Four students at the Massachusetts Institute of Technology have developed a dye-based solar concentrator that converts ordinary windows into solar collectors. When the system is integrated with rooftop photovoltaic cells, it could substantially increase performance.

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Nicolle Rager Fuller, NSF MIT solar concentrator does not need costly tracking or cooling systems.

The solar concentrator consists of a mixture of two or more dyes developed originally for organic light-emitting diodes, but industrial pigments also can be used. The dyes are applied to ordinary window glass and act as a wave guide, absorbing light across a wide range of visible spectrum wavelengths. The trapped light is transported across the glass to solar cells at the edges at infrared or nearly infrared wavelengths that cannot be absorbed by the dyes.

The discovery was unveiled on July 10 by students Jon K. Mapel, Michael J. Currie, Shalom Goffri and Timothy D. Heidel, working in MIT’s Dept. of Electrical Engineering and Computer Science under Marc A. Baldo, associate professor. A similar but less efficient technique was developed in the 1970s. “We made it so the light can travel a much longer distance, resulting in a ten-fold increase in the amount of power converted by the solar cells,” says Mapel.

Coated glass can also be integrated into rooftop photovoltaic cells. “We project the technology can support up to a 50% increase in power-conversion efficiency,” says Mapel.

“What we have created is something in between a window and a solar cell that can function as both and can be tinted to whatever color you want,” says Baldo. The perimeter cells are made from semiconductors connected to wiring imbedded in the window frame. He says conventional solar photovoltaic concentrators need mechanical tracking and cooling systems, while their system requires neither.

Mapel, Currie and Goffri are forming Covalent Solar to further develop their product. “Ultimately, our goal is to reduce the price of solar power, bringing grid parity with fossil power,” says Mapel.