense for revaluation of net deferred tax asset			$ 6,100,000
Valuation allowance	284,976,000	$ 246,602,000
Tax credit carryforward	246,800,000
Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	806,600,000
Investment Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Tax credit carryforward	$ 20,500,000

Income Taxes - Effective Income

Income Taxes - Effective Income Tax Rate Reconciliation (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Loss before income tax	$ (133,434,000)	$ (68,409,000)	$ (90,182,000)
Statutory federal tax rate	21.00%	21.00%	35.00%
Tax benefit computed at statutory rate	$ (28,021,000)	$ (14,366,000)	$ (31,564,000)
State income tax, net of federal benefit	(8,344,000)	(4,308,000)	(3,406,000)
Enactment of the Tax Cuts and Jobs Act	0	0	6,118,000
Redeemable noncontrolling interests	(2,293,000)	(1,226,000)	0
ITC recapture	296,000	989,000	0
Other	852,000	234,000	1,185,000
Increase in valuation allowance, net	37,510,000	18,677,000	27,667,000
Total income tax	$ 0	$ 0	$ 0

Income Taxes - Deferred Tax Ass

Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Federal net operating loss carryforward	$ 169,379	$ 137,810
State net operating loss carryforward	49,565	38,659
ITC carryforward	246,828	226,378
Federal unused interest deduction carryforward	22,559	10,202
Investment in certain financing arrangements	36,999	16,374
Other deferred tax assets	20,801	11,531
Deferred tax assets	546,131	440,954
Fixed asset basis difference	(235,510)	(188,087)
Investment in certain financing arrangements	(22,826)	(5,391)
Other deferred tax liabilities	(2,819)	(874)
Deferred tax liabilities	(261,155)	(194,352)
Valuation allowance	(284,976)	(246,602)
Net deferred tax asset	$ 0	$ 0

Details of Certain Subsidiary_3

Details of Certain Subsidiary Assets and Liabilities (Details) - USD ($) $ in Thousands		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Balance Sheet Statements, Captions [Line Items]
Cash		$ 83,485	$ 52,706	$ 56,318
Accounts receivable—trade, net		10,672	6,312
Accounts receivable—other		6,147	3,721
Other current assets		174,016	26,794
Total current assets		274,320	89,533
Property and equipment, net		1,745,060	1,328,457
Customer notes receivable, net		297,975	172,031
Other assets		169,712	75,064
Total assets	[1]	2,487,067	1,665,085
Accounts payable		36,190	20,075
Accrued expenses		39,544	18,650
Current portion of long-term debt		97,464	26,965
Other current liabilities		21,804	13,214
Total current liabilities		195,002	95,404
Long-term debt, net		1,346,419	872,249
Other long-term liabilities		127,406	66,453
Total liabilities	[1]	1,668,827	$ 1,078,287
Reportable Legal Entities [Member] | Subsidiaries | Sunnova Energy Corporation Consolidated
Condensed Balance Sheet Statements, Captions [Line Items]
Cash		82,788
Accounts receivable—trade, net		10,672
Accounts receivable, net—affiliates		0
Accounts receivable—other		6,147
Other current assets		174,016
Total current assets		273,623
Property and equipment, net		1,745,060
Customer notes receivable, net		297,975
Other assets		169,712
Total assets		2,486,370
Accounts payable		36,190
Accounts payable, net—affiliates		0
Accrued expenses		39,544
Current portion of long-term debt		97,464
Other current liabilities		21,720
Total current liabilities		194,918
Long-term debt, net		1,308,812
Other long-term liabilities		127,406
Total liabilities		1,631,136
Reportable Legal Entities [Member] | Subsidiaries | LAPH Consolidated
Condensed Balance Sheet Statements, Captions [Line Items]
Cash		1,323
Accounts receivable—trade, net		497
Accounts receivable, net—affiliates		0
Accounts receivable—other		0
Other current assets		172
Total current assets		1,992
Property and equipment, net		54,558
Customer notes receivable, net		0
Other assets		1,815
Total assets		58,365
Accounts payable		14
Accounts payable, net—affiliates		1,220
Accrued expenses		87
Current portion of long-term debt		1,392
Other current liabilities		818
Total current liabilities		3,531
Long-term debt, net		40,727
Other long-term liabilities		7,606
Total liabilities		51,864
Reportable Legal Entities [Member] | Subsidiaries | EZOP
Condensed Balance Sheet Statements, Captions [Line Items]
Cash		2,143
Accounts receivable—trade, net		367
Accounts receivable, net—affiliates		78
Accounts receivable—other		0
Other current assets		5,314
Total current assets		7,902
Property and equipment, net		0
Customer notes receivable, net		125,950
Other assets		6,629
Total assets		140,481
Accounts payable		16
Accounts payable, net—affiliates		0
Accrued expenses		44
Current portion of long-term debt		0
Other current liabilities		165
Total current liabilities		225
Long-term debt, net		119,222
Other long-term liabilities		27,796
Total liabilities		147,243
Reportable Legal Entities [Member] | Subsidiaries | TEPH Consolidated
Condensed Balance Sheet Statements, Captions [Line Items]
Cash		14,672
Accounts receivable—trade, net		295
Accounts receivable, net—affiliates		0
Accounts receivable—other		4
Other current assets		47,388
Total current assets		62,359
Property and equipment, net		168,348
Customer notes receivable, net		0
Other assets		5,564
Total assets		236,271
Accounts payable		247
Accounts payable, net—affiliates		80,298
Accrued expenses		282
Current portion of long-term debt		0
Other current liabilities		697
Total current liabilities		81,524
Long-term debt, net		89,680
Other long-term liabilities		1,442
Total liabilities		$ 172,646
[1]	The consolidated assets as of December 31, 2019 and 2018 include $790,211 and $411,325 , respectively, of assets of variable interest entities ("VIEs") that can only be used to settle obligations of the VIEs. These assets include cash of $7,347 and $3,674 as of December 31, 2019 and 2018 , respectively; accounts receivable—trade, net of $1,460 and $884 as of December 31, 2019 and 2018 , respectively; accounts receivable—other of $4 and $109 as of December 31, 2019 and 2018 , respectively; other current assets of $47,606 and $4,821 as of December 31, 2019 and 2018 , respectively; property and equipment, net of $726,415 and $398,693 as of December 31, 2019 and 2018 , respectively; and other assets of $7,379 and $3,144 as of December 31, 2019 and 2018 , respectively. The consolidated liabilities as of December 31, 2019 and 2018 include $13,440 and $9,260 , respectively, of liabilities of VIEs whose creditors have no recourse to Sunnova Energy International Inc. These liabilities include accounts payable of $1,926 and $4,278 as of December 31, 2019 and 2018 , respectively; accrued expenses of $35 and $14 as of December 31, 2019 and 2018 , respectively; other current liabilities of $612 and $296 as of December 31, 2019 and 2018 , respectively; and other long-term liabilities of $10,867 and $4,672 as of December 31, 2019 and 2018 , respectively.

