John Grabowski wrote:

The solar fallacy sort of follows the same thinking as purchasing
your own home is a good investment. Of course your home will
appreciate in value over time. However when you add up the interest
paid on the mortgage, the taxes, insurance, maintenance and upkeep as
well as the purchasing and selling costs it can actually be a loss.

You have completely discounted the value of "feeling good about saving the
environment." While admittedly this is hard to quantify, contentment is
often a high-priced item.

For those for whom intent trumps results, solar panels would be a good deal
at twice the price.