Installing solar power at their Shelter Island, N.Y., Ace Hardware store seemed like the right thing to do for the planet, say owners David Gurney and Meredith Page. But now that the brother-and-sister ownership team have the system, they're finding that it's also good for their wallets.

Solar power was once just a luxury for well-funded corporate citizens like Wal-Mart and Google. But with the price of solar components plummeting, and rebates and other financing sweetening the pot, more small businesses are considering whether to run on the oldest form of energy. That's especially the case for those that have hefty power needs and operate in states where power is pricey. "Solar was once for a tree-hugger-type mentality," says Scott Maskin, president of solar installer SUNation Solar Systems in Oakdale, N.Y. "It's evolved to a financial decision."