A team of researchers at Michigan State University in East Lansing say they have developed a solar window with the potential to reduce a building’s cooling needs, as well as provide power.
Solar windows are not new, but the Michigan researchers say their new material is transparent and more appealing for wide use.
- The researchers say the material has an efficiency of 0.5% but they are on a path to reach efficiencies of 4% in the next few years, which could hasten wider adoption.
Solar windows are not new but they tend to have a brown or reddish tint that makes them aesthetically unappealing and reduces their uptake in the market. Now, a team led by Richard Lunt, a chemical engineer from Michigan State University, has published a paper in Joule that demonstrates the use of halide perovskites in absorbing the sun's ultraviolet (UV) light as part of a transparent product.
Replacing windows with solar cells would open a new market for solar energy, one with vast potential because the surface area of windows is so much greater than roofs. However, the perovskite material Lunt has developed produces a small amount of electricity — its efficiency is 0.5%, not enough to generate a meaningful amount of energy, but enough to trigger reactions that darken the window cutting down on the heat it allows into the building, which reduces the load of air conditioning systems.
Buildings account for 40% of the energy use and 75% of the electricity use in the U.S., so a material like this could make a big dent in the country’s energy sink, Lance Wheeler, a materials science researcher at the National Renewable Energy Laboratory, told Utility Dive.
An efficiency level of 0.5% is far below the efficiency of crystalline silicon cells and of other types of perovskite cells, which have been able to reach efficiencies of 22%. But Lunt said it is high enough to provide power to darken glass on demand, which could further reduce demand for air conditioning.
Lunt said his team could push the material to achieve efficiencies of 4%, which could enable the transparent photovoltaics (TPV) to supply energy to the building as well.
“It would be hard to displace an incumbent technology like silicon,” but TPV could serve a new market, Wheeler said. The world is urbanizing and modern cities have a lot of glass and a lot of vertical surface area, he said.
Lunt said the material could be used as smart windows on office buildings, homes, vehicles, greenhouses and mobile electronics.