10 Million-Solar Roofs Act of 2008 - Requires the Secretary of Energy to establish a program to provide rebates (for each watt of installed capacity) to eligible individuals or entities for the purchase and installation of photovoltaic systems, over a 10-year period, of at least an additional 10 million solar systems in the United States with a cumulative capacity of at least 30,000 megawatts.
Provides eligibility requirements for homeowners, businesses, nonprofit entities, and state and local governments. Sets minimum Energy Star or equivalent ratings that must be achieved by the buildings for which the photovoltaic system is installed.
Limits the total amount of a rebate to 50 percent of the purchase and installation cost of the system.