Grid scale installations are also amortized over many people (?!?!). This is literally why governments and corporations exist.

And rooftop solar had to be subsidized in the US, so apparently it wasn't attractive enough as an investment on its own. Even now, solar without batteries isn't economically beneficial to individuals, and batteries are ludicrously expensive and require a lot of space.

> I'm surprised to hear that you need to replace roofs every fifteen years.

Asphalt shingles. Of course you can use something else like a metal roof. But the solar panel itself doesn't last that long since efficiency drops and new technology gets so much better. So you're still gonna have a new part of your house that can break whenever it feels like it and needs maintenance every so often. Something I want the government or a utility company to deal with, please.