Many people downsize, or end up having to vote with their feet to a warm place that likes them. With subsidies, solar is still often a 20 year stay-put bet to break even. Most of us here are lucky to have 20 years left, having the same 4 walls to stare at or not.
So far with the past year's worth of performance, the only downside is opportunity cost. If I had used that HELOC money to invest in the market it would have made more than the "return" I'm getting on the solar project.