Washington Revised Code Title 36. Counties § 36.70.025. “Solar energy system” defined

(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.