The vast amount of glass in skyscrapers and office buildings represents enormous potential for an emerging technology that turns windows into solar panels. But major questions remain as to whether solar windows can be sufficiently inexpensive and efficient to be widely adopted.
If you picture the glittering glass skyscrapers that dot America’s cities, it becomes clear why the idea of using that vast window space to generate solar power is gaining traction. In 2009 alone, 437 million square feet of windows were installed in non-residential buildings in the United States. That many square feet of standard solar panels would generate around 4 gigawatts of power, roughly the total installed solar capacity in the U.S. today.
Such potential is leading engineers and entrepreneurs to more intensively explore the idea of turning windows into solar-power producers. Solar windows, a subset of the growing field known as building-integrated photovoltaics, are based on the concept that a window doesn’t need to be 100 percent transparent, and a solar panel doesn’t need to be 100 percent opaque. Several ways currently exist to turn a window into a power-generating device, from thin-film silicon, to dye-sensitized solar cells, to tiny organic cells.
Some experts think the field is poised to take off, and although the world may not see an all-solar skyscraper for a while, a number of companies are promising commercial-scale production of various solar windows in the next two years. Still, the cost and technical hurdles facing this fledgling technology could get in the way of a future filled with towering, emission-free power plants. Like other cutting edge alternative energy sources, energy-generating windows could become a mainstay of a greener future in the coming decades, or they could prove to be impractical and produce only a fraction of solar-powered electricity.
“The challenge is whether you can get the cost down and the electricity generation up,” says Sarah Kurtz, a scientist with the U.S. government’s National Renewable Energy Laboratory (NREL) in Colorado. “There are lots of different schemes and strategies, and creativity will be the name of the game. If you can get the cost to the place where those windows don’t really cost any more than conventional windows, it obviously makes sense to go ahead and have your windows generate electricity.”