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Researchers Improve Solar Cell Performance
Vegematic writes "Researchers at MIT have improved solar collectors using dyes. They just increased their performance results by a factor of 4. These paint-on materials can increase the power obtained from existing solar cells by a factor of over 40 without needing to track the sun. 'By collecting light over their full surface and concentrating it at their edges, these devices reduce the required area of solar cells and consequently, the cost of solar power. Stacking multiple concentrators allows the optimization of solar cells at each wavelength, increasing the overall power output.' There is also a shorter FAQ available."
You know, when they post another story about the incredible discoveries in solar power that seem to never actually make it to those of us who would be interested if it was cheaper and more efficient..... Show me a company that is already selling this stuff and then I'll be interested.
RTFG - Read The F#$%ing Google!
Why did LSCs fail in the 1970's? Two reasons: the collected light was absorbed before it reached the edges of the glass or plastic plates, and the dyes were unstable.
What about stability? We tested one of our devices and found that it was stable (to 92 percent of initial performance) for three months. This isn't good enough yet for products but we are confident that the technology developed for organic light emitting devices (OLEDs) in televisions will be portable to this application.
once we reach peak solar in 2015.
http://twitter.com/OLDTELEGRAM
I have heard about a ton of solar technologies in the last 24 months that are supposed to revolutionize the way we get energy.
However, I don't see a product.
This is an uber product. The ability to generate electricity up to 40 times the amount of existing solar while allowing as low as 10% of the light to enter?
Commercial Buildings? This technology is off the hook. It not only generates electricity, it SAVES electricity being used to cool the building.
I am sure this would be used on new and existing residential buildings as well. The ability to create skylights while providing power?
I hope this one actually makes it to the market within 5 years.
If solar cell efficiency actually increased a mere 1% for each story slashdot has posted regarding solar cell improvement, then panels would be generating electricity in complete darkness by now.
Better known as 318230.
The quoted factor of 40 improvement is a comparison against unconcentrated solar cells, which nobody uses. At present, all the solar generating plants in the world use mirrors to concentrate the sunlight on the solar cells, thereby greatly increasing performance.
The "factor of 4" improvement refers to how much they've improved over their previous results; it does not refer to an improvement over currently-deployed technology.
But the question is, how much does this technology improve performance relative to currently-deployed mirror concentration? And, what is the cost relative to currently-deployed mirror concentration?
Here is a link to the actual paper published by the MIT team:
http://www.sciencemag.org/cgi/content/short/321/5886/226
So this would imply a new way to recharge an electric car during long drives? Just install them in each window and let the car recharge on the go. The alternator of the future!
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Every time there is a discussion about solar, someone comes on and begins to spout the usual nonsense that the panels never produce as much power as they use during production, a claim that has been disproven repeatedly. Given that this time it was an AC shows that the message might be getting through. Avg payback in energy for crystalline-silicon PV systems is 1-4 years. On a product that is warrantied for 25 years and expected to last well beyond 50 years. http://www.nrel.gov/docs/fy99osti/24619.pdf
While it's great that we have an improved solar cell film, the reality is that, for the most part, the most efficient method used on a practical worldwide scale involves passive solar heating, especially for providing heating and hot water.
Part of the problem is that the manufacturing process - such as that used by Sony in cranking out OLEDs (which they build at the same plant as their photovoltaic solar cells) - causes a fair bit of pollution, both thru film extrusion, bonding, and the doping process.
By 2020 we may see some useful scaled implementation of photovoltaics, but it's still projected that the vast and overwhelming majority of growth in solar will be it's use in passive solar heating (and cooling, using heat exchangers) and in passive solar water heaters, as both such uses have little in the way of pollution in the manufacturing process and have an easier permitting process for factories, installation, and residential and commercial use, and easier to develop tax incentives for on the local and national scales worldwide.
-- Tigger warning: This post may contain tiggers! --
Right, most of the trucks driving around in a Solar Farm aren't replacing hydraulic pistons (which operate at one cycle per day).
The trucks are cleaning the surfaces. This technology won't require cleaning because why?
They have achieved 40x concentration; but there is no cell currently manufactured which is cost competitive at 40 suns. If you find one - there are hundreds of ways to concentrate light to 40x.
The reason concentrators are 1000x is because that is precisely where III-V cells are most economic.
Also no discussion of module efficiency. This puts the tech in a class with nanotech, which are equally quiet about their efficiency.
