Canada's Condominium Magazine
Every day, sunlight falls on billions of square feet of windows on buildings all around the world, and every day, people behind those windows pull blinds and curtains and shades to keep the light and heat out. But all that solar energy, wasted for the most part, could be used to make electricity. All it would take would be converting those windows into solar panels, with photovoltaic cells. With every window creating electricity, there would be less need for rooftop solar panels, and buildings could move closer to becoming carbon neutral. It’s an idea that has been circulating for a number of years now, but two drawbacks have stood in the way, one aesthetic, the other physical.
The aesthetic problem is obvious: ordinary solar panels are ugly, and they are not transparent. Filling windows with conventional panels would be a non-starter. No one would want them.
The physical problem has always been that conventional photovoltaic cells are just not very efficient at converting sunlight into electricity. The best efficiency achieved so far is around 20 per cent, which is why solar panels have to be deployed in such huge arrays to generate utility-scale power.
The big challenge, therefore, has been to improve the appearance of solar panels and at the same time improve their efficiency. And it seems we are now closer to meeting that challenge.
Students at Western Washington University (WWU) have been using a $75,000 grant from the Environmental Protection Agency (EPA) to further develop their prototype transparent “smart solar window.” The glass is clear and harvests ultraviolet light, which is invisible. It is reported to be the first transparent window capable of harvesting solar energy. The student developers are saying that the power generated from smart solar windows could save up to 30 per cent on a building’s heating and air-conditioning costs. While there are other windows that can produce electricity, the Washington team says they are more expensive and more inefficient.
The WWU team are confident that their solar windows will be in buildings in as little as a year from now.
In a separate development, a company called SolarWindow Technologies announced that its photovoltaic cells can produce fifty times more energy than ordinary rooftop panels in use today. This is not a technological breakthrough in photovoltaic efficiency, but a simple matter of distribution: solar windows can cover fifty times more surface area on a fifty-storey building.
Claiming to be makers of the world’s first electricity-generating window, SolarWindow says its windows work in natural and artificial light, “even in low light and shade.” It also claims that a single installation could avoid “2.2 million miles of CO2 vehicle pollution.”
SolarWindow plans to bring their power-generating windows to market soon.