This is pretty key. If your roof is covered in shade most of the day throughout the year, it might not have a favorable enough “solar window” to justify the costs of panels.

That’s something you’ll want to assess before you move forward. If your roof won’t cut it, or you can’t make the call because you rent your apartment or live in a multi-unit building, you don’t have to give up on solar power altogether. Instead of installing your own panels, look into shared or community solar. This approach lets many different customers buy a stake in a solar installation and receive credits on their electricity bills.

If you do have a suitably sunlit rooftop to work with, Weissman says, make sure it’s in good shape structurally. Solar installations these days can come with warranties for 20 or 25 years. If your roof will need a renovation a few years down the road, it’ll be easier to take care of that before the array goes up. That way, you won’t have to pay in extra time and money to disconnect your panels during the roof renovation and put them up again afterwards. While you’re at it, make sure you won’t run afoul of any homeowners’ association covenants that ban rooftop solar for aesthetic reasons.

Lastly, envision the future of your yard. If the roof is unobstructed now but you’ve just planted a battalion of leafy oaks around your property, you might run in to trouble a few years down the road. Be prepared to prune your foliage to keep the panels clear.