Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Operating Activities
Net loss	$ (28,660,000)	$ (27,976,000)
Adjustments to reconcile net loss to net cash used in operating activities:
(Gain) loss from the change in fair value of derivative warrant liability	(14,000)	2,976,000
(Gain) from the change in fair value of the embedded derivative to the 2020 Notes	(394,000)	(2,637,000)
Loss on sale of property, plant and equipment	4,000
Loss on exchange or conversion of debt		2,202,000
Stock-based compensation	1,349,000	683,000
Depreciation and amortization	6,656,000	6,520,000
Non-cash lease expense	48,000
Non-cash interest expense	1,346,000	1,706,000
Other non-cash expenses		6,000
Changes in operating assets and liabilities:
Accounts receivable	(609,000)	528,000
Inventories	(35,000)	1,196,000
Prepaid expenses and other current assets, deposits and other assets	(1,824,000)	(630,000)
Accounts payable, accrued expenses and long-term liabilities	1,294,000	(425,000)
Net cash used in operating activities	(20,839,000)	(15,851,000)
Investing Activities
Acquisitions of property, plant and equipment	(5,989,000)	(2,233,000)
Proceeds from sale of property, plant and equipment	32,000
Investment in Juhl	(1,500,000)
Net cash used in investing activities	(7,457,000)	(2,233,000)
Financing Activities
Payments on secured debt	(292,000)
Debt and equity offering costs	(232,000)	(392,000)
Proceeds from issuance of common stock and common stock warrants	11,589,000	39,394,000
Proceeds from the exercise of warrants		1,263,766
Net settlement of common stock under stock plans	(201,000)
Net cash provided by financing activities	10,864,000	40,265,000
Net (decrease) increase in cash and cash equivalents	(17,432,000)	22,181,000
Cash and cash equivalents, beginning of year	33,734,000	11,553,000
Cash and cash equivalents, end of year	16,302,000	33,734,000
Cash paid for interest	1,391,000	1,945,000
Non-cash purchase of property, plant and equipment	368,000	919,000
Equipment and insurance financed with notes payable	1,041,000
Conversion and exchanges of convertible debt for common stock		3,701,000
Fair value of 2020 Notes embedded derivative upon exchange		2,193,000
Fair value of warrants at issuance and upon exercise, net		$ 4,905,000