Transparent Solar Windows Generate Energy Without Obstructing the View

Windowed buildings could begin generating their own power without changing the architecture. Hey Paul [CC by 2.0]/Flickr

Imagine being able to generate solar energy on the surface of every window or electronic device without obstructing the view. It's possible, thanks to Michigan State University researchers who have developed a completely transparent solar concentrator, reports

The key word to this development is "transparent," according to Richard Lunt of MSU's College of Engineering. Although research into see-through solar concentrators is nothing new, previous developments have failed to produce effective results with material that is truly transparent. Although there have been solar concentrators you can see through, these have always been highly colored or tinted.

"No one wants to sit behind colored glass," said Lunt. "It makes for a very colorful environment, like working in a disco. We take an approach where we actually make the luminescent active layer itself transparent."

Luminescent solar concentrators generate electricity by concentrating radiation — most often, non-ionizing solar radiation. They convert it by luminescence and operate on the principle of collecting radiation over a large area.

The MSU team's breakthrough uses specially-developed, small organic molecules to absorb specific nonvisible wavelengths of sunlight.

"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," Lunt explained.

The "glowing," which does not occur in the visible spectrum, is guided to the edge of a clear plastic panel where it is then converted to electricity using thin strips of photovoltaic solar cells. Current models are only able to produce a solar conversion efficiency around 1 percent, but these are just the prototypes. Lunt and his team are optimistic that efficiencies close to 5 percent will soon be possible. By comparison, the top colored solar collectors operate at about 7 percent, so the technology is not far off from the competition.

"It opens a lot of area to deploy solar energy in a non-intrusive way," said Lunt. "It can be used on tall buildings with lots of windows or any kind of mobile device that demands high aesthetic quality like a phone or e-reader. Ultimately we want to make solar harvesting surfaces that you do not even know are there."