Even more than that once solar panel companies all realize they should increase prices since homeowners are obligated to buy from one of them.
I’m not sure why you are being downvoted. your prediction is hardly guaranteed but not entirely absurd either. it’s nice to have a guaranteed market
See Pharma companies for an example of what happens when you have a guaranteed market that capitalises on research funded by the public. Solar is very similar.
I thought the expensive thing in California was land, not the houses that sit on them?
There is plenty of land. The main bottleneck is regulatory approval. But high construction cost are also a dampening factor.