Zero Energy Home Virginia:Solar PV-show me the money!

Everyone is always curious about the cost of solar PV and its "payback". So here's the numbers in black and white. The 4.2kW system cost $30,973 installed. The Commonwealth of Virginia gave us a rebate of $7189, and the Feds will give us a tax credit of $7135, resulting in a net cost of $16,649. We are selling the SRECs (Solar Renewable Energy Credits) for $200/yr. each (thanks to Cory, from olddominioninnovations.com, for brokering this) , for a total of approximately $800-1000 per year. The panels are generating from 11-25kWh per sunny day (less right now, with the shorter days & the sun lower in the sky; more come the long, high-in-the-sky days of early summer). So there it is, in black & white. I will leave it to each of you to decide how the "payback" looks to you, as the ways of calculating it are as myriad as the colors in the rainbow! All I know is that I love watching the digits in the Dominion Power digital meter get smaller!