Look hard at how that credit is structured, because it's often financed, and it often sits as a lien behind your mortgage. In many of these programs, the amount (you mentioned around $13,000; confirm the specifics of the program) is financing layered on top of your mortgage, frequently through a state program recorded as a second or third lien against the property. Those liens generally won't subordinate for a future refinance until the home has appreciated enough first, which can leave you stuck. On the upside-down question: stack a financed system on top of a minimum-down FHA purchase with upfront mortgage insurance and you're carrying very little equity early on. If values go flat for a stretch, you could be effectively upside-down for a while. That risk is real and worth pricing in. Run the actual payback math with a solar-savings calculator before assuming the system pays for itself. Solar has generally gotten more expensive over time, and system pricing varies enormously. We've seen a home with an $8,000 system sit next to comparable homes quoted $35,000 to $40,000 for similar output. Get the program's real terms and the lien position in writing, and pressure-test the payback math before you build it into your purchase.