The National Renewable Energy Laboratory (NREL) just revealed a new prototype of a solar-powered “smart window” that could provide 80 percent of electricity needs in the United States. The NREL smart window has an efficiency rating of 11%, and it’s actually able to lower building temperatures by changing tint. Upon shifting to the darker tint, the smart window begins generating energy. “There is a fundamental tradeoff between a good window and a good solar cell,” said Lance Wheeler, a scientist at NREL. “This technology bypasses that. We have a good solar cell when there’s lots of sunshine and we have a good window when there’s not.”
The smart window’s functionality depends upon advanced materials such as perovskite, a calcium titanium oxide mineral that is able to absorb sunlight and generate electricity, and single-walled carbon nanotubes, microscopic structures with incredible strength. While existing solar windows are typically not responsive to changes in sunlight, thus remaining at one set level of transparency, NREL’s prototype breaks new ground by demonstrating a dynamic ability to react to light conditions.
The window’s ability to transform is made possible by molecules of methylamine, which move in and out of the window depending on the circumstances. When the sun heats up the window, the molecules are absorbed into it, darkening the window. When the sun is not shining directly on the window, the molecules are expelled, which makes the window transparent. In its solar panel form, the smart window has been able to achieve 11 percent efficiency in capturing solar energy and translating it into electricity. The research team at NREL believes that their smart window design could be used to charge mobile devices and on-board electronics such as fans, rain sensors and motors. While research is ongoing, the team is already focusing on how their design could be commercialized and made available to the public.