Colorful Glass Delivers Massive Solar Energy Boost
Colored dyes mixed into glass could provide a major boost to a solar cell’s ability to squeeze as much energy as possible out of a beam of sunlight. The technique, discovered by scientists at MIT, shepherds light to the edge of the glass, where it can be collected and converted into energy.
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The secret to affordable fuel-free energy may lie in some pretty-looking glass. Scientists at the Massachusetts Institute of Technology View Image have found a way to use dye-colored glass to harness clean and renewable energy — and to do it in a practical and cost-effective way.
The research, published in Friday’s Science journal, builds off ideas first tested in the ’70s. The work back then, however, never found a way to effectively absorb the light without losing its energy.
Hanging Onto Light
The MIT procedure uses something called a “solar concentrator.” Unlike the 1970s-era devices, this creation is able to grab the light — and then hang onto it. The concentrator can send the light at a much longer distance than past models have achieved, shooting the energy straight into solar cells along the glass’s edge.
“Once the light is trapped inside, a major loss mechanism is that it can be reabsorbed by another dye molecule on its way out,” MIT researcher Jon Mapel — one of the study’s authors — told TechNewsWorld. “Every time that happens, there’s a chance that it can get lost. It ends up going through a loss-absorption-reemission cycle, and eventually you lose too many of them and not enough get to the edges,” he explained.
It’s a problem that’s plagued the field of solar research for decades — and until now, there hasn’t been a strong solution.
“A lot of technology goes into ensuring that the light is transmitted to the edge of the glass panel,” Rob Collins, professor of physics at the University of Toledo, told TechNewsWorld. “Oftentimes, when you illuminate a dye, it will radiate in all directions. What you want to do is capture it within a glass, [and] they have established a way of efficiently doing this.”
The solar concentrator results in 10 times more energy being created than what current systems can provide — and theoretically, it can do it at a fraction of the price.
“Since you’re using a lot less solar cells, you can potentially reduce the cost of solar electricity,” Mapel said.
Homeowner Appeal
The system may also have appeal to homeowners wary of putting huge panels on their roofs. The solar concentrator could actually become part of your house — without any unattractive addition.
“You could do dual-use as a window or skylight, where you have some light passing through but also have power being produced by it. It could be interesting because it would have those aesthetic advantages,” Mapel pointed out.
For people willing to go the full mile, though, the concentrator could double up with a regular solar panel to boost energy efficiency by a pretty big margin.
“A solar panel’s pretty good at absorbing infrared light, but it doesn’t do as good of a job at trapping as much power out of the visible spectrum as it could. You put this concentrator on top, you’d get more power of the visible … and end up with a combined system that could be up to 50 percent higher in power conversion efficiency,” Mapel said.
The MIT team estimates the products could become widely available within the next three years.
Celebrating Success
The research was funded by the U.S. Department of Energy’s Office of Science and the National Science Foundation. The organizations know any scientific study is always a risk — but successes like this one make the investments worth their while.
“When the project began, there [was] no way to know that this would have been one of the end results,” Josh Chamot, a spokesperson for the National Science Foundation, told TechNewsWorld. “It’s very rewarding for us to see these types of research results come out of those sorts of collaborations.”
The findings are equally rewarding for the science community — much of which has waited years for this kind of development.
“It’s quite exciting for us scientists working in that area,” Collins said. “We’ll obviously look at this quite seriously.”
Replies
Thanks. Just passed this on to DW the scientist.
Doesn't take a scientist to offer some critical evaluation. My first though is if you had a multi-layer (laminent) window how could the leading edges provide enough area to capture sufficiently? If the efficiency was increased by 10-fold this would reduce the area need by a factor of ten, BUT that would just make it a breakeven condition?
I think the bigger factor of application is the potential reduction in site-need from the grid back by the appearance that it is well hidden. Yet, how much visibl;e light will be reduced as a result.
I think, and it's before the first java has gone down, that it's saying that the entire window surface is the capture area. Because of the dye application, it's able to send the light further (all the way to the edge), where it's collected by the solar cells there. So you are still getting a 10 factor increase in energy.If you reduced the window size, then you'd be back at zero gain.'Man who say it cannot be done should not interrupt man doing it' ~ Chinese proverb
I tend to agree ... we still have to follow the laws of thermo ... You simply can never get more energy than would fall on the window ... I'm not implying that is what they are saying ... but the other guy did point out the visible light transmittance issue ... the more energy you take out ... the more you don't have for daylighting.
