It's still a terrible investment in the US if you are looking at it purely from a monetary perspective.

When I was looking at it, break even is usually just shy of 10 years, so let's call it that for easy math. You install a $20k solar system, and you end up making about $30k over a 25 year life span, assuming you never have any major issues and never move out of your house.

In contrast, you could dump that 20k into the stock market. With an average return of about 7-8% (the historical rate of the s&p500) you'd walk away with about $110-140k.

There's noble environmental reasons to do it, but financially it's just not a great return right now.

Edited to clarify: You'd also need to be paying for electric in the second example, so minus 50k over these 25 years. You're still up about double to triple over the solar panels.