MIT team increases efficiency of solar panels

By Carolyn Y. Johnson, Globe Staff

Solar energy, vaunted for decades as the next big energy revolution, may finally get its day in the sun.

A new way to concentrate solar beams that could be used to increase the efficiency of solar panels is being reported by an MIT team today in the journal Science, and this and other technological advances, combined with high energy prices and political initiatives to help promote solar power, are giving the sun a new sheen.

"The question is, can you make a better solar panel that you can put on somebody’s roof?" said Jonathan Mapel, an author of the study and MIT graduate student who has co-founded a startup called Covalent Solar to turn the idea into a product. "The two things that matter are: you want more power output and you want to pay less for it."

The work at MIT could potentially do both, using a simple trick that makes more efficient use of the full spectrum of sunlight.

Typically, solar cells efficiently convert only a portion of sunlight into electricity. But the MIT researchers created a plate of glass that sits on top of a normal solar panel to make better use of a broad range of wavelengths. They deposited a film of dye onto the glass that acts like a sieve -- absorbing light in the visible spectrum and directing it to special solar cells on the edge of the pane that are tuned to convert visible light into electricity. Meanwhile, the rest of the light passes through to the normal solar panel, where it can also be converted into electricity.

In the paper, the scientists demonstrated increasing the efficiency of certain types of solar cells by about 20 percent, but they believe that the system can be tuned to increase efficiency by 50 percent.

Other scientists cautioned that the MIT work was one of many promising technologies seeking to make solar power more mainstream, and that there's no guarantee it will pan out.