A $50,000 system earns a $17,500 rebate (But not for much longer I think) and if SREC's are issued, and trading for a good price, a 12 year ROI is possible.
No SRECs here, the rebate is over and all we get is a standard tax credit. Same credit we would get for upgrading a furnace or putting insulation in, except the cap is higher. The amount of tax credit is 30 percent. So, if you spent 50 grand, you would get a 15 grand credit. Now, I don't know how it works if you paid less than 15 grand in taxes as a cash payment in excess of taxes paid would be rebate of sorts.
Where I live, that 50 grand system, regardless of how much is returned in credits or rebates, will still only produce less than 1000 dollars per year. More like 600.
We are pretty conservative. It's not uncommon to see electric bills of less than 500 kWh per month. My last bill was for 376 kWh, my highest last year was 697. Before taxes, by bill was 49 dollars. With bills that low, it's hard to justify a 30 to 50 thousand dollar solar system. Now, in CA, the land of excess, is much different. I know a guy that lives in LA and used 3,600 kWh from the POCO last month, plus has a decent solar array. His bills are over 500 per month. Solar panels are everywhere in LA. The price for energy is not that high, 17.5 cents per KWh.