Related-Party Transactions - Re

Related-Party Transactions - Related Party (Details) - Executive Officer - USD ($) $ in Thousands	1 Months Ended		12 Months Ended
	Aug. 31, 2019	Jun. 30, 2019	Dec. 31, 2019	Jan. 31, 2019
Related Party Transaction [Line Items]
Notes receivable, related party, annual forgiveness percentage			25.00%
Promissory Notes
Related Party Transaction [Line Items]
Notes receivable, related party				$ 1,700
Notes receivable forgiven		$ 1,400
Bonus for tax liability reimbursement	$ 892,000

Redeemable Noncontrolling Int_2

Redeemable Noncontrolling Interests (Details) - USD ($)	1 Months Ended								12 Months Ended
	Dec. 31, 2019	Aug. 31, 2019	Jun. 30, 2019	Jan. 31, 2019	May 31, 2018	Dec. 31, 2017	Nov. 30, 2017	Mar. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Noncontrolling Interest [Line Items]
Non-performance fees paid									$ 1,300,000	$ 0	$ 0
Non-performance fees liability	$ 566,000								$ 566,000	$ 1,300,000
TEPI
Noncontrolling Interest [Line Items]
Capital commitment						$ 97,500,000	$ 91,100,000	$ 80,000,000
TEPII
Noncontrolling Interest [Line Items]
Capital commitment			$ 45,000,000			30,000,000
TEPIIB
Noncontrolling Interest [Line Items]
Capital commitment					$ 57,000,000	$ 40,000,000
TEPIII
Noncontrolling Interest [Line Items]
Capital commitment				$ 50,000,000
TEPIVA
Noncontrolling Interest [Line Items]
Capital commitment		$ 75,000,000
TEPIVB
Noncontrolling Interest [Line Items]
Capital commitment	$ 50,000,000
Minimum | Class A Members
Noncontrolling Interest [Line Items]
Allocation of income (loss)									93.00%
Minimum | Class B Members
Noncontrolling Interest [Line Items]
Allocation of income (loss)									1.00%
Minimum | Flip Date | Class A Members
Noncontrolling Interest [Line Items]
Allocation of income (loss)									1.00%
Minimum | Flip Date | Class B Members
Noncontrolling Interest [Line Items]
Allocation of income (loss)									93.00%
Maximum | Class A Members
Noncontrolling Interest [Line Items]
Allocation of income (loss)									99.00%
Maximum | Class B Members
Noncontrolling Interest [Line Items]
Allocation of income (loss)									7.00%
Maximum | Flip Date | Class A Members
Noncontrolling Interest [Line Items]
Allocation of income (loss)									7.00%
Maximum | Flip Date | Class B Members
Noncontrolling Interest [Line Items]
Allocation of income (loss)									99.00%

