Note 6. Solar Energy Systems, net

Solar energy systems, net consists of the following (in thousands):

	December 31,
	2016			2015
Solar energy system equipment costs	$	2,459,856		$	1,846,103
Inverters		260,011			177,202
Initial direct costs		117,587			68,280
Total solar energy systems		2,837,454			2,091,585
Less: Accumulated depreciation and amortization		(303,305	)		(212,671	)
Add: Construction-in-progress		95,217			113,107
Total solar energy systems, net	$	2,629,366		$	1,992,021

All solar energy systems, construction-in-progress and inverters have been leased to or are subject to signed Customer Agreements with customers. The Company recorded depreciation expense related to solar energy systems of $93.4 million, $70.7 million and $54.7 million for the years ended December 31, 2016, 2015 and 2014, respectively. The depreciation expense was reduced by the amortization of deferred grants of $13.1 million, $14.2 million and $13.9 million for the years ended December 31, 2016, 2015 and 2014, respectively.