Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Operating Activities
Net loss	$ (22,132)	$ (21,845)
Adjustments to reconcile net loss to net cash used in operating activities:
(Gain) from change in fair value of derivative warrant liability	(8)	(1)
Loss (gain) from change in fair value of 2020/21 Notes and 2020 Notes embedded derivative liability	29	(394)
Loss on conversion of 2020/21 Notes to common stock	543
Loss (gain) on retirement of property, plant and equipment	38	(19)
Stock-based compensation	1,347	938
Depreciation and amortization	4,754	4,849
Non-cash lease expense	45	25
Non-cash interest expense	606	1,089
Other non-cash expense		1
Changes in operating assets and liabilities:
Accounts receivable	765	148
Inventories	650	204
Prepaid expenses and other current assets, deposits and other assets	(613)	(23)
Accounts payable, accrued expenses and long-term liabilities	(605)	230
Net cash used in operating activities	(14,581)	(14,798)
Investing Activities
Acquisitions of property, plant and equipment	(1,756)	(5,779)
Proceeds from sale of property, plant and equipment		19
Investment in Juhl		(1,500)
Net cash used in investing activities	(1,756)	(7,260)
Financing Activities
Proceeds from SBA loans	1,006
Debt and equity offering costs	(6,170)	(178)
Proceeds from issuance of common stock and common stock warrants	69,985	9,647
Proceeds from exercise of warrants	16,647
Net settlement of common stock under stock plans	(331)	(201)
Payment of loans payable - other	(481)
Net cash provided by financing activities	80,656	9,268
Net increase (decrease) in cash and cash equivalents	64,319	(12,790)
us-gaap_CashAndCashEquivalentsAbstract
Beginning of period	16,302	33,734
End of period	80,621	20,944
Supplemental disclosures of cash and non-cash investing and financing transactions
Cash paid for interest	953	1,038
Non-cash purchase of property, plant and equipment	2	41
Issuance of common stock upon exchange of debt and make-whole	2,517
Issuance of common stock in exchange for services rendered	94
Original issue discount paid with 2020/21 Notes	282
Right-of-use asset purchased with financing lease	$ 13