EnergyGlass: Windows that make solar electricity
Almost 90% of electricity generated from the sun comes courtesy of roof-mounted panels made with silicon, according to the National Renewable Energy Laboratory in Golden, Colo. But new technology using clear glass offers another option.
EnergyGlass, based in Riviera Beach, Fla., sandwiches a sheet of polycarbonate laminate infused with nanoparticles between two pieces of optically clear glass. When it comes into contact with various types of light, the light is directed to the pane's perimeter, where it's converted into electricity in the frame of a window or door.
The glass can convert sunlight, ambient light and artificial light into electricity, according to Saf-Glas, a 15-year-old manufacturer of bullet- and blast-resistant safety glass. The company introduced EnergyGlass last year for commercial projects, such as high-rise office buildings and hotels, that are already using significant amounts of clear plate glass.
Vertically mounted EnergyGlass generates about a third as much power per square foot as traditional photovoltaics, the company said. The advantage of EnergyGlass is that it generates electricity in spaces that otherwise wouldn't.
"Architects and designers and construction managers can use this like any other piece of glass. We can make this any size or shape, and it goes where regular glass would've gone anyway," said Steve Coonen, EnergyGlass chief technology officer. "We're taking advantage of the cost of the glass already going in and the labor to put it in. You don't need a rack to hold the solar panels because it's already part of the building."
The technology used in EnergyGlass is known as a luminescent concentrator, so called because "small particles in the glass absorb the light and reluminesce," said Sarah Kurtz, a spokeswoman for the National Renewable Energy Laboratory.
Kurtz said the efficiency of luminiscent concentrators still has a ways to go before they are as efficient as silicon and cadmium telluride photovoltaics. It's a "difficult technology" that will take a few years to develop to become cost effective, she said, but "if you can take light that would otherwise result in heat load from the building and turn that into electricity, that's a win-win for everybody."
Coonen said a 30% federal tax credit and the fact that EnergyGlass simply substitutes for another type of glass make the product competitive in price to standard rooftop photovoltaics. So far, the company has installed the glass in two buildings: a government building in Taiwan and an office building in Delray Beach, Fla. A few other projects are slated for completion in South Florida.
-- Susan Carpenter
Photo: A buildling in Taiwan outfitted with electricity-generating EnergyGlass. Credit: Saf-Glas.