We got ours about a year ago from SolarCity.

We got it with a 10 year 2.99% loan (so we got the tax credit). Even with loan payments we're already net positive since SDG&E is insane.

We probably could have gotten more value if we had waited a bit for prices to go down, but then you run the risk of the government changing the tax credit and also the risk of your utility tacking on additional fees that existing solar customers would get grandfathered out of.

So in 9 years they'll be paid off AND we'll have saved money already. Then there's another 10 years on the warranty, so that's all savings from then on.