California Code, Public Utilities Code - PUC § 2854.6

(a) On or before July 1, 2019, the commission shall develop standardized inputs and assumptions to be used in the calculation and presentation of electric utility bill savings to a consumer that can be expected by using a solar energy system by vendors, installers, or financing entities, and the commission and each electrical corporation shall post these standardized inputs and assumptions on their Internet Web sites.

(b) For purposes of this section, “solar energy system” means a solar energy device to be installed on a residential building that has the primary purpose of providing for the collection and distribution of solar energy for the generation of electricity, that produces at least one kW, and not more than five MW, alternating current rated peak electricity, and that meets or exceeds the eligibility criteria established pursuant to Section 25782 of the Public Resources Code.