Note 5. Solar Energy Systems, net

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

	June 30, 2016			December 31, 2015
Solar energy system equipment costs	$	2,148,251		$	1,846,103
Inverters		217,931			177,202
Initial direct costs		93,185			68,280
Total solar energy systems		2,459,367			2,091,585
Less: accumulated depreciation and amortization		(254,470	)		(212,671	)
Add: construction-in-progress		77,832			113,107
Total solar energy systems, net	$	2,282,729		$	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 $22.5 million and $16.5 million for the three months ended June 30, 2016 and 2015, respectively, and $42.9 million and $32.0 million for the six months ended June 30, 2016 and 2015, respectively. The depreciation expense was reduced by the amortization of deferred grants of $3.4 million and $3.5 million for the three months ended June 30, 2016 and 2015, respectively, and $7.4 million and $7.1 million for the six months ended June 30, 2016 and 2015, respectively.