@nprofile1q... Where does he get the 22-27K range? That's ridiculously over spec for most residential systems. Your high quote of 13K is far more realistic for a grid-tied setup and about what I would assume the average household.

I had a 4.4 kW system installed for less than 15K nearly six years ago and it's paid for itself. The same money would get at least 1.5x the power now.