Power-Generating Windows

A new solar cell material could dramatically reduce utility bills by turning windows into solar panels. In initial testing, the transparent polymer film converted up to 9 percent the energy received from sunlight into electricity, while allowing 25 percent of visible light to come through.

The film was constructed using polymer solar cells, a type of organic photovoltaic cell. Although they’re not as efficient as silicon-based devices, organic solar cells are lighter, less expensive to produce, and potentially disposable. Their optical absorption is also higher, so it takes very little material (on the order of hundreds of a nanometer) to absorb a lot of light, enabling them to be made transparent to some extent.

On the downside, the developers acknowledge that, in addition to lower efficiency, instability due to photo-degradation is an issue with organic solar cells. The current useful life is about 10 years. But as research continues, we may someday see homes, greenhouses, and even cars harvesting sunlight to cut power costs.