I've done these calculations, particularly after putting an 11.6Kw solar array on our last house, which was in St. Petersburg, FL, one of the sunniest places in

I've done these calculations, particularly after putting an 11.6Kw solar array on our last house, which was in St. Petersburg, FL, one of the sunniest places in the US. We sold the house after having the system for ~6.5 years, but we were tracking for a 9 year ROI. My cost was ~$23K out of pocket at the time, with power bills of $500-$800/mo., depending on time of year. I think our average daily consumption was 69Kwh, and the system produced the majority of that most days. Assuming an average power bill of $600/mo., $23K would cover roughly 3 years of power bills. However, if the money was invested in a decent-ish portfolio, it would be earning some interest along the way, which could stretch what it covers to 5+ years. Anyway, when I did all the math, the solar panels never really made money, but what they did was smooth out our monthly expenses and gave some hedge against rate increases. The new house is the same general area, and our use is about the same, but going to wait to see if solar takes a bigger decrease in cost before doing another array. It's mostly maintenance-free, but I did not output decline when the panels got dirty, and one panel died about 1 year after installation (and by then the installer company had gone out of business).