A house with 10-year-old solar panels on top is surely going to be worth more than a house with no solar panels on top, even if the cost of new panels comes dow

A house with 10-year-old solar panels on top is surely going to be worth more than a house with no solar panels on top, even if the cost of new panels comes down significantly over that time. As you point out, the panels continue generating returns for a long time after that. Moreover, people should not buy a house with the expectation that it will inevitably be worth more in 20 years than it is today. Appreciation of land values is far from a universal law of nature.