Annual report pursuant to Section 13 and 15(d)

Property, plant and equipment

Property, plant and equipment

12 Months Ended

Dec. 31, 2018

Property, Plant and Equipment [Abstract]

Property, plant and equipment at December 31, 2018 and 2017 consisted of the following:



	Estimated Useful Life (in Years)	2018			2017
Energy systems	1 - 15 years	$	12,709,990		$	12,466,642
Machinery and equipment	5 - 7 years	1,355,617			1,215,951
Furniture and fixtures	5 years	222,542			205,320
Computer software	3 - 5 years	200,626			115,253
Leasehold improvements	*	450,792			440,519
		14,939,567			14,443,685
Less - accumulated depreciation and amortization		(3,666,452		)	(2,177,974		)
Net property, plant and equipment		$	11,273,115		$	12,265,711

* Lesser of estimated useful life of asset or lease term

Depreciation and amortization expense on property and equipment for the years ended December 31, 2018 and 2017 was $1,537,622 and $1,114,540, respectively.

In December 2018, the Company sold certain energy systems related assets and related energy production contracts. As the sales agreement contained a repurchase provision, no sale was recognized. Accordingly, the assets were not derecognized and the $2.0 million consideration for the sale was deferred. Subsequent to December 31, 2018, the sales agreement was modified to exclude the repurchase provision (see Note 18. "Subsequent Events").

Subsequent to December 31, 2018, the Company contracted for the disposition of certain energy systems (see Note 18. "Subsequent events").