It's not always a no-brainer. If you live in a good established neighborhood in a warmer climate you'd have to remove tree coverage. Even if you did that, it's the other guys not oil or gas that will make it a hassle.
Houses where the roof is completely in the shade from trees? That's not a very common sight.
New panels are much less impacted by shade. Friends out of town just installed the same setup as ours, didn’t want to cut down three monster Doug firs shading their roof in summer.
Made 6.9Mwh in 2025, only just less than ours with no shade at all.