Property, plant and equipment (Tables)

12 Months Ended

Dec. 31, 2018

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