I have been lurking on this board for years, I usually don’t have anything to add, but this time I do.
Last year my wife and I brought a brand new house in Temecula, it came with solar. So far our highest monthly electric bill was 99 cents. The home builder said it was a $25,000 value, and we did get a pretty good tax rebate because of it this year.
If you were going to install a system on an existing house, I would think you would need to stay in the house for at least 10 years to recoup the investment. Figuring $200 a month electric bill.