Part of designing good infrastructure is figuring out how many watts worth of solar can you permit given existing infrastructure; pretty much every grid connected solar installation has been permitted and approved. There will inevitably be a handful of illegal installs. But they're on a small enough scale that they aren't relevant.

If California has screwed that process up, their infrastructure is terribly designed. Most likely due to political reasons, by politicians wanting to meet solar install goals without wanting to spend the money to accommodate them.

If you are willing to spend that money, there is no technical reason why you couldn't put solar on every single roof in the nation. Oversupply conditions are a very solvable problem.