Chapter 10 · Solar for ADUs and New Construction
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.