An ROI of 12 years on a house is pretty good, especially when you think your loan is probably 30 years. I've taken a lot of solar continuing ed credits and designed one system myself. Current ROI's are closer to 8 years and I was told by a PhD EE that in four more years that should be cut in half. I'm skeptical of a 4 year ROI, but if true, you'd be borderline stupid not to. I'm already tempted. Energy prices will not go down. Demand is continually increasing and the less government reliance in my life, the better.
Solar systems have a lot of options too. Might just augment your daytime electric usage. Other options include battery storage (which is the most expensive part), generator backups, servo's on the panels to optimize sun intake, and reselling back to the grid.
