Future solar panels might be invisible and plastered on the sides on buildings instead of roofs. A new startup called SolarWindow makes transparent coatings that turn windows into mini power plants.
On a skyscraper, where rooftop solar panels can only provide a fraction of the massive amount of energy that big buildings use, the new windows could power a much larger chunk of an electric bill.
“Rooftop space available for conventional PV is so limited it is difficult to generate meaningful energy for a skyscraper,” says John Conklin, the startup’s CEO. “SolarWindow, on the other hand, is developing its transparent electricity-generating coatings for the vast surface area of glass available on a skyscraper.”
Installed on four sides of a 50-story building, the windows could cover about six acres of glass and generate 1.3 gigawatt-hours of energy. The company calculates that the system could fully pay for itself in a year, far faster than rooftop solar.
It isn’t the first transparent solar technology in development, but it would generate more power than predecessors. A different solar glass, from Michigan State University researchers, has a power conversion efficiency of just 1%. SolarWindows, which use multiple layers of liquid coatings, produce 53% more power, according to an independent test by the National Renewable Energy Laboratory.
The technology they use–a particular type of organic photovoltaics–also works in less sunny spots and even in shade, unlike normal solar panels. “Conventional PV modules require nearly direct, intense sunlight before they start outputting energy; they have a high threshold for power generation,” says Conklin. “OPV, on the other hand, requires very little amount of light to be absorbed to produce electrical energy.”
Ultimately, the company envisions the windows covering skyscrapers everywhere. In the U.S. alone, an estimated half billion square feet of glass is installed on tall buildings every year. Eventually, the technology may also show up in other products, like glass on the front of a mobile phone that could power the electronics inside.
“In bringing SolarWindow products to market, we envision a world where economics, environmental benefits, energy conservation, and renewable energy are in absolute balance,” says Conklin.