We installed a 6.36 Kw ground mount system in 2013. About $32,000. We had state and federal tax credits and a utility rebate that covered 2/3s of that cost. Since ours is on a great solar site, it paid for itself in 7 years. We are on a common net metering program where our solar generation is netted against our monthly usage. State regulation of solar varies considerably and will continue to do so. In many states solar generation is credited to the monthly bill based on the retail price of electricity, not the market price of electricity. That is a big win for those that have solar. Some states have modified their net metering programs to credit back solar generation based on the market price of electricity, which is normally (current Texas and 2000 California excluded) considerably less than the retail price.
