Cal. Pub. Res. Code § 25981

(a) As used in this chapter, “solar collector” means a fixed device, structure, or part of a device or structure, on the roof of a building, that is used primarily to transform solar energy into thermal, chemical, or electrical energy. The solar collector shall be used as part of a system that makes use of solar energy for any or all of the following purposes:
1. (1) Water heating.
2. (2) Space heating or cooling.
3. (3) Power generation.
(b) Notwithstanding subdivision (a), for the purpose of this chapter, “solar collector” includes a fixed device, structure, or part of a device or structure that is used primarily to transform solar energy into thermal, chemical, or electrical energy and that is installed on the ground because a solar collector cannot be installed on the roof of the building receiving the energy due to inappropriate roofing material, slope of the roof, structural shading, or orientation of the building.
(c) For the purposes of this chapter, “solar collector” does not include a solar collector that is designed and intended to offset more than the building’s electricity demand.
(d) For purposes of this chapter, the location of a solar collector is required to comply with the local building and setback regulations, and to be set back not less than five feet from the property line, and not less than 10 feet above the ground. A solar collector may be less than 10 feet in height only if, in addition to the five-foot setback, the solar collector is set back three times the amount lowered.