California will require solar panels on all new housing, except tall apartment buildings.

There are various exceptions for cases where they would be ineffective, and the solar panels don't have to be physically on the building.

On tall apartment buildings, it would not be feasible for solar panels on the roof to provide enough electricity for all the residents, even on a sunny day. But that doesn't mean they would be wasted. They would be as efficient and useful there as anywhere else. So why not require them?