Stockholders' Equity (Details)

Stockholders' Equity (Details) - USD ($)	Aug. 19, 2019	Jul. 29, 2019	Jul. 24, 2019	Aug. 19, 2019	Jan. 31, 2018	Oct. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Mar. 31, 2018	Nov. 30, 2017	Nov. 01, 2017	Apr. 01, 2017	Mar. 31, 2017
Class of Stock [Line Items]
Non-cash issuance of convertible preferred stock relating to the reduction of debt							$ 0	$ 0	$ 15,190,000
Series A and Series C convertible preferred Stock
Class of Stock [Line Items]
Conversion terms, public offering aggregate gross proceeds, net							$ 175,000,000
Conversion of shares (in shares)							1
Conversion terms, offering price ratio							125.00%
Conversion terms, affirmative vote							80.00%
Series A convertible preferred stock
Class of Stock [Line Items]
Convertible preferred stock, authorized (in shares)										47,149,592			45,006,429	38,576,939
Issuance of stock, net (in shares)									4,033,061
Stock issuance price (in USD per share)									$ 5.3246735
Cash received for convertible preferred stock									$ 50,100,000
Non-cash issuance of convertible preferred stock relating to the reduction of debt						$ 15,200,000
Non-cash exchange of convertible preferred stock (in shares)						1,222,799
Stock converted (in shares)		46,351,877
Convertible preferred stock
Class of Stock [Line Items]
Convertible preferred stock, authorized (in shares)										64,294,899
Series C convertible preferred stock
Class of Stock [Line Items]
Convertible preferred stock, authorized (in shares)										17,145,306
Issuance of stock, net (in shares)								13,006,780
Stock issuance price (in USD per share)								$ 5.80
Cash received for convertible preferred stock								$ 176,000,000
Stock converted (in shares)		14,127,140
Series B convertible preferred stock
Class of Stock [Line Items]
Conversion terms, affirmative vote							75.00%
Convertible preferred stock, authorized (in shares)											4,714,959
Issuance of stock, net (in shares)					13,013				4,583,576
Stock issuance price (in USD per share)											$ 3.73
Mandatory preferred stock conversion, shares price threshold (in USD per share)							$ 6.6558
Cash received for preferred stock					$ 113,000				$ 39,900,000
Convertible preferred stock, exchanged (in shares)										4,763,086
Series B Common Stock
Class of Stock [Line Items]
Stock converted (in shares)		23,870
Common stock, authorized (in shares)								9,544,300
Series A Common Stock
Class of Stock [Line Items]
Shares issued in conversion of stock (in shares)		23,870
Common stock, authorized (in shares)						64,294,899				77,153,879		68,581,225
Share reserved issuance upon preferred stock conversion (in shares)										64,294,899
Common Stock
Class of Stock [Line Items]
Issuance of stock, net (in shares)							14,865,267
Non-cash exchange of convertible preferred stock (in shares)							69,115,618
Shares issued in conversion of stock (in shares)		60,479,017
Common Stock | Series B Common Stock
Class of Stock [Line Items]
Issuance of stock, net (in shares)							2,143	644	12,712
Non-cash exchange of convertible preferred stock (in shares)							(23,870)
Common Stock | Series A Common Stock
Class of Stock [Line Items]
Non-cash exchange of convertible preferred stock (in shares)							(8,612,731)
IPO
Class of Stock [Line Items]
Shares issued (in shares)			14,000,000
Common stock offering price (in USD per share)			$ 12
Underwriting discounts and commissions				$ 10,700,000
Offering expenses				5,400,000
Sale of stock, net proceeds				$ 162,300,000
Underwriters' option
Class of Stock [Line Items]
Shares issued (in shares)	865,267
Common stock offering price (in USD per share)	$ 12			$ 12
Pre-Reverse Stock Split | Series A convertible preferred stock
Class of Stock [Line Items]
Convertible preferred stock, authorized (in shares)										110,000,000			105,000,000	90,000,000
Issuance of stock, net (in shares)									9,409,174
Non-cash exchange of convertible preferred stock (in shares)						2,852,790
Stock converted (in shares)		108,138,971
Pre-Reverse Stock Split | Convertible preferred stock
Class of Stock [Line Items]
Convertible preferred stock, authorized (in shares)										150,000,000
Pre-Reverse Stock Split | Series C convertible preferred stock
Class of Stock [Line Items]
Convertible preferred stock, authorized (in shares)										40,000,000
Issuance of stock, net (in shares)								30,344,827
Stock converted (in shares)		32,958,645
Pre-Reverse Stock Split | Series B convertible preferred stock
Class of Stock [Line Items]
Convertible preferred stock, authorized (in shares)											11,000,000
Issuance of stock, net (in shares)					30,360				10,693,501
Convertible preferred stock, exchanged (in shares)										11,112,285
Pre-Reverse Stock Split | Series B Common Stock
Class of Stock [Line Items]
Common stock, authorized (in shares)								20,000,000
Pre-Reverse Stock Split | Series A Common Stock
Class of Stock [Line Items]
Common stock, authorized (in shares)						150,000,000				180,000,000		160,000,000
Share reserved issuance upon preferred stock conversion (in shares)										150,000,000

