Solar windows get better at producing electricity – and at being a window

Global Business

You may have heard of solar windows. They’re windows that harness sunlight for energy. Scientists are making progress on making this renewable resource even more efficient.

CGTN’s Hendrik Sybrandy has more.

Solar windows are not new. They harness a fraction of the sunlight that hits them while still allowing people to look through them. Now scientists in the U.S. state of Colorado have gone several steps further. They’ve developed a window that switches from producing electricity to being mostly transparent.

“The people that are working in this space are generally having to deal with this tradeoff between whether or not you want a decent solar panel or a decent window,” said Rob Tenent, Window Technologies Program Leader for the U.S. Department of Energy’s National Renewable Energy Laboratories.

Tenant said you can have both. Two years ago, NREL Research Scientist Lance Wheeler discovered glass that turned black after absorbing infrared radiation turned clear after it was removed from heat. Why, he thought, not apply that concept to material that converts energy from the sun?

“And now we have what you could call the first switchable photovoltaic window where it goes from a tinted state to a transparent state and now you have a good window and a good solar cell,” said Wheeler.

When sunshine heats the window, gas molecules are released, the glass darkens and generates electricity. When the sun disappears, those molecules are reabsorbed and the window becomes transparent. You can’t do that with current silicon-based solar panels.

“So in this case, we’re able to generate lots of electricity when it’s needed and there’s lots of sun shining and when it’s not you still have a good window,” said Wheeler.

“Anything we can do to mitigate the heat that goes in through those buildings from solar radiation would be hugely impactful on the cooling of buildings which is a large energy sink,” said Nate Neale, another NREL Research Scientist.

The energy savings could be enormous. Scientists believe solar cell windows could work well in commercial buildings. Residential buildings and even automobiles could be good fits as well. The challenge will be scaling up the switchable material from its current centimeter square to something much larger, without losing durability or efficiency. Commercialization is still several years away. The dual-purpose windows could have global appeal too.

“There’s large-scale glass construction worldwide and there’s a lot of growth in areas that have got an awful lot of sun right now,” said Tenent.

Sunlight that could be harnessed in buildings that put that energy to use right away. Without losing the view entirely.