I deployed solar panels when I replaced my roof in 2004; the total out of pocket cost after state rebates and federal and state taxes was $14,612. The system generates about 15 KwH on a good day; I live in a tract home in Mountain View, CA. So far, the panels have generated 19,225 KwH, which reduced my energy bill by $10,392 as of May, 2009. I've not seen the expected degradation in the power production, but it's difficult to measure due to changes in the weather -- it's entirely possible that 2004-2005 were cloudier than 2007-2008, or something like that. In any event, the system has delivered between 3819 and 3930 KwH every year. I'm extraordinarily happy with the way this has worked out.