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This Is Why Solar Windows Have Yet to Become Popular

They're just not as efficient as solar panels yet.

by Meredith Rutland Bauer
Dec 26 2016, 3:00pm

Image: SwissTech Convention Center/Wikimedia

The future of solar energy in the U.S. has largely been a vision of panels on every roof and silver fields of solar farms. But what about other surfaces, like windows?

Window pane solar panels don't have a large presence in the solar energy market. But with massive metropolises boasting skyscrapers with thousands of windows each—let alone the half-dozen windows in each home—why hasn't this option taken hold?

The reason boils down to the way solar panels capture energy. Most solar cells are photovoltaic, so they collect energy by absorbing light and then excite electrons to a conductive state. Opaque panels are able to trap more sunlight to convert into energy than a transparent one can—for a few reasons, but if light is brightening a room, it can't also be used for power generation.

Michigan State University researchers made a splash in the green energy world in 2014 when they announced their transparent solar panels—the first ones created—but critics pointed out the panels were only 1 percent efficient, whereas an opaque solar panel is closer to 20 percent efficiency, according to the American Society of Mechanical Engineers.

Since then, just a handful of companies have started selling solar panel windows because of the low efficiency and slow commercial adoption. Meanwhile, rooftop solar panels have made a small, but growing dent in commercial markets, with 1 million homes estimated to have solar panels as of 2016, according to Business Insider.

Solar Window uses a liquid photovoltaic conductor that can be painted onto existing windows of a skyscraper—going for energy reduction en mass, rather than focusing on the efficiency of each individual device.

"Conventional solar systems cannot be applied in this way, and are instead limited to only a handful of square feet on congested rooftops. These very small tower rooftops are often crowded with service systems such as heating, ventilation, air conditioning, and elevators," the company website states.

Ubiquitous Energy uses a similar strategy, applying a solar panel film onto windows that allow 90 percent of visible light to stream past. Its solar panel film absorbs energy from ultraviolet and and infrared light and converts that into energy.

According to the company's website, it is in a pilot production phase and hasn't reached commercial markets yet.

While it may take a while before your home can get decked out with energy-producing windows, the technology is most likely on its way. And this tool may even be able to be adapted so you can install self-changing glass on your phone, which might be the reason this suddenly becomes popular.