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Researchers at MIT have created a new way to harness the sun's energy - by turning windows in big buildings into solar panels. The new technology, dubbed solar concentrators, harvests light over a wide area such as a window pane and then concentrates or gathers it at the window's edges, said Marc Baldo, a professor at MIT and head of the effort. Three members of the research team, which is publishing its findings in Friday's edition of Science, are in the process of incorporating a startup called Covalent Solar to develop the technology. The team has spent two years identifying organic dyes, painted onto glass or plastic, that can effectively concentrate the sun’s light onto solar cells, enabling them to produce more electricity from fewer cells.

The dyes basically reflect the light (technically, it’s actually absorbed and then sent back out), so that some of it is trapped inside the plane of glass, said Jon Mapel, a member of the research team. With the help of a scientific principal called "internal refraction," which is the same principal that keeps light trapped in optical fibers, the light bounces to the edges of the glass, which have been equipped with strips of solar cells that convert it into electricity.

Baldo added that the technology also could be used to soup up more traditional solar panels, increasing their efficiency by 50 per cent. Solar panels are semiconductors (often found on rooftops) that transform sunlight into electricity. "The sun is an inexhaustible source of clean power. The major impediment to widely deployed solar-power systems has been cost," Baldo told Computerworld. "If you have a big building, you should be able to generate 50 to 60 watts per square meter. The thing with windows is you need a large area of windows. It makes a lot of sense with tall buildings or really big buildings."

With companies looking to go green and cut down on the amount of money they're spending on energy, solar power is gaining attention. And this advancement could help major buildings with lots of windows generate some of their own electricity. Instead of covering a roof with expensive solar panels, the new solar cells only need to be around the edges of a flat glass panel. The concentrated light increases the electrical power obtained from each solar cell by a factor of more than 40, noted Baldo.

Taking technology from the lab to the market can be a daunting task, and Covalent still has many challenges to work out. According to the research the team is publishing in Science, the technology only increased a thin-film panels’ efficiency by 20 percent in tests. And without being paired with a panel, the coated glass only converted 6.8 percent of the light that hit the surface of the concentrator. Another problem is that one of the dyes used in the study has demonstrated a life span of about 10 years. Come rain, snow or unrelenting heat, a solar system has to be able to handle all that nature can throw at it – at least for as long as the warranty lasts. Most of today’s solar panels come with 20- to 25-year warranties. So one of Covalent’s challenges will be to identify dyes that have longer lifespans and can still boost efficiency. Another challenge will be to demonstrate that the technology can live up to the solar industry's expectations, Mapel said, and that means figuring out more mundane things like the proper encapsulation and packaging of their technology.

While the work is being touted as a way to turn windows into solar power generators, Baldo said that traditional solar panels on rooftops still provide the most energy. Using the solar concentrators in window panes is a less expensive alternative. Because the system is relatively simple to manufacture, MIT reports that it could be implemented within three years.

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Photos courtesy of Donna Coveney/MIT and eFluxMedia

Original Source: ComputerWorld and Greentech Media

Related articles: MIT opens new 'window' on solar energy (with video) and Fact Sheet: MIT's solar concentrators