Equity-Based Compensation - Nar

Equity-Based Compensation - Narrative (Details)	Jul. 29, 2019USD ($)shares	Apr. 30, 2018shares	May 31, 2017USD ($)	Apr. 30, 2017shares	Dec. 31, 2019USD ($)shares	Dec. 31, 2019USD ($)planshares	Dec. 31, 2018USD ($)shares	Dec. 31, 2017USD ($)shares	Mar. 31, 2016shares	Jan. 31, 2015shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of stock option plans | plan						2
Share-based compensation expense | $			$ 653,000			$ 9,200,000	$ 3,000,000	$ 1,500,000
Stock options granted (in shares)						94,295	1,834,876
Stock options exercised (in shares)						2,143	1,393
Stock options vested (in shares)						1,765,410	577,594
Stock options vested | $						$ 6,000,000	$ 1,800,000
Total unrecognized compensation expense | $					$ 1,500,000	$ 1,500,000
LTIP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized (in shares)	5,229,318
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of non-vested awards becoming exercisable	50.00%
Awards becoming exercisable (in shares)	995,517
Accelerated vesting expense | $	$ 3,200,000
Stock options granted (in shares)		24,860		8,572		94,295	1,810,016	407,204
Stock options exercised (in shares)						2,143		11,571
Net exercised (in shares)							1,393	2,034
Issued (in shares)							644	1,141
Expected dividend yield						0.00%	0.00%	0.00%
Weighted average period						3 months 10 days
Stock Options | Prior Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized (in shares)										26,032
Stock Options | 2016 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized (in shares)									4,288,950
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted (in shares)						1,431,555
Unrecognized compensation expense | $					$ 14,300,000	$ 14,300,000
Weighted average period						2 years 6 months
Restricted Stock Units | LTIP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted (in shares)					1,431,555
Awards granted, fair value | $						$ 17,100,000
Share-based Payment Arrangement, Tranche One | Restricted Stock Units | LTIP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period						1 year
Share-based Payment Arrangement, Tranche Two | Restricted Stock Units | LTIP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period						3 years
Share-based Payment Arrangement, Tranche Three | Restricted Stock Units | LTIP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period						7 years
Pre-Reverse Stock Split | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted (in shares)		58,000		20,000			4,222,850	950,047
Stock options exercised (in shares)								27,000
Net exercised (in shares)							3,250	4,750
Issued (in shares)							1,505	2,663

Equity-Based Compensation - Sch

Equity-Based Compensation - Schedule of Stock Options Assumptions (Details) - Stock Options	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	0.00%	0.00%	0.00%
Risk-free interest rate	2.62%	2.62%	2.11%
Expected term	7 years 11 months 8 days	7 years 11 months 8 days	8 years 3 days
Volatility	81.00%	81.00%	68.00%

