New thermochromic windows that function as photovoltaics have been developed

These photovoltaic windows were an accidental discovery at the National Renewable Energy Laboratory (NREL)

These photovoltaic windows were an accidental discovery at the National Renewable Energy Laboratory (NREL)

A window that dynamically responds to sunlight by transforming from transparent to tinted while converting sunlight into electricity is the new, innovative way to capture solar energy. A team of researchers at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) recently developed the photovoltaic window while working on finding new ways for homes and buildings to harness more solar power with existing technology. “This was somewhat of an accidental discovery maybe about a year ago,” said Robert Tenent, a member of the team. Their work was published last month in Nature Communications under the title “Switchable Photovoltaic Windows Enabled by Reversible Photothermal Complex Dissociation from Methylammonium Lead Iodide.”, while the research was funded by the Solar Photochemistry program within the Department of Energy’s Office of Science along with contribution from NREL’s Directed Research & Development program.

Thermochromism

Thermochromic technology has already been used in products such as mood rings, dyes and window tint, but it is the first time that researchers managed to convert the solar energy into electricity (a solar power conversion efficiency of 11.3% has been established according to the researchers). As the window darkens, it generates electricity, while the color change is driven by molecules (methylamine) that are reversibly absorbed into the device. When solar energy heats up the device, the molecules are driven out, and the device is darkened. When the sun is not shining, the device is cooled back down, and the molecules re-absorb into the window device, which then appears transparent. “When the color of the window changed, it was still an active solar cell collecting energy,” said Tenent. “The technology behind this is some of the highest performance solar technology available today.” The prototype allows an average of 68% of light in the visible portion of the solar spectrum to pass through when it’s in a transparent, or bleached, state. When the window changes color—a process that took about 3 minutes of illumination during testing—only 3% is allowed through the window.

Commercialization of the technology and future applications

During a two-month program called Energy I-Corps, the commercialization of the technology has been explored in order to develop viable ways to reach the marketplace. For this reason, Lance Wheeler and Robert Tenent, the program lead for window technology at NREL and co-author on the paper, have also developed a market strategy for a product they called SwitchGlaze. They hope that the technology –although it is still very new and under development, with a still-unknown cost in mass production- will eventually be integrated into vehicles, residential and commercial buildings, and beyond.

Source: NREL news