I'm sure this is a very very interesting science/technology ... but I'm guessing far from practical applications in your/my home. Sounds pretty far out to me. I think I've heard of glazing systems that are PV systems in themselves ... i.e. translucent PV panels that double as windows. It's all good research for it leads to better practical products.
Where this would probably make sense is on large commercial buildings, with acres of glass windows & siding.
with acres of glass windows & siding.
having seen this same article about four times now, I'm not sure it is even about "vision" windows at all.
Every time I go back to the source material, it seems to reference how to make stand-alone PV panel assemblies better. Where the "window" comes in still makes no sense.
As a window, from all of the readings I've made so far, you are probably going to get spandrel glazing transmissivty, not the sort of thing the average person might call a "window."
The use in a curtain wall always gets to the complexity of multiple glazing units so that they have any U value at all. Wiring one of the glass planes is not going to decrease that much, which is not going to inexpensive. Which suggests that using PV glazing in a curtain wall might actually have a negative ROI (pick your matrix of "whys" decreased natural light requiring more artifical; coest of glazing versus cost of power; cost of maintaining wired panels right round a building, even on less-sunny surfaces . . . )Occupational hazard of my occupation not being around (sorry Bubba)
Yeah, the guy writing the article may have extrapolated to using the glass in windows, but I suspect the idea is primarily pointed in the direction of dedicated collectors.The thing is that solar cells can tolerate, with good efficiency, sun energy levels about 10x the strength of the noonday sun. Since solar cells are (relatively) expensive, and since the cost is roughly proportional to the area of the cell, it makes sense to use some sort of concentrator to reduce overall system cost per watt.OTOH, the technology of more mundane non-concentrator type solar cells has advanced to the stage where "parity" is anticipated within about 3 years. (Ie, technologies in pilot production, when scaled up, should produce a cost/watt equal to the cost of coal-fired generation.) There are already several large arrays on the grid in Europe.Also, solar-thermal technology has advanced to the point of parity. There are a couple of large solar-thermal arrays online in the US southwest, with more being built about as fast as they can.
Too much sanity may be madness. And maddest of all, to see life as it is and not as it should be! --Miguel de Cervantes
Another link to the same thing:
http://www.inhabitat.com/2008/07/14/revolutionary-concentrated-solar-array-by-mit/#more-12598
In 1965, when I was ten years old, Popular Science and other magazines had articles predicting we'd all be using solar PV panels on our homes within ten years. Now that I'm 53, they're still predicting I'll be using them in just ten years!
At high noon on a good day, Mr. Sun puts about 1000 watts of power on every square meter, or about 93W per square foot. Let's assume this MIT invention gets into production and it's much better than any PV cell ever used here on Earth. I'll be super-optimistic and give it an efficiency of 25%. After the required power inverters and such the net efficiency at the breaker panel might be 20%. So now the 93W Mr. Sun provides is reduced to 19W per square foot.
If the peak demand for a house is 100A at 110V, that's 11kW, so we need about 600 SF of PV windows facing South to keep the electric meter running backwards at high noon. Morning & afternoon? Better double that to 1200 SF. Are those numbers, or even 1/3 of those numbers, practical for residential use?
I think PV technology is great, but IMO the articles portraying small-scale PV applications are misleading at best. Put the damn things in a giant array out in the desert, and stop pretending we can have them on our windows or roofs.
Edited 8/2/2008 7:41 pm ET by TJK
>>If the peak demand for a house is 100A at 110V, that's 11kW, so we need about 600 SF of PV windows facing South to keep the electric meter running backwards at high noon. Morning & afternoon? Better double that to 1200 SF. Are those numbers, or even 1/3 of those numbers, practical for residential use?No, if your assumptions are valid, there is no off-peak storage, and the goal is to provide 100% of residential power in any part of the country.
Personally, I can't get past the cost of what it would take to provide a significant fraction of my household needs. Now, it'd be pretty cool if we could figure out how to use the public street surface as a solar collector, store energy in the bed, and make every road in every neighborhood a power bus. Or something like that.
We have a BP station here in town with a solar canopy. If someone wouldn't have told me what it was, I never would have guessed they were solar panels.
jt8
"A little 'enthusiasm' and all problems seems small!"