The tax credit is even more generous for solar panels and geothermal HVAC systems, or newer technologies like wind energy and fuel cells. You'll get a 30 percent credit, with no upper limit and including installation, through 2016. "If you live out West, you might consider solar," says Jennifer Schwab, director of sustainability for Sierra Club Green Home; local rebates, lease-to-own deals, and monthly payment plans are making the investment more affordable. Geothermal systems cost $15,000 to $20,000 to install, but they have low operating costs, so you can recoup your investment in as little as four years if you're switching from electric heating and cooling (or about 12 years for natural gas). ClimateMaster is one brand to look for.
For newer technologies, the situation's a bit different. The payback for wind energy is highly variable—ranging from six to 30 years, Schwab says—and most turbines need a half-acre of land and wind speeds averaging 10 miles an hour or higher to create electricity. (EarthTronics recently introduced one that works at speeds as low as 2 mph, but few have been installed to date.) And not many options exist for the homeowner who wants to install fuel cells to make electricity. But stay tuned on how these technologies evolve—the credit is good for several more years.