10.1 What's required for ADUs and new homes

10.1.1 California requires solar on new homes

The CEC's 2022 Single-Family Solar PV page states that the solar PV requirement applies to all newly constructed single-family residential buildings, including townhouses and R-3 single-family residential buildings.

10.1.2 New detached ADUs generally also require solar

The CEC ADU FAQ states that a newly built detached ADU can satisfy the 2022 Energy Code solar PV requirement by adding PV modules to the same residential lot. The added PV modules must be part of the ADU permit application and sized per the Energy Code.

Important: the new PV modules can attach to the existing main-house solar system. They are not required to live on the ADU's roof and are not required to feed the ADU meter — as long as the modules sit on the same residential lot and comply with Energy Code + utility / load-serving entity rules. In other words: even if the ADU has a separate electric meter, the PV doesn't have to connect to that meter.

10.1.3 Attached ADUs, garage conversions, and JADUs generally do not require solar

10.1.4 Minimum capacity for ADU / new home solar

The minimum capacity is calculated for you — you don't need to compute it yourself; it will already be in the building plan.

Important: if the calculated minimum requirement is under 1.8 kW, the project may be exempt and no installation is required.