@Q: that seems like a lot of square footage. My system is only 1.8 KW (50% of average usage), and it's done with eight 2x4 foot panels. If I've done the math right, sizing that up to 6 KW would require only 210 sq. ft.

I paid more for it than that, but I had it professionally installed (I'm pretty inept at that sort of thing), and tax breaks reduced the overall cost by about a third. I figure about a 9-year period for amortization, based on what I used to pay for electricity year around and the amount the power company pays me when the meter runs backward. I actually pay for power (maybe $15/month) three months out of the year, and that's when the days are shorter and the lights are on longer.