Demonstration device dynamically responds to sunlight by transforming from transparent to tinted while converting sunlight into electricity
Thermochromic windows capable of converting sunlight into electricity at a high efficiency have been developed by scientists at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL).
Relying on such advanced materials as perovskites and single-walled carbon nanotubes, the new technology responds to heat by transforming from transparent to tinted. As the window darkens, it generates electricity. 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. A video showing the device switch can be seen below.
The NREL-developed demonstration device allows an average of 68 percent 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 percent is allowed through the window. Existing solar window technologies are static, which means they are designed to harness a fraction of the sunlight without sacrificing too much visible light transmission needed for viewing or the comfort of building occupants. “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 proof-of-concept paper published in Nature Communications established a solar power conversion efficiency of 11.3 percent. “There are thermochromic technologies out there but nothing that actually converts that energy into electricity,” Wheeler said. He is the lead author of the paper, “Switchable Photovoltaic Windows Enabled by Reversible Photothermal Complex Dissociation from Methylammonium Lead Iodide.”
His co-authors, all from NREL, are David Moore, Rachelle Ihly, Noah Stanton, Elisa Miller, Robert Tenent, Jeffrey Blackburn, and Nathan Neale.
In testing under 1-sun illumination, the 1-square-centimeter demonstration device cycled through repeated transparent-tinted cycles, but the performance declined over the course of 20 cycles due to restructuring of the switchable layer. Ongoing research is focused on improving cycle stability.
The path to commercialization of the technology was explored last year during a two-month program called Energy I-Corps. Teams of researchers are paired with industry mentors to learn what customers want of the technology and develop viable ways to reach the marketplace. Lance Wheeler and Robert Tenent, the program lead for window technology at NREL and co-author on the paper, teamed up to develop a market strategy for a product they called SwitchGlaze. The effort was funded by the Emerging Technologies program within the Department of Energy’s Building Technologies Office.
Wheeler said the technology could be integrated into vehicles, buildings, and beyond. The electricity generated by the solar cell window could charge batteries to power smartphones or on-board electronics such as fans, rain sensors, and motors that would open or close the windows as programmed.
NREL is the U.S. Department of Energy’s primary national laboratory for renewable energy and energy efficiency research and development. NREL is operated for the Energy Department by The Alliance for Sustainable Energy, LLC.
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An old boss called those things “Laboratory Curiosities”.
Does it work so well when the window is covered in frost or snow?
I’ve invested in a leading commercially available tek over many years : http://www.smartglass.com/ .
With a little smart tech, it could recharge your electric car’s battery while it’s parked for long periods.
If you need to charge your car battery every time you park it you need a new battery.
We already have reliable inexpensive technology to accomplish this called a trickle charger.
This is just a reinvented wheel, only they managed to make it more expensive and less reliable.
Not so. You charge your battery whenever the engine is running. But, given the total area available for this “solar cell”, it would need some 200 hours of sunshine to completely charge a discharged battery.
How much of the electricity generated by the alternator get stored in your battery during driving depends on how many systems on your vehicle are drawing upon this energy. Mostly the battery acts as simple capacitance to the circuit providing spike buffering. Once it is completely charged all the excess current merely flows through.
If it is loosing power during when not operating it is because of continuous load from alarms, clocks, etc. If you are finding your car battery drained of power after even for a short time as a week, you have a battery issue or a short circuit in your system.
The thinking is all wrong. It’s not windows that generate electricity we want but bricks, concrete and cladding electro-panels.
And you Sir, are a wise person indeed. The use of solar PV for NON transparent building materials would make way more sense.
A brick, which is able to store ‘heat’ and produce energy, might be an ideal combination….don’t you think?
Mind you, the connections for the thousands of bricks may become a technology limiting issue, but I’m sure that would or could be overcome – but I’m not planning to build my house around any of these technologies, just yet.
The only apparent worthwhile use for energy production from ‘glass’ is in domestic/commercial or industrial windows.
There has to be an area sufficient to produce energy to pay for the cost added to the ‘window’.
This likely use would be limited for several simple reasons…. not all windows face the sun….not all windows would want to be ‘tinted’, for practical and aesthetic reasons….but mainly, as normal glass is in the range of 80 to 90+ % transparent, any reduction , like down to 60% as this glass is said to be in its transparent state, would not be acceptable to most occupants/owners of the buildings.
As a builder/specifier in that industry, I couldn’t and wouldn’t include this feature in any of my buildings. IF I wanted to have sufficient energy production at a ‘reasonable’ price, I would still want a large area which is non-intrusive to the structure and which is specifically designed to produce energy and at as high an efficiency level as is possible, not hamstrung by the need to do another job – be transparent.
Even that said, I doubt I would have the economic justification to add solar PV anyway, if connected to an easily accessible power supply – ie, grid electricity
“but the performance declined over the course of 20 cycles due to restructuring of the switchable layer”
Sorry to sound cynical but sort that little glitch out guys and get back to us. It kind undermines the ‘renewable’ thing. Sounds more like ‘disposable’ like a plastic water bottle. I reckon about 20 refils is their limit too.
“but the performance declined over the course of 20 cycles ”
In engineering speak, it does not work.
Old and boring is low e glass and proper over hand is how you do it. Direct sunlight provides heating in the winter and blocked in the summer.
The purpose of is to enjoy the view.
i buy asian items and when can USA Make something without costing to daen much to buy plus AMERICANS items are junk like old Japan items were
The concept behind eyeglasses that darken was discovered in 1880.
https://en.wikipedia.org/wiki/Photochromism#History
The “History of Science” is good reading.
This is yet another addition to the long list of nutty ecological schemes that are totally mis-directed. Windows are there to look out of, and not only just at night. Windows that go black to produce electricity are better replaced with windows that you can look out of during the day and solar cells on the roof directed at the sun average location. Whether having solar cells to produce electricity is quite another matter for argument.
So, I guess the next step is to cover cities with a “Under The Dome” style covering.
The bottom line is how much does it cost? Glass is a very significant cost in a large multi storey building. This electricity generating glass will obviously add a considerable amount to that cost. It would be a complete waste of money if the same amount of power could be generated by everyday cheap solar panels at a fraction of the cost.
I won’t buy this stupid device, and don’t see anyone who would.
Most windows are vertical, and that’s a terrible orientation for a solar device. Sunshade or curtains do better.
It could make sense to collect the light into electricity when it is not needed in the building, but this must be in human/building control, not heat/sun control, and there’s no need of this 2-in-1 device when a cheap and more efficient second device can be use with a normal window (either inside or outside).
Great idea, even better idea don’t use so many damn energy wasting windows.
Okay…now we are gonna windows for solar panels….that’s kinda…………………………………………………………..cool 😎