Asset Retirement Obligations ("ARO")

3 Months Ended

Mar. 31, 2022

Asset Retirement Obligation Disclosure [Abstract]

AROs consist primarily of costs to remove solar energy system assets and costs to restore the solar energy system sites to the original condition, which we estimate based on current market rates. For each solar energy system, we recognize the fair value of the ARO as a liability and capitalize that cost as part of the cost basis of the related solar energy system. The related assets are depreciated on a straight-line basis over 30 years, which is the estimated average time a solar energy system will be installed in a location before being removed, and the related liabilities are accreted to the full value over the same period of time. We revise our estimated future liabilities based on recent actual experiences, including third party cost estimates, average size of solar energy systems and inflation rates, which we evaluate at least annually. Changes in our estimated future liabilities are recorded as either a reduction or addition in the carrying amount of the remaining unamortized asset and the ARO and either decrease or increase our depreciation and accretion expense amounts prospectively. The following table presents the changes in AROs as recorded in other long-term liabilities in the unaudited condensed consolidated balance sheets:


	As of March 31,
	2022		2021
	(in thousands)
Balance at beginning of period	$	54,396	$	41,788
Additional obligations incurred	2,573		2,290
Accretion expense	840		652

Other	(30)		(16)
Balance at end of period	$	57,779	$	44,714