There are three different Energy Star tax credit tiers, which specific products fall under.  Click here to visit the Energy Star Tax Credit Page and learn more about qualifying products and requirements.
Tier 1
Tax Credit: 10% of cost up to $500 or a specific amount from $50 – $300

Expires: December 31, 2011

Details: Must be an existing home & your principal residence. New construction and rentals do not qualify.
Products: Biomass Stoves, Heating Ventilating and Air Conditioning, Insulation, Roofs (Metal and Asphalt), Water Heaters (Non-solar), Windows and Doors
Tier 2

Tax Credit: 30% of cost with no upper limit

Expires: December 31, 2016

Details:Existing homes & new construction qualify. Both principal residences and second homes qualify. Rentals do not qualify.

Products: Geothermal Heat Pumps, Small Wind Turbines (Residential), Solar Energy Systems

Tier 3

Tax Credit: Credit Details: 30% of the cost, up to $500 per .5 kW of power capacity

Details: Existing homes & new construction qualify. Must be your principal residence. Rentals and second homes do not qualify.

Products: Fuel Cells (Residential Fuel Cell and Microturbine System)