California Title 24 ADU Solar Requirements DC Rating Calculator

Find your climate zone here.

DC Rating (kWPV):

The DC rating is calculated using the formula:

DC Rating = (CFA * CFAa) / 1000 + (NDU * NDUa)

where CFAa and NDUa are constants based on the climate zone.

If your DC rating exceeds 1.8, you might be required to install a PV system

See Fact Sheet: Single-family and Low-rise Multifamily Solar and Battery Systems 2022 for more info