I did consider it, and design the systems. I ran the numbers on heating and cooling and for a 2000/ft2 space using a heat pump I came out with an average 30 Kwh per day cooling/heating load. To do that in solar where I live with an average 4.3 Sun Hour Day it would take a 8.4 KW system. At a cost of $8 per watt new construction around $67,000 to install. Electric rates are falling here from 12.9 to 9.1 cents per Kwh. So a 8.7 KW system would generate about $2.73 per day. Figuring in inflation the ROI is around 50 years. Don't think I will ever live that long, not even my kids at age 25 would ever see it pay off.
Not to get off the topic, but how come when everyone uses their "formula" to figure out what the roi is, they always just give how much a kwh is? My electric bill doesn't just bill me for the kwh, i get transmission fees, distribution basic service, distribution on-peak, off-peak, combined public benefits charge, compeitive transmission assessment per kwh charge, non-bypassable fmcc per kwh on-peak, and offpeak... are ALL of these in the kwh for the formulas you guys use to compute how long the payoff is? My electric bill would be say 93.00 this past month, but no, all those fees add another 74$ for a total of 167$. Maybe I just don't understand how everyone comes up with the numbers they get, as far as I see it, i'd be reducing my bill in half by not having to pay ridiculous charges to everyone because they want a piece of the pie. Btw - is that 67,000$ solar system, after tax incentives?