A utility may elect to invest in RECs to meet any portion of, or the entirety of, each annual renewable resource target in RCW 19.285.040(2) or 19.285.050(1). If the cost of the RECs and the incremental cost of acquired renewable resources, as documented according to WAC 194-37-150 through 194-37-190, for any one year meets or exceeds four percent of the utility's annual revenue requirement, the utility shall document that the utility achieved the four percent cost cap alternative compliance path in RCW 19.285.050(1). The documentation must include copies of its WREGIS RECs, copies of purchase contracts, and its annual revenue requirement.