Also, when you lease, yes - the leasing company gets the federal & utility rebates because they own the system. BUT they should be passing that on to you as a reduction in your lease rate. In our case, LADWP dropped their rebate rate between the time we first talked with them and when we signed, and SolarCity still gave us pricing based on the higher rebate amount.
We could have done the whole system with $0 down, but decided to just pay the full lease up front to get it over with because they give you a better lease price that way. Plus this way, if we decide to sell the house it's a dual selling point - no power costs AND the lease was paid up front. And let's be real.... if someone does $0 down, with the absurd price that property gets in SoCal, if someone can afford to buy a house and can qualify for a loan, I'd be SHOCKED if they didn't qualify to assume your solar lease. You don't exactly need amazing credit with these companies, and you're not talking a big amount of money.
I also am a fan of leasing because the way technology is going, something tells me in 20 years "you" will be better off getting a whole new system - currently even the best panels aren't all that efficient. Plus what I didn't mention about the inverter is that when leased, if it goes out, they replace it. Sungevity was giving 1 inverter during the lease period - openly saying we'd be responsible for buying AT LEAST one more during the lease for several thousand dollars. SolarCity will replace however many you need replaced. Plus if you buy from Mom & Pop Solar, if they go out of biz you are kind of screwed. At least with a national company you have a better chance of them lasting a while.
So to break it down, ours was $5700 up-front to pay off the lease minus the $1800 we'd be spending anyway to upgrade to 200amp = $3900 / 240mos = avg $16.25/month for all of our current level of power, which we are currently paying well more than that to LADWP.
Incidentally, the closest system to this that we found to buy was $18,000.