In California, installers are required to have both a standard contractors license or possibly a C-46 Solar Contractors License. This license handles installations for photovoltaic systems, solar water and space heating, and solar pool heating. Other certifications you must watch out for, none of that happen to be legally necessary https://solarcompanieslivermore.wordpress.com/2025/07/20/why-homeowners-across-california-choose-american-array-solar-installers/