Researchers at Michigan State University have created a new type of solar concentrator that sucks up the sun's rays but – and this is the important part – it's transparent. That puts us one step closer to making our windows solar collectors, although we're still not there quite yet.
First off, this isn't the first time we've seen concentrators that can be applied to glass without dramatically affecting visibility. Spray-on cells and thin films and all manner of really cool research projects have attempted to make our windows (or mobile phones, high-rise buildings, you name it) capable of collecting solar power without screwing with transparency. But in order to collect that juice, some of the light has to be stopped from getting through the glass. It's just physics, which is why this new technology from MSU is so interesting.
The team created tiny organic molecules that are embedded in the glass and can absorb particular waves of sunlight, specifically the ones humans can't see.
"We can tune these materials to pick up just the ultraviolet and the near infrared wavelengths that then 'glow' at another wavelength in the infrared," says Richard Lunt of MSU's College of Engineering. "Because the materials do not absorb or emit light in the visible spectrum, they look exceptionally transparent to the human eye."
What's more, these molecules guide the wavelength light to the edge of the glass, where it's then converted to electricity by a normal array of photovoltaic cells. By moving that energy production off the glass, there's no need for wires or other hardware embedded in glass, impeding the view.
The downside to all this – as always – is efficiency. In its current form, these cells are only around one-percent efficient. Compared to the best colored luminescent solar concentrator, they're down by about 6 points. But Lunt and his team are still plugging away on optimization, and believe they can get to 5 percent efficiency once the technology is fully developed.