White Roof Coatings Boost Solar

March 1, 2013

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Companies making white roof coatings and emulsions are seeing an increased call for photovoltaic solar power systems which are capable of absorbing the albedo, which is reflected light coming off of a flat or low angle roof. White sheet materials reflect up to about 80%, but companies manufacturing liquid products offer 90% and even greater reflectivity; attuned solar systems offer 20 to 30% greater power outputs than more commonly-used flat panels, according to industry insiders.

The majority of the white sheet roofing materials are controlled by the following manufacturers: Firestone, Carlisle, Johns Manville, and GAF. White sheets are made using materials such as vinyl, and EPDM, not to mention the fastest growing thermoplastic polyoelfin (TPO).

An article in Wikipedia describes TPO as being comprised of “polymer/filler blends typically made from a small portion of polypropylene, polyethylene, block copolymer polypropylene, rubber, and filler for reinforcement.” According to one industry estimate, over one third of all roofing installations include the use of TPO.

Liquid products are more likely to be used when adding new coats to black or white roofs due to the lower cost of liquid as compared to sheets, according to Jonathan Ursini, a representative from DuROCK Alfacing International, of Woodbridge, Ontario, Canada. DuRock manufactures Tio-Coat, a product made from titanium dioxide and 40 additional components, like Rhoplex EC-3100 from Dow, a polymer completely comprised of acrylic which is used in pigmented elastomeric basecoats. There is 89% reflectivity efficiency offered by using tri-coat. He claimed that it took them five years to formulate the product and they wanted to improve the performance some more. He pointed out that the life of sheet material can be increased by up to ten years with the coating. Tio-coat is able to cover asphalt, concrete, foam, or metal.

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.

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