Friday, July 11, 2008

MIT Solar Concentrator Improves Solar Cell Efficiency and Design Options


MIT Solar Concentrator Concept Photo
Imagine if every window in a skyscraper was a solar concentrator.

MIT Solar Concentrator Innovation: More Bang for your Buck
Solar concentrators do what you might expect, concentrate solar light. Usually they are large mirrors or other devices, but the goal of any solar concentrator is to concentrate the light that falls on a large area to a smaller one. The idea is that the (usually cheap) solar concentrator increases the efficiency of the (usually expensive) solar cell, getting more energy for input of money. Recent advances in this technology have focused around better performance of the solar cell, like the IBM's solar cell cooling technology, but not this time.

The MIT solar concentrator, devised by a group led by Marc Baldo at the Massachusetts Institute of Technology, takes advantage of recent advances in laser technology and materials science to develop a 'window' that concentrates solar light that would normally pass through a window, and pushes (some) of the light to edge of the glass. The concentrator passes the first test in that it is cheap to produce, and it may even be effective at increasing efficiencies of existing solar cells.

How The MIT Solar Concentrator Works
When light passes through the window it hits a dye that has been placed inside the window itself. This dye absorbs the photon, and re-emits a photon at a lower wavelength. The catch here is that the dye has emitted a light photon within the window itself. The material of the window is designed in such a way that light emitted within the window is directed to the outer edge of the glass. A detailed analysis of the inner working can be found on the MIT solar concentrator new release

Solar Design Innovation
Solar technology has seen incredible innovation, such as the advances in dye sensitized solar cells, it is not surprising that solar concentrators will continue to improve and become more varied. The real innovation here is that with today's technology the scientists believe this can be made cheap, and may be a product you can purchase within 3 years.

With this new form factor, colored windows might be the latest design trend, and framing a window might become a bit more complex. "Where do I put the solar cells? Can I shim that?" However, as mentioned above, this technology can also theoretically be applied to existing solar cells where it is estimated to improve solar efficiencies by up to 50%.

Solar Concentrator Challenges For the Future
The biggest problem with the new technology may be longevity. The existing designs last for about 3 months in testing, not the 5-15 years most people want out of their solar cells (not to mention windows). The scientists hope that borrowing the technology that protects OLED's from moisture and air could be used to extend the life of this new device. However, OLED's themselves have been plagued by this very same design challenge for years.

The MIT team has formed a company, Covalent Solar, to develop this exciting and innovative device. This technology may unlock new ways to think about using solar in buildings and home construction.

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