Every newly constructed detached ADU in Contra Costa County, California must include a Title 24-compliant solar PV system. Contra Costa County spans climate zones 3, 4, 12, which determines exactly how many kilowatts your specific project must install for code compliance.
Local building departments across Contra Costa County enforce Title 24 at plan check. Plans submitted without a properly sized solar system are routinely rejected unless a documented exemption (shading, roof area, structural) applies.
Contra Costa County spans from the bay to inland valleys with varied microclimates. Inland areas like Concord, Walnut Creek, and Antioch enjoy excellent solar production for ADU installations.
Title 24 multiplies your ADU's conditioned floor area by a climate-zone-specific kW factor. Across Contra Costa County's climate zones 3, 4, 12, most ADUs land in the 1.6–4.0 kW range — typically 4 to 10 modern (~400W) panels.
Title 24-compliant ADU solar packages range from $4,000 (Standard cash) to $15,000+ (Premium with battery) across Contra Costa County. HDM financing typically reduces effective cost by ~40% via commercial ITC pass-through. Main utilities serving the county: PG&E, MCE.
Yes. Title 24 is California state law and every jurisdiction in Contra Costa County enforces it at permit submittal.
Contra Costa County sits in climate zones 3, 4, 12. Use our cost calculator to map your exact ZIP code to its Title 24 climate zone.
Exemptions are project-specific, not countywide. The most common are shading (<70% annual solar access), insufficient roof area, and structural infeasibility. Your designer documents these on the CF1R compliance form.