Unaudited Quarterly Supplemental Financial Information (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue:	$ 213,606	$ 190,190	$ 168,881	$ 169,361	$ 123,251	$ 93,765	$ 86,783	$ 72,197	$ 742,038	$ 375,996	$ 208,540
Cost of revenue:	196,358	166,805	136,110	125,695	111,201	108,855	92,589	81,395	624,968	394,040	312,029
Gross profit (loss)	17,248	23,385	32,771	43,666	12,050	(15,090)	(5,806)	(9,198)	117,070	(18,044)	(103,489)
Research and development	32,970	27,021	14,413	14,731	15,181	12,374	12,368	11,223	89,135	51,146	46,848
Sales and marketing	24,983	21,476	8,254	8,262	9,346	6,561	8,663	7,845	62,975	32,415	29,101
General and administrative	47,471	40,999	15,359	14,988	14,818	13,652	14,325	12,879	118,817	55,674	61,545
Total operating expenses	105,424	89,496	38,026	37,981	39,345	32,587	35,356	31,947	270,927	139,235	137,494
Loss from operations	(88,176)	(66,111)	(5,255)	5,685	(27,295)	(47,677)	(41,162)	(41,145)	(153,857)	(157,279)	(240,983)
Interest income	1,996	1,467	444	415	0	0	0	0	4,322	759	394
Interest expense	(16,178)	(17,191)	(12,688)	(11,390)	(27,846)	(26,946)	(16,140)	(16,847)	(76,935)	(96,358)	(73,559)
Interest expense to related parties	(1,628)	(1,628)	(13,923)	(12,062)	(1,961)	(1,953)	(9,414)	(7,516)	(8,893)	(12,265)	(7,631)
Other expense, net	635	762	559	(629)	175	(40)	14	119	(999)	(491)	(773)
Loss on revaluation of warrant liabilities and embedded derivatives	(13)	1,655	(19,197)	(4,034)	(15,114)	572	(668)	215	(21,590)	(14,995)	(13,035)
Net loss before income taxes	(103,364)	(82,513)	(50,060)	(22,015)	(72,041)	(76,044)	(67,370)	(65,174)	(257,952)	(280,629)	(335,587)
Income tax provision	1,079	(3)	128	333	(120)	314	228	214	1,537	636	729
Net loss	(104,443)	(82,510)	(50,188)	(22,348)	(71,921)	(76,358)	(67,598)	(65,388)	(259,489)	(281,265)	(336,316)
Net loss attributable to noncontrolling interests and redeemable noncontrolling interests	(4,662)	(3,931)	(4,512)	(4,632)	(4,160)	(4,527)	(4,123)	(5,856)	(17,736)	(18,666)	(56,658)
Net loss attributable to Class A and Class B common stockholders	$ (99,781)	$ (78,579)	$ (45,677)	$ (17,716)	$ (67,761)	$ (71,831)	$ (63,475)	$ (59,532)	$ (241,753)	$ (262,599)	$ (279,658)
Net loss per share attributable to Class A and Class B common stockholders, basic and diluted (in dollars per share)	$ (0.91)	$ (0.97)	$ (4.34)	$ (1.70)	$ (6.56)	$ (6.97)	$ (6.22)	$ (5.87)	$ (4.54)	$ (25.62)	$ (27.84)
Weighted average shares used to compute net loss per share attributable to Class A and Class B common stockholders, basic and diluted (in shares)	109,416	81,321	10,536	10,403	10,333	10,305	10,209	10,143	53,268	10,248	10,046
Product
Revenue:	$ 156,671	$ 125,690	$ 108,654	$ 121,307	$ 66,913	$ 45,255	$ 39,935	$ 27,665	$ 512,322	$ 179,768	$ 76,478
Cost of revenue:	128,076	95,357	70,802	80,355	70,450	53,923	47,545	38,855	374,590	210,773	103,283
Installation
Revenue:	21,363	29,690	26,245	14,118	21,601	14,978	14,354	12,293	91,416	63,226	16,584
Cost of revenue:	31,819	40,118	37,099	10,438	16,933	14,696	14,855	13,445	119,474	59,929	17,725
Service
Revenue:	21,752	20,751	19,975	19,907	19,927	19,511	18,875	18,591	82,385	76,904	67,622
Cost of revenue:	28,475	22,651	19,260	24,253	14,012	30,058	21,308	18,219	94,639	83,597	155,034
Electricity
Revenue:	13,820	14,059	14,007	14,029	14,810	14,021	13,619	13,648	55,915	56,098	47,856
Cost of revenue:	$ 7,988	$ 8,679	$ 8,949	$ 10,649	$ 9,806	$ 10,178	$ 8,881	$ 10,876	$ 36,265	$ 39,741	$ 35,987