Researchers at Michigan State University say they’ve produced a transparent solar concentrator that can be attached to windows to harness power without losing light or visibility.

The idea of using windows to capture solar energy isn’t new. Rather than the surface of the window being a solar panel, existing technologies use a plastic overlay to harness the solar rays and guide them to thin strips of solar cells around the frame. The idea is to take advantage of the windows on buildings where it would be either impractical or undesirable to have a lot of traditional solar panels.

The main limitation with the existing setup is that the plastic overlay is colored, in turn affecting the color of light that passes through into the room.

Richard Lunt of MSU says he and his team solved this problem by only targeting ultraviolet and near infrared wavelength light. The overlay incorporates organic molecules which absorb this light — and this light only — and then retransmit it at a different infrared frequency to the solar cell strips.

Because none of this light is visible to the human eye, the overlay appears transparent and the light that passes through looks normal.

The cost is in efficiency, however. While a standard solar panel can achieve 15 percent efficiency in turning solar energy into electricity, the existing colored overlays achieve around seven percent. At the moment the transparent overlay only achieves one percent, thought Lunt says that with further work five percent should be possible.

Whether such a system will be financially worthwhile also remains to be seen, though it could make sense on buildings with a lot of windows. Lunt also suggests the concept could be scaled down such that screens on phones or electronic reading devices could harness some solar energy, if only a trickle.

[Image credit: MSU]