If you spend $25K on a solar installation, does the value of your home increase by $25K?

This angle isn't mentioned in the article. Overall the profitability of the installation seems shaky and depends on various government interventions that probably won't be around forever.

If we model the solar installation as a conversion of cash into home equity however, the calculus changes. You are buying home equity and getting reduced energy bills in the process. You almost certainly come out ahead, the panels are in a sense free, other than costing you some liquidity.

Googling around a Zillow study says solar installations increase the value of a home by 4% on average.

The article also didn't touch on maintenance costs.