BALANCE SHEET COMPONENTS

9 Months Ended

Sep. 30, 2020

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets consisted of the following at September 30, 2020 and December 31, 2019, respectively:


	As of
	September 30, 2020		December 31, 2019

Materials and supplies	$	—	$	1,872
Prepaid expenses and current assets	3,800		2,551
Total prepaid expenses and other current assets	$	3,800	$	4,423

During the three and nine months ended September 30, 2020, the Company expensed $1.9 million of materials and supplies previously reflected in other current assets to research and development.

Property and Equipment

Property and equipment consist of the following at September 30, 2020 and December 31, 2019, respectively:


	As of
	September 30, 2020		December 31, 2019
Machinery and equipment	$	14,467	$	13,483
Furniture and fixtures	1,480		1,228
Leasehold improvements	1,447		1,437
Software	2,871		1,909
Building	33,248		33,248
Construction-in-progress	13,693		4,264
Other	1,815		1,309
Property and equipment, gross	69,021		56,878
Less: accumulated depreciation and amortization	(7,708)		(3,500)
Total property and equipment, net	$	61,313	$	53,378

Depreciation expense for the three months ended September 30, 2020 and 2019 was $1.5 million and $0.6 million, respectively. Depreciation expense for the nine months ended September 30, 2020 and 2019 was $4.2 million and $1.1 million, respectively.

Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following at September 30, 2020 and December 31, 2019, respectively:


	As of
	September 30, 2020		December 31, 2019
Accrued payroll and payroll related expenses	$	1,679	$	1,385
Accrued stock issuance and transaction costs	285		4,695
Accrued outsourced engineering services	8,979		3,205
Accrued legal expenses	5,978		243
Other accrued liabilities	4,931		1,237
Current portion of lease financing liability	727		660
Total accrued expenses and other current liabilities	$	22,579	$	11,425