The Cool Roof Rating Council, located in Oakland, Calif., keeps a technical listing of the material properties of 1,000 products, which includes how reflective they are, and gives materials ratings up to 94%, says Jessica Clark, who works for the council.

The United States of America Department of Energy’s Energy Star rating for roofing products’ reflectivity calls for 65% efficiency new and 50% for used products. People are interested in white roofs because they reflect sunlight, which means less energy is needed for cooling.

This solar module manufacturer currently producing solar modules with the ability to absorb reflected light is Sanyo NA, whose headquarters is in San Diego, has produced a two-sided flat solar panel called the HIT Double. According to information sheets from the company, these panels from Sanyo will increase the solar power yield 30%.

The manufacturing of solar panels for both residential and commercial use is rapidly becoming a huge industry. There are a number of major solar panel manufacturers in the U.S. and a rapidly growing number in Europe. In recent years China has also become a major provider of solar panels both because they have high demand internally and because their low labor costs have helped to bring manufacturing costs down.

The Title 24 codes in California stipulate commercial roofs need to be white, led to an increase in the demand for white roofs in the state.