Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Revenue:
Sales of fuel cell systems and related infrastructure	$ 9,121	$ 18,663	$ 14,339	$ 23,753
Services performed on fuel cell systems and related infrastructure	5,360	2,883	10,633	5,528
Power Purchase Agreements	3,062	1,077	5,768	2,054
Fuel delivered to customers	2,638	1,128	4,648	1,787
Other	278	258	403	303
Total revenue	20,459	24,009	35,791	33,425
Cost of revenue:
Sales of fuel cell systems and related infrastructure	8,043	14,753	11,941	19,832
Services performed on fuel cell systems and related infrastructure	5,926	5,368	11,709	10,138
Change in estimate	(1,071)		(1,071)
Power Purchase Agreements	3,616	933	6,497	1,684
Fuel delivered to customers	3,208	1,083	5,619	1,959
Other	353	310	542	361
Total cost of revenue	20,075	22,447	35,237	33,974
Gross profit (loss)	384	1,562	554	(549)
Operating expenses:
Research and development	5,201	3,425	10,031	6,326
Selling, general and administrative	8,559	8,002	16,849	15,751
Total operating expenses	13,760	11,427	26,880	22,077
Operating loss	(13,376)	(9,865)	(26,326)	(22,626)
Interest and other expense, net	(1,208)	(28)	(1,682)	(87)
Change in fair value of common stock warrant liability	1,456	667	2,734	2,436
Loss before income taxes	(13,128)	(9,226)	(25,274)	(20,277)
Income tax benefit			392
Net loss attributable to the Company	(13,128)	(9,226)	(24,882)	(20,277)
Preferred stock dividends declared	(26)	(27)	(52)	(53)
Net loss attributable to common shareholders	$ (13,154)	$ (9,253)	$ (24,934)	$ (20,330)
Net loss per share:
Basic and diluted (in dollars per share)	$ (0.07)	$ (0.05)	$ (0.14)	$ (0.12)
Weighted average number of common shares outstanding	180,282,904	173,439,391	180,204,334	173,402,611