Low heat emission glass is known for keeping the heat in and is widely used in offices and residential buildings. According to a study, these windows are found in 80% of all residential buildings and 50% of all commercial buildings in the US. There might be a way to harness electricity from all the energy falling on these windows, which has not been explored before, and National Renewable Energy Laboratory (NREL) might have figured it out with their smart windows.
A team of researchers from the NREL has developed prototype solar-powered smart windows that serves the same function of keeping the heat out of the building but at the same time, converting this heat energy to electricity. These thermochromic (changing color from clear to tinted in response to heat) window make use of the energy harvesting material perovskite. “There are thermochromic technologies out there but nothing that actually converts that energy into electricity,” NREL scientist Lance Wheeler said in a press release.
These smart windows work by the release of methylamine molecules when they are heated by the solar energy. Tese molecules cause the device to darken. The windows are transformed to solar panels during this transformation and can convert solar energy into electricity at 11.3 % efficiency.
“There is a fundamental tradeoff between a good window and a good solar cell,” explained Wheeler, who is a lead researcher in this study. “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.”
All of this sounds promising but there is still a major problem that the team at NREL needs to fix before we can see these smart windows becoming a part of our daily life. A 1-square-centimeter of the prototype device showed a decrease in performance after 20 repeated cycles.
The existing chromatic windows can last through 50,000 cycles and a standard solar panel can keep 80% energy conversion efficiency for 25 years according to Electrek. NREL is currently researching on how to improve the stability of the transformation cycle.
There are huge implications for this research as more and more people are planning to switch to renewable energy technology. This could replace solar panels in buildings and maybe one day replace the car windows for electric vehicles to charge the car on the go.