You can get a maximum of $1,500 from the federal tax credit over the two-year period of 2009 to 2010 for energy efficiency improvements made on your principal residence. You can take part of the $1,500 in 2009, and the rest in 2010 if you made purchases in separate years. If you get the entire $1,500 credit in 2009, then you cannot receive a credit in 2010. This tax credit is non-refundable; therefore, you cannot get more back in tax credits than you pay in federal income tax. New construction does not qualify for this tax credit and you cannot carry it forward to future years.

The $1,500 maximum does not apply to geothermal heat pumps, solar water heaters, solar panels, and wind generators added to your principal or secondary residence. All these measures are eligible for a 30 percent tax credit with no upper limit until December 31, 2016. The tax credit for fuel cells continues until 2016 but is limited to $500 per 0.5 kilowatts of power capacity and improvements must be on your primary residence. Like the credit above, both these tax credits are non-refundable. If you are unable to claim the entire 30 percent of your renewable energy purchase, you can carry forward the unclaimed portion to future years.