Equity-Based Compensation - Sto

Equity-Based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Number of Stock Options
Outstanding, beginning balance (in shares)	4,808,390	3,166,008
Granted (in shares)	94,295	1,834,876
Exercised (in shares)	(2,143)	(1,393)
Forfeited (in shares)	(596,233)	(191,101)
Outstanding, ending balance (in shares)	4,304,309	4,808,390	3,166,008
Number of options, exercisable (in shares)	3,339,913
Number of options, vested and expected to vest (in shares)	4,304,309
Number of options, non-vested (in shares)	964,396	3,124,367
Weighted Average Exercise Price
Outstanding, beginning balance (in USD per share)	$ 15.90	$ 15.65
Granted (in USD per share)	13.58	16.26
Exercised (in USD per share)	1.85	1.85
Forfeited (in USD per share)	15.85	15.23
Outstanding, ending balance (in USD per share)	15.86	$ 15.90	$ 15.65
Weighted average exercise price, exercisable (in USD per share)	15.86
Weighted average exercise price, vested and expected to vest (in USD per share)	$ 15.86
Weighted Average Remaining Contractual Term (Years)
Outstanding	7 years 29 days	8 years 1 month 2 days	8 years 4 months 9 days
Granted	9 years 25 days	9 years 3 months 10 days
Exercisable	6 years 10 months 20 days
Vested and expected to vest	7 years 29 days
Weighted Average Grant Date Fair Value
Granted (in USD per share)	$ 3.11	$ 3.52
Forfeited (in USD per share)	3.48	3.33
Non-vested (in USD per share)	$ 3.52	$ 3.48
Aggregate Intrinsic Value
Outstanding, beginning balance	$ 129	$ 124
Exercised	20	6
Outstanding, ending balance	242	$ 129	$ 124
Exercisable	242
Vested and expected to vest	$ 242

Equity-Based Compensation - Res

Equity-Based Compensation - Restricted Stock Activity (Details) - Restricted Stock Units - $ / shares	12 Months Ended
	Dec. 31, 2019
Number of Restricted Stock Units
Outstanding, beginning balance (in shares)	0
Granted (in shares)	1,431,555
Forfeited (in shares)	(5,416)
Outstanding, ending balance (in shares)	1,426,139
Weighted Average Grant Date Fair Value
Granted (in USD per share)	$ 11.93
Forfeited (in USD per share)	12
Outstanding (in USD per share)	$ 11.93

Basic and Diluted Net Loss Pe_3

Basic and Diluted Net Loss Per Share - Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net loss attributable to stockholders									$ (144,351)	$ (74,246)	$ (91,085)
Deemed dividends on convertible preferred stock exchange									0	(19,332)	0
Net loss attributable to common stockholders—basic	$ (17,509)	$ (37,590)	$ (63,260)	$ (50,717)	$ (53,017)	$ (17,865)	$ (23,269)	$ (41,721)	(169,076)	(135,872)	(121,288)
Net loss attributable to common stockholders—diluted	$ (17,509)	$ (37,590)	$ (63,260)	$ (50,717)	$ (53,017)	$ (17,865)	$ (23,269)	$ (41,721)	$ (169,076)	$ (135,872)	$ (121,288)
Net loss per share attributable to common stockholders—basic and diluted (in USD per share)	$ (0.21)	$ (0.62)	$ (7.32)	$ (5.87)	$ (6.14)	$ (2.07)	$ (2.69)	$ (4.83)	$ (4.14)	$ (15.74)	$ (14.05)
Weighted average common shares outstanding—basic and diluted (shares)									40,797,976	8,634,477	8,632,936
Series A Convertible Preferred Stock
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Dividends earned on convertible preferred stock									$ (19,271)	$ (36,346)	$ (29,623)
Series B convertible preferred stock
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Dividends earned on convertible preferred stock									0	0	(580)
Series C convertible preferred stock
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Dividends earned on convertible preferred stock									$ (5,454)	$ (5,948)	$ 0

Basic and Diluted Net Loss Pe_4

Basic and Diluted Net Loss Per Share - Anti-Dilutive Weighted Average Shares (Details) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Equity-based compensation awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	4,954,286	4,307,614	3,408,202
Convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	33,960,624	53,112,246	37,977,786
Convertible senior notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	104,320	0	0

Commitments and Contingencies

Commitments and Contingencies - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Loss Contingencies [Line Items]
Current portion of performance guarantee obligations	$ 4,067	$ 2,580
Letter of credit outstanding	725	725
Other commitment	32,800
Payments for dealer commitments	31,700
Subsidiary restricted net assets	548,100
Performance Guarantee Obligations
Loss Contingencies [Line Items]
Performance guarantee obligations	6,468	6,044	$ 4,173
Current portion of performance guarantee obligations	4,100	2,600
Long-term portion of performance guarantee obligations	$ 2,400	$ 3,500

Commitments and Contingencies_2

Commitments and Contingencies - Performance Guarantee Obligations (Details) - Performance Guarantee Obligations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Performance Guarantee Obligations [Roll Forward]
Balance at beginning of period	$ 6,044	$ 4,173
Accruals for obligations issued	3,101	3,033
Settlements made in cash	(2,677)	(1,162)
Balance at end of period	$ 6,468	$ 6,044

