I just recently looked into this too. I think the federal government will give something like 20% back in the form of tax credits, from the cost of the solar panels. I don't think there is a limit to income or the cost, but obviously you need to pay taxes to get any benefit from the credit. The other typical source is from your utility company. In many states, the power company is required to get so much % of their power from "green" sources, whatever that means. If they don't do get enough, they'll be fined. So they have to purchase essentially carbon credits that are created (this is purely on paper), when someone installs a solar panel or other green system. So the power company will set a standard amount to buy those credits, based on how much the fine is, and how many people they think will install solar panels in a given period of time. But if they bought enough, they might not give you anything. In some states I think you can directly sell those credits in an auction, but I'm not clear how that works. Bottom line is that it's not very transparent, and the solar company can't promise you'll get compensated for sure since there are other factors out of their control.