The economics are changing though. An idealized stock market return is (used to be) 11.8%/year. This interest, compounded, doubles your position every 7 years

The economics are changing though. An idealized stock market return is (used to be) 11.8%/year. This interest, compounded, doubles your position every 7 years. Once solar has a break even period of less than 7 years, the investment in solar beats a rosy, idealized stock market. When the payoff period drops to 4 years, you'd be an idiot _not_to do solar, because you're looking at an investment returning numbers in the credit card interest rate range. I bought my current system for $45k four years ago. I only did it because the investment math worked in my case. (Yes, yes yes. It was for sure subsidized and the investment math _didn't_ work without the subsidies.) Now, however, that same system would cost me ~$20k. I checked when my coworker was looking into solar and wanted to run the numbers. The economics of solar are approaching beat-the-[idealized]-stock market investment. 4 years is a rule-of-thumb number for many businesses for investing in capital. That is, if a capital investment breaks even in 4 years, you pull the trigger. Once the economics hits 4 years for break even, you'll see a lot of CFO's start pulling the trigger, not to mention the encouragement from the marketing department for the optics. Anyways, I think it is coming and for many of us, it is already here.