For investors, particularly after the ’08 financial crisis, it’s difficult to decide on where to put your money. Savings accounts have tiny profit margins, and the volatility of the stock market has left many skeptical. A recent study has found that if you want to invest, solar is the best bet—at least in 46 US states. For 21 million homeowners in the US the cost of solar power is cheaper than grid power, and if you can get an array on your roof with low-financing and around 5 percent interest over 25 years, you could be saving up to $100 a month. Stretch that out over a 25 year period and you’re looking at returns better than a stock portfolio filled with S&P 500 companies. A major factor in the study is the assumption that government incentives for solar will continue over the 25 year period, which is no guarantee.