RCW 35.63.015: "Solar energy system" defined.

As used in this chapter, "solar energy system" means any device or combination of devices or elements which rely upon direct sunlight as an energy source, including but not limited to any substance or device which collects sunlight for use in: (1) The heating or cooling of a structure or building; (2) The heating or pumping of water; (3) Industrial, commercial, or agricultural processes; or (4) The generation of electricity. A solar energy system may be used for purposes in addition to the collection of solar energy. These uses include, but are not limited to, serving as a structural member or part of a roof of a building or structure and serving as a window or wall.