California is set to become the first US state to make solar panels mandatory on most newly built homes.
The state’s Energy Commission is due to vote next week on new energy standards that would require virtually all new homes to be constructed with solar panels from 2020.
Bare minimum, all new buildings in the US should use good solar-aware design. It’s cheap to orient windows towards the south for passive solar heating, for example. All roofs should be able to have solar panels easily added later too. Too many new houses are built simply facing the wrong direction. (That’s not the type of thing you can really fix later.)