Converting a garage into an ADU in Sonoma County, California? Most garage conversions are exempt from Title 24's solar mandate because they're treated as remodels of existing structures rather than new construction. Here's exactly how it works countywide.
Title 24's PV mandate applies to "newly constructed" low-rise residential buildings. A garage conversion is permitted as an alteration of an existing structure, so it falls outside the new-construction trigger across all Sonoma County jurisdictions.
Two situations trigger the mandate: (1) tearing the garage down and rebuilding it as an ADU, and (2) significantly expanding the footprint. Local plan-checkers in Sonoma County will flag this on submittal.
Even when not required, many Sonoma County homeowners add solar to garage-conversion ADUs to offset tenant electricity load and qualify for the 30% federal Investment Tax Credit. ROI is typically strong given PG&E/SCP retail rates.
Your designer files a CF1R form documenting the project as an alteration. The plan-checker confirms exemption and your permit moves forward without a solar requirement.
Yes. Voluntary solar is treated as a normal residential interconnect with PG&E (or your utility) and qualifies for the federal ITC.