trades82:  "I was actually wrong. Just got the proposal last week. It's 13.3 kW. "

OK, if you are meaning 13,300 kWh per year, as I think you mean, then for a home in the 2,000 to 2,500 square foot range that should be enough to power it for a year, presuming your package includes adequate ESU and that you have no abnormal power useage situations.  Congratulations!  You are going in for it big time.  

With past PV cells and the panels that are constructed using older PV technology the degredation rate was much higher, but the new PV cells and panels degrade their output at a much slower rate so you should have a high percentage output for many years in the future, not to mention that the newer cells have a higher output in the first place.  I think you and your family will be very happy with the solar set up package you have.  As I mentioned previously I am half way through my 5th year with no problems, no maintenance issues and very little degradation of output.     Okiedo