Commitments and Contingencies_3

Commitments and Contingencies - Lease Expenses and Other Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Operating lease expense	$ 1,248	$ 972	$ 972
Finance lease amortization expense	8	0	0
Short-term lease expense	48	50	21
Variable lease expense	1,037	704	661
Sublease income	(73)	(70)	(41)
Total	2,268	1,656	1,613
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	1,254	875	814
Operating cash flows from finance leases	8	0	0
Right-of-use assets obtained in exchange for lease obligations:
Operating leases	8,087	0	4,175
Finance leases	$ 13	$ 0	$ 0
Weighted average remaining lease term (years):
Operating leases	9 years 4 months 28 days	3 years 5 months 1 day
Finance leases	8 months 4 days
Weighted average discount rate:
Operating leases	3.94%	4.63%
Finance leases	4.26%

Commitments and Contingencies_4

Commitments and Contingencies - Lease Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Right-of-use assets:
Operating leases	$ 9,668	$ 2,586
Finance leases	5	0
Total right-of-use assets	9,673	2,586
Current lease liabilities:
Operating leases	556	871
Finance leases	5	0
Long-term leases liabilities
Operating leases	9,389	2,083
Total lease liabilities	$ 9,950	$ 2,954

Commitments and Contingencies_5

Commitments and Contingencies - Future Minimum Lease Payments (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Operating Leases
2020 / 2019	$ 1,037	$ 989
2021 / 2020	1,536	842
2022 / 2021	1,559	863
2023 / 2022	1,594	512
2024 / 2023	1,616	0
2025 / 2024 and thereafter	7,617	0
Total	14,959	3,206
Amount representing interest	(2,603)	(252)
Amount representing leasehold incentives	(2,411)
Present value of future payments	9,945	2,954
Current portion of lease liability	(556)	(871)
Long-term portion of lease liability	9,389	2,083
Finance Leases
2020	5
2021	0
2022	0
2023	0
2024	0
2025 and thereafter	0
Total	5
Amount representing interest	0
Amount representing leasehold incentives	0
Present value of future payments	5
Current portion of lease liability	(5)	$ 0
Long-term portion of lease liability	$ 0

Commitments and Contingencies -

Commitments and Contingencies - Dealer Commitments (Details)	Dec. 31, 2019USD ($)
Long-term Purchase Commitment [Line Items]
Total	$ 32,800,000
Long-Term Dealer Commitments
Long-term Purchase Commitment [Line Items]
2020	24,184,000
2021	24,200,000
2022	25,240,000
2023	1,000,000
2024	0
2025 and thereafter	0
Total	$ 74,624,000

Commitments and Contingencies_6

Commitments and Contingencies - Purchase Commitments (Details) $ in Thousands	Dec. 31, 2019USD ($)
Commitments and Contingencies Disclosure [Abstract]
2020	$ 22,702
2021	27,359
2022	27,243
2023	27,053
2024	20,152
2025 and thereafter	0
Total	$ 124,509

Commitments and Contingencies_7

Commitments and Contingencies - Future Commitments (Details) $ in Thousands	Dec. 31, 2019USD ($)
Commitments and Contingencies Disclosure [Abstract]
2020	$ 4,962
2021	3,269
2022	10
2023	0
2024	0
2025 and thereafter	0
Total	$ 8,241

Subsequent Events (Details)

Subsequent Events (Details) - Subsequent Event - USD ($) $ in Millions	1 Months Ended
	Feb. 29, 2020	Feb. 27, 2020
AP4
Subsequent Event [Line Items]
Repayments of debt	$ 92
TEPIIH
Subsequent Event [Line Items]
Repayments of debt	226.6
LAPH
Subsequent Event [Line Items]
Repayments of debt	$ 32
SOLI Series 2020-1 Class A | Solar asset-backed notes | SOLI
Subsequent Event [Line Items]
Principal amount of debt issued		$ 337.1
Discount percent	0.89%
Stated interest rate		3.35%
SOLI Series 2020-1 Class B | Solar asset-backed notes | SOLI
Subsequent Event [Line Items]
Principal amount of debt issued		$ 75.4
Discount percent	0.85%
Stated interest rate		5.54%

