The Company's finite-lived intangible assets and liabilities represent revenue contracts, consisting of long-term concessions and licensing contracts, power purchase agreements (“PPAs”), RECs, lease agreements and operations and maintenance (“O&M”) contracts that were obtained through third party acquisitions. The revenue contract intangibles are comprised of favorable and unfavorable rate PPAs and REC agreements and the in-place value of market rate PPAs. The lease agreement intangibles are comprised of favorable and unfavorable rate land leases, and the O&M contract intangibles consist of unfavorable rate O&M contracts. Intangible assets and liabilities that have determinable estimated lives are amortized on a straight-line basis over those estimated lives. Amortization of favorable and unfavorable rate revenue contracts is recorded within operating revenues, net in the consolidated statements of operations. Amortization expense related to the concessions and licensing contracts and in-place value of market rate revenue contracts is recorded within depreciation, accretion and amortization expense in the consolidated statements of operations, and amortization of favorable and unfavorable rate land leases and unfavorable rate O&M contracts is recorded within cost of operations. The straight-line method of amortization is used because it best reflects the pattern in which the economic benefits of the intangibles are consumed or otherwise used up. The amounts and useful lives assigned to intangible assets acquired and liabilities assumed impact the amount and timing of future amortization.
Impairment of Renewable Energy Facilities and Intangibles
Long-lived assets that are held and used are reviewed for impairment whenever events or changes in circumstances indicate carrying values may not be recoverable. An impairment loss is recognized if the total future estimated undiscounted cash flows expected from an asset are less than its carrying value. An impairment charge is measured as the difference between an asset's carrying amount and its fair value. Fair values are determined by a variety of valuation methods, including appraisals, sales prices of similar assets and present value techniques.
During the year ended December 31, 2018, the Company recognized a $15.2 million non-cash impairment charge within its Solar segment related to an operating project within its Enfinity portfolio due to the bankruptcy of a significant customer. During the years ended December 31, 2016 and 2017, the Company recognized an impairment charge of $15.7 million and $1.4 million, respectively, within impairment of renewable energy facilities in the consolidated statements of operations, on its 11.4 MW portfolio of residential rooftop solar assets that was classified as held for sale as of December 31, 2016, and subsequently sold in 2017. The Company also recorded a $3.3 million charge within impairment of renewable energy facilities for the year ended December 31, 2016 due to the decision to abandon certain residential construction in progress assets that were not completed by SunEdison as a result of the SunEdison Bankruptcy. Impairment charges are reflected within impairment of renewable energy facilities in the consolidated statements of operations (see Note 4. Acquisitions and Dispositions and Note 5. Renewable Energy Facilities for further discussion).
The Company evaluates goodwill for impairment at least annually on December 1st. The Company performs an impairment test between scheduled annual tests if facts and circumstances indicate that it is more-likely-than-not that the fair value of a reporting unit that has goodwill is less than its carrying value. A reporting unit is either the operating segment level or one level below, which is referred to as a component. The level at which the impairment test is performed requires judgment as to whether the operations below the operating segment constitute a self-sustaining business or whether the operations are similar such that they should be aggregated for purposes of the impairment test. The Company defines its reporting units to be consistent with its operating segments.
The Company may first make a qualitative assessment of whether it is more-likely-than-not that a reporting unit’s fair value is less than its carrying value to determine whether it is necessary to perform the quantitative goodwill impairment test. The qualitative impairment test includes considering various factors including macroeconomic conditions, industry and market conditions, cost factors, a sustained share price or market capitalization decrease and any reporting unit specific events. If it is determined through the qualitative assessment that a reporting unit’s fair value is more-likely-than-not greater than its carrying value, the quantitative impairment test is not required. If the qualitative assessment indicates it is more-likely-than-not that a reporting unit’s fair value is not greater than its carrying value, the Company must perform the quantitative impairment test. The Company may also elect to proceed directly to the quantitative impairment test without considering such qualitative factors.