My light bill, in the summer, in one of the hottest, most humid parts of the United States is between $120 and $150 a month. How long would it take, for my solar system with it's $20,000+ price tag, my maintanance bills and insurance bill, to pay for itself? I'm 41, will it happen before I die? Let's see some numbers on that since you know more than the rest of us working stiffs.And why would you want to spend your money on such a system? Because it reduces your electrical bill.