Selected Quarterly Financial _3

Selected Quarterly Financial Data (Unaudited) Statements of Operation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 33,614	$ 36,615	$ 34,612	$ 26,715	$ 25,206	$ 30,429	$ 28,963	$ 19,784	$ 131,556	$ 104,382	$ 76,856
Total operating expense, net	42,769	42,513	37,322	31,222	37,623	27,025	26,528	26,936	153,826	118,112	87,211
Operating loss	(9,155)	(5,898)	(2,710)	(4,507)	(12,417)	3,404	2,435	(7,152)	(22,270)	(13,730)	(10,355)
Net loss	(13,762)	(34,369)	(49,807)	(35,496)	(39,102)	(6,647)	(9,224)	(13,436)	(133,434)	(68,409)	(90,182)
Net loss attributable to common stockholders—basic	(17,509)	(37,590)	(63,260)	(50,717)	(53,017)	(17,865)	(23,269)	(41,721)	(169,076)	(135,872)	(121,288)
Net loss attributable to common stockholders—diluted	$ (17,509)	$ (37,590)	$ (63,260)	$ (50,717)	$ (53,017)	$ (17,865)	$ (23,269)	$ (41,721)	$ (169,076)	$ (135,872)	$ (121,288)
Net loss per share attributable to common stockholders—basic and diluted (in USD per share)	$ (0.21)	$ (0.62)	$ (7.32)	$ (5.87)	$ (6.14)	$ (2.07)	$ (2.69)	$ (4.83)	$ (4.14)	$ (15.74)	$ (14.05)

Schedule I Parent Company Fin_2

Schedule I Parent Company Financial Statements - Condensed Balance Sheets (Details) - USD ($) $ in Thousands		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash		$ 83,485	$ 52,706	$ 56,318
Total current assets		274,320	89,533
Total assets	[1]	2,487,067	1,665,085
Current liabilities:
Accrued expenses		39,544	18,650
Total current liabilities		195,002	95,404
Long-term debt, net		1,346,419	872,249
Total liabilities	[1]	1,668,827	1,078,287
Stockholders' equity:
Common stock		8	0
Additional paid-in capital—common stock		1,007,751	85,439
Accumulated deficit		(361,824)	(286,312)
Total stockholders' equity		645,935	501,118	$ 371,183	$ 325,466
Total liabilities, redeemable noncontrolling interests and stockholders' equity		2,487,067	1,665,085
Parent Company
Current assets:
Cash		696	0
Total current assets		696	0
Investments in subsidiaries		891,330	0
Total assets		892,026	0
Current liabilities:
Accrued expenses		83	0
Total current liabilities		83	0
Long-term debt, net		37,607	0
Total liabilities		37,690	0
Stockholders' equity:
Common stock		8	0
Additional paid-in capital—common stock		987,760	0
Accumulated deficit		(133,432)	0
Total stockholders' equity		854,336	0
Total liabilities, redeemable noncontrolling interests and stockholders' equity		$ 892,026	$ 0
[1]	The consolidated assets as of December 31, 2019 and 2018 include $790,211 and $411,325 , respectively, of assets of variable interest entities ("VIEs") that can only be used to settle obligations of the VIEs. These assets include cash of $7,347 and $3,674 as of December 31, 2019 and 2018 , respectively; accounts receivable—trade, net of $1,460 and $884 as of December 31, 2019 and 2018 , respectively; accounts receivable—other of $4 and $109 as of December 31, 2019 and 2018 , respectively; other current assets of $47,606 and $4,821 as of December 31, 2019 and 2018 , respectively; property and equipment, net of $726,415 and $398,693 as of December 31, 2019 and 2018 , respectively; and other assets of $7,379 and $3,144 as of December 31, 2019 and 2018 , respectively. The consolidated liabilities as of December 31, 2019 and 2018 include $13,440 and $9,260 , respectively, of liabilities of VIEs whose creditors have no recourse to Sunnova Energy International Inc. These liabilities include accounts payable of $1,926 and $4,278 as of December 31, 2019 and 2018 , respectively; accrued expenses of $35 and $14 as of December 31, 2019 and 2018 , respectively; other current liabilities of $612 and $296 as of December 31, 2019 and 2018 , respectively; and other long-term liabilities of $10,867 and $4,672 as of December 31, 2019 and 2018 , respectively.

Schedule I Parent Company Fin_3

Schedule I Parent Company Financial Statements - Condensed Balance Sheets (Parenthetical) (Details) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Condensed Financial Statements, Captions [Line Items]
Common stock, issued (in shares)	83,980,885	0
Common stock, par value (in USD per share)	$ 0.0001	$ 0.0001
Parent Company
Condensed Financial Statements, Captions [Line Items]
Common stock, issued (in shares)	83,980,885	0
Common stock, par value (in USD per share)	$ 0.0001	$ 0.0001
Series A convertible preferred stock
Condensed Financial Statements, Captions [Line Items]
Convertible preferred stock, issued (in shares)	0	44,942,594
Convertible preferred stock, par value (in USD per share)	$ 0.01	$ 0.01
Series C convertible preferred stock
Condensed Financial Statements, Captions [Line Items]
Convertible preferred stock, issued (in shares)	0	13,006,780
Convertible preferred stock, par value (in USD per share)	$ 0.01	$ 0.01
Series A Common Stock
Condensed Financial Statements, Captions [Line Items]
Common stock, issued (in shares)	0	8,612,728
Common stock, par value (in USD per share)	$ 0.01	$ 0.01
Series B Common Stock
Condensed Financial Statements, Captions [Line Items]
Common stock, issued (in shares)	0	21,727
Common stock, par value (in USD per share)	$ 0.01	$ 0.01

