July 11, 2008

U.S. Scientists Develop Novel Windows to Channel Solar Energy

U.S. scientists develop novel windows to channel solar energy

WASHINGTON, July 10 (Xinhua) -- Imagine windows that not only provide a clear view and illuminate rooms, but also use sunlight to efficiently help power the building, according to a report by Engineers at Massachusetts Institute of Technology (MIT).

The work, appearing in the July 11 issue of the journal Science, involves the creation of a novel "solar concentrator.""Light is collected over a large area (like a window) and gathered, or concentrated, at the edges," explains Marc Baldo, leader of the work.

Rather than covering a roof with expensive solar cells, the new approach needs only cells to be equipped around the edges of a flat glass panel, Baldo says.

Because the system is simple to manufacture, the team believes that it can be implemented within three years -- even added onto existing solar-panel systems to increase their efficiency by 50 percent for minimal additional cost. That, in turn, will substantially reduce the cost of solar electricity.

Solar concentrators in use today "track the sun to generate high optical intensities, often by using large mobile mirrors that are expensive to deploy and maintain," Baldo and colleagues write in Science. Further, "solar cells at the focal point of the mirrors must be cooled, and the entire assembly wastes space around the perimeter to avoid shadowing neighboring concentrators."

The MIT solar concentrator involves a mixture of two or more dyes that is essentially painted onto a pane of glass or plastic. The dyes work together to absorb light across a range of wavelengths, which is then re-emitted at a different wavelength and transported across the pane to waiting solar cells at the edges.

The project utilizes innovative design to achieve superior solar conversion without optical tracking, says Aravinda Kini of the U.S. Department of Energy's Office of Science, a sponsor of the work.

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