Answers

While adding PV panels is a noble endeavor, it is unlikely to produce more than about one third of your annual electrical requirements.  Less than that, if you have air conditioning, even in a newly built, energy efficient home.  The financial savings, though, will continue to climb over time, as more dams and coal power are elliminated, and the cost of generation climbs steeply.  The payback time will shorten, and the lifecycle of the panels will net a return toward the rest of the power you use.