Schedule I Parent Company Fin_4

Schedule I Parent Company Financial Statements - Condensed Statements of Operations (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Financial Statements, Captions [Line Items]
Revenue	$ 33,614,000	$ 36,615,000	$ 34,612,000	$ 26,715,000	$ 25,206,000	$ 30,429,000	$ 28,963,000	$ 19,784,000	$ 131,556,000	$ 104,382,000	$ 76,856,000
General and administrative									97,986,000	67,430,000	54,863,000
Operating loss	(9,155,000)	(5,898,000)	(2,710,000)	(4,507,000)	(12,417,000)	3,404,000	2,435,000	(7,152,000)	(22,270,000)	(13,730,000)	(10,355,000)
Interest expense, net									108,024,000	51,582,000	59,847,000
Loss before income tax									(133,434,000)	(68,409,000)	(90,182,000)
Income tax									0	0	0
Net loss	$ (13,762,000)	$ (34,369,000)	$ (49,807,000)	$ (35,496,000)	$ (39,102,000)	$ (6,647,000)	$ (9,224,000)	$ (13,436,000)	(133,434,000)	(68,409,000)	(90,182,000)
Parent Company
Condensed Financial Statements, Captions [Line Items]
Revenue									0	0	0
General and administrative									418,000	0	0
Operating loss									(418,000)	0	0
Interest expense, net									83,000	0	0
Equity in losses of subsidiaries									132,933,000	0	0
Loss before income tax									(133,434,000)	0	0
Income tax									0	0	0
Net loss									$ (133,434,000)	$ 0	$ 0

Schedule I Parent Company Fin_5

Schedule I Parent Company Financial Statements - Condensed Statements of Cash Flow (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
CASH FLOWS FROM OPERATING ACTIVITIES
Net cash used in operating activities	$ (170,262)	$ (11,570)	$ (48,967)
CASH FLOWS FROM INVESTING ACTIVITIES
Net cash used in investing activities	(568,316)	(348,849)	(289,133)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from long-term debt	883,360	445,586	734,494
Payments of deferred financing costs	(12,110)	(8,598)	(27,627)
Proceeds from issuance of common stock, net	164,452	0	23
Proceeds from equity component of debt instrument, net	13,984	0	0
Other, net	(16)	(6)	(90)
Net cash provided by financing activities	801,823	365,687	369,893
Net increase in cash and restricted cash	63,245	5,268	31,793
Cash and restricted cash at beginning of period	87,046	81,778	49,985
Cash and restricted cash at end of period	150,291	87,046	81,778
Supplemental cash flow information:
Cash paid for interest	58,060	57,887	59,896
Cash paid for income taxes	0	0	0
Parent Company
CASH FLOWS FROM OPERATING ACTIVITIES
Net cash used in operating activities	0	0	0
CASH FLOWS FROM INVESTING ACTIVITIES
Investments in subsidiaries	(219,206)	0	0
Distributions from subsidiaries	2	0	0
Net cash used in investing activities	(219,204)	0	0
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from long-term debt	38,087	0	0
Payments of deferred financing costs	(377)	0	0
Proceeds from issuance of common stock, net	168,204	0	0
Proceeds from equity component of debt instrument, net	13,984	0	0
Other, net	2	0	0
Net cash provided by financing activities	219,900	0	0
Net increase in cash and restricted cash	696	0	0
Cash and restricted cash at beginning of period	0	0	0
Cash and restricted cash at end of period	696	0	0
Supplemental cash flow information:
Cash paid for interest	0	0	0
Cash paid for income taxes	$ 0	$ 0	$ 0

Schedule I Parent Company Fin_6

Schedule I Parent Company Financial Statements - Basis of Presentation (Details) - IPO	Jul. 24, 2019$ / sharesshares
Subsidiary, Sale of Stock [Line Items]
Shares issued (in shares) | shares	14,000,000
Common stock offering price (in USD per share) | $ / shares	$ 12
Parent Company
Subsidiary, Sale of Stock [Line Items]
Shares issued (in shares) | shares	14,000,000
Common stock offering price (in USD per share) | $ / shares	$ 12