Indeed the disturbingly inaccurate use of the term effeciency by the author suggests a weak grasp of the subject.
Well no, the angle doesn't change the amount of energy hitting the panel. What it changes is how well the semiconductor solar cells can convert that energy. You don't have to track with these panels because the organic film absorbs, then re-emits the light, and due to the nature of the molecules, it always re-emits the light in the same direction, regardless of the incoming angle. The classic semiconductor solar cells themselves, attached all the way around the edges, are the devices that are sensitive about angle. They receive light at their optimal angle always, emitted from the organic film on the plates, rather than directly from the sunlight.
You lose efficiency in the absorption and re-emission process, but that loss is apparently worth the cost of admission, if these guys have done their math right. Being from MIT, we can hope they can do math.
This technique has a whole host of advantages over classic off-the-shelf panels you can buy today, which the article didn't go into.
The panels you can buy today are very sensitive to shadows. Each cell produces only so much voltage. To get a useful voltage out of them, you have to wire them up in series. If some percentage (50%) of a row is shadowed, the panel will actually effectively shut itself down, and produce no power at all, because of the non-participating cells. (The shutdown is accomplished with passive circuitry, not some sort of machine or processor.) This means that in a typical residential situation, you can't have so much as a chimney on your roof, or your panels could become very expensive powerless decorations. You certainly can't have any trees that could even partially shade your roof. This concept eliminates that problem. The organic molecules in question are very egalitarian about how they re-emit what they absorb. It gets spread out evenly, all the way around. This means that if any portion of the panel is shaded, all of the semiconductor cells still get a lot of (concentrated) light, and it takes a lot more shadow to shut them down.
Another issue with modern panels is the fact that a classic semiconductor solar cell is useful only through a very narrow band of wavelengths. Sunlight is very broad band light. (No jokes about bitrates, thank you.) It shows up at your roof in all kinds of frequencies. The panels you can buy today ignore a large fraction of those frequencies, since they only work at what they're tuned for. However, in the process of ignoring the other frequencies, your standard cell also blocks them entirely. So even though you can manufacture semiconductor cells with different bandgaps that will absorb different sunlight frequencies, you can't stack them directly on top of each other and gain anything. The uppermost in the stack shadows all those beneath, so they're pointless. An older slashdot story about how to manufacture a multi-bandgap semiconductor cell was posted a while ago, but that's still in early research stages too, and it apparently involves fairly difficult semiconductor manufacturing techniques. These panels do an end-run around that problem. Different dye coatings absorb different frequencies of sunlight and DON'T block the remaining frequencies. They pass through. So you can stack concentrator panels, up to some limit, and each one has semiconductor solar cells around the edges specially tuned to utilize the light frequency the dye emits. This is the big win, and the cause for the whopping efficiency claims. The transmissiveness of these concentrators for frequencies they're not tuned for means you can make a sandwich out of them and the resulting panel can use many more frequencies out of the same square meter. There's probably still some limit to how many layers you can stack before you're wasting your efforts, but it's enough to be worth the trouble.
Lastly, classic semiconductor cells can be manufactured specifically to operate efficiently in concentrated light vs standard out-of-the-sky sunlight. That's the reason for the Fresnel lens panels that have
California has struggled with an unregulated power supply industry.
CA didn't really deregulate electricity, power, they shifted the regulations. Before, the same company could own both power generation and power transmission. but when the so called deregulation came it split generation and transmission, a company wasn't allowed to do both. Then transmitters were barred from raising rates but generators weren't.
Falcon
Should there be a Law?
A massive country wide nuclear power plant building spree would need to take place. Right now we have over 100 nuke plants that supply 20% of our electricity
Nuclear power isn't needed. By 2050 solar power could provide 69% of the US's electrical needs. Wind can also supply a lot, I read where the Rocky Mountains alone contain enough potential wind power to supply the lower 48 states but I didn't find a reference. Then a lot of waste heat goes up smokestacks daily. Here's a quote from TFA: "Here's a Maxwell House coffee roaster in Duval County. They're roasting beans, so all that heat has to go somewhere. About twelve megawatts' worth of potential electricity is going up the stack." In Hawaii about 30% of the big Island's, Puna, is from geothermal power. Geothermal sources produced about 13,000 gigawatt hours in California in 2007, with more available.
Add all these together and every coal fired plant should be able to be closed without any more nuclear power plants being built and still have plenty of electricity.
Falcon
Should there be a Law?