Just one percent of the sun’s rays could power the entire planet. Is this technology going to help us use it?
Solar windows haven’t been an attractive addition to homes or commercial buildings due to a lack of progress in solar technology. You could either have a great solar cell or a shabby-looking window, covered in a dark film, but with NREL’s latest development, you’ve got a great window on sunny days, and a great solar cell too, that darkens and lightens with the intensity of the sun’s rays.
Scientists at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL), have learned how to switch a window from tinted to transparent, while converting sunlight to energy.
Using advanced materials such as perovskites and single-walled carbon nanotubes, the new technology responds to heat by transforming from transparent to tinted. As the window darkens electricity is generated. On super sunny days, the windows can grow slightly darker, while using all that sunlight to power your home or office, instead of simply pulling down a conventional window shade, and blocking out the sun.
Perovskites are thermochromatic – meaning the material can change color from clear to tinted with the presence of heat. “There are thermochromic technologies out there but nothing that actually converts that energy into electricity,” NREL scientist Lance Wheeler said in a press release.
As the NREL website explains,
“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.”
This allows 68 percent of the sunlight that hits a window to be transformed into usable energy, without sacrificing visible light that offers natural illumination for the people inside.
“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 paper presenting this idea titled, Switchable Photovoltaic windows enabled by reversible photothermal complex dissociation from methylammonium lead iodine, and published in Nature, states that the windows achieve a groundbreaking 11 percent efficiency. The technology allows for a move to 68% visible light transmittance when the windows are untinted.
The fact that they dim with bright sun, also means that people living in warmer climates could benefit from passive heat regulation caused by the dimming of the windows, as well.
Using simple laws of thermodynamics, nanotechnology, and advanced solar utilization technology, we could start putting windows in our homes, offices, and even automobiles that help to power our lives with the rays of the sun.
Along with solar roofs being offered by Tesla at prices advertised to be lower than a traditional roof, soon every surface of our homes could be producing free, sustainable, non-petrochemical based energy for everything from lighting the dining room table to washing and drying our clothes in the laundry room.
Is the revealing of technologies like these the very beginning of free energy for the masses? In the immortal words of Elvis Presley, “Truth is like the sun. You can shut it out for a time, but it ain’t going away.” It isn’t zero point, but the sun could power our entire planet for eons even if we only used 1% of its energy. So –this is indeed a good start.