I know first-hand many businesses that recouped all of their investments into solar panels within 5 years of installation. The Federal credit, Oregon BETC, and some trust rebate......... between all of that, many had recouped at least 50-60% of costs within the first year of investment. My company recouped the cost within just over 3 years. Thank you, taxpayers. Of course, the OR and trust rebates the companies used have now expired, so I'm not totally on the up and up about what's available, at least state-wise.
I looked into it for our house. Unfortunately, I would have to cut down a few large trees before adding solar panels for maximum efficiency, so that just adds to my investment. Even with several gas appliances (furnace, cook range, clothes dryer, water heater, fireplace, etc) our electrical bill is $300-400/month, so anything I could do to decrease that would be fantastic. But for home energy, I just am not sold on the solar option.