Homeowners who bought energy efficient improvements can obtain tax credits for the purchases if the products fall under certain energy criteria.
Ten percent credit is given for improvements that meet or exceed the International Energy Conservation Code (and supplements) and are installed in the taxpayer's principal residence within the United States.
Eligible under the recent law are:

• Insulation that reduce heat loss/gain, up to $500
• Exterior windows and skylights, up to $500
• Exterior doors, up to $500
• Some metal roofs, up to $500

Moreover, credits are given for costs incurred on energy properties installed in homes.
The properties should, however, meet certification requirements of the Treasury Department.
The credits include:

• $50 for every advanced main circulating air fan
• $150 per natural gas, propane or oil furnace or hot water boiler
• $300 per other energy efficient property item like air conditioning system

The maximum allowable tax credit for both years is $500, but not more than $200 may be credited to expenditures for windows.
Tax credit is also granted for solar panels, solar water heaters, or fuel cell power plants installed in taxpayers' principal residences.
An eligible fuel cell plant makes electricity out of a fuel by electrochemical process, has electricity-only generation efficiency of above 30%, and produces electricity of at least 0.
5 kilowatts.
One credit equivalent to 30% of the cost of the solar panel is allowed, up to $2,000.
Credit for a solar water heating system is also allowed, but the system cannot be used to heat a pool or bathtub.
The power plant is eligible for 30% tax credit up to $500 per 0.
5 kilowatt electrical production capacity.
The creditable properties must have been installed and in use in 2006 and 2007.