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."

Oh, Is It That Time Again?

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.

Re:Oh, Is It That Time Again?

The headlines should read

Energy Crisis Solved Third Time This Week!

right above

Cancer Cured Seventh Time This Year!

Re:Oh, Is It That Time Again?

the truth is the energy crisis *is* solvable, but the bureaucracy responsible doesn't have any incentive to implement the solutions.

Re:Oh, Is It That Time Again?

Okay, just being contrarian, but in a free-market society, what bureaucracy is responsible for implementing solutions? I thought the market would demand, and businesses would respond?

Granted, government can do a lot to encourage the growth of a new industry, but is it really government's job to produce industries?

Re:Oh, Is It That Time Again?

Government solutions give us things like minimum requirements of corn-based ethanol in your gasoline because: Nothing is quite as intelligent as using your food supply to haul Chinese made goods around the country.

Re:Oh, Is It That Time Again?

but in a free-market society, what bureaucracy is responsible for implementing solutions?

That bureaucracy would be the government. Not because they want stop solar, but because they feel the need to intervene where certain crucial resources are concerned because you can't have retired Floridians that live on fixed incomes dying because they can't pay the electric bill and keep the AC running. I'm not saying that my example is a likely outcome of an unregulated power market, but it is most certainly an example that is used in making sure that the power market stays regulated. California has struggled with an unregulated power supply industry. [spur.org] All argument about the pluses and minuses of government regulation aside, the fact is that in most places electricity is a regulated utility and that serves to help contain fluctuating costs and ensure a steady supply. That government assurance lessens the attraction of being energy self sufficient, and that lessened desirability fails to counterbalance the added costs and maintainance of home solar, for most homeowners. If electricity were seen less as a city supplied utility and more of a commodity with many consumer options (like gasoline or groceries) I think that the public interest in solar would be much higher and the available solar products would be more refined.

CA deregulated electricity?

California has struggled with an unregulated power supply industry. [spur.org]

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 [wikipedia.org]. Then transmitters were barred from raising rates but generators weren't.

Falcon

Re:Oh, Is It That Time Again?

All sentences in the linked article are artfully crafted to contain snippets like 'increases power', 'decreases cost'.

However the linked movie [mit.edu] is fairly insightful.

What they're saying is: we absorb light in the coating. Most of then energy that's absorbed is transmitted through the glass to the frame, where it is converted into electrical energy. This idea is from the '70s, but advances in the materials used have improved the efficiency.

Nevertheless, no word is uttered on any practical installations, nor is there any mention of the efficiency compared to the most efficient currently available system, which is very suspicious.

If this becomes popular and oil prices go up, you better get used to living in an orange environment.
Since this coating absors mainly non-orange, it might be possible to combine this with greenhouses. The plants get the orange light and the coating takes the rest.

Re:Oh, Is It That Time Again?

"The plants get the orange light and the coating takes the rest."

Most of the photosynthetic response curve is in the blue and red areas, orange is actually pretty low in the curve and thus many plants do not use that wavelength.

Re:Oh, Is It That Time Again?

oil prices don't have a whole lot to do with the price of electricity.

They will if coal to gasoline ever takes hold. [anl.gov] Every dollar that oil rises makes that more likely, and once there is a huge new demand for coal prices for electricity from coal powered plants will rise accordingly. Coal accounts for 49.7% of US electrical power. Coal and oil will also begin to effect each other if/when electric commuter cars become common. I admit that I only present ways in which oil prices might effect electricity prices, but I think they are both distinct possibilities in the near future. (kinda like every new solar break through we read about)

nuclear power

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 [sciam.com] could provide 69% of the US's electrical needs. Wind [nrel.gov] 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 [orionmagazine.org] 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 [energy.gov]. Geothermal sources produced about 13,000 gigawatt hours [ca.gov] 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

Re:Oh, Is It That Time Again?

I've never really gotten the connection between oil and electricity if someone wants to fill me in?

If oil were free, then all electrical power would be generated from oil. If electricity were free, then oil use would be near-zero because people would be cracking H2 in their homes to fill their hydrogen powered vehicles. That there is a current situation where a small amount of electricity is powered from oil (I'm in Alaska and the vast majority of area covered by power lines is powered by oil, but we are an exception) is mainly because of the economics where oil is a better mobile fuel than coal, and coal is cheaper for generating electricity. If all oil were gone tomorrow, we'd be generating gasoline or diesel type liquids from coal, and coal prices would jump and so would electricity because of it. They aren't linked in that oil goes up $1 and so does electricity. But large changes in price either way will change the demand for the other (with significant market delay when it comes to getting electric or plugable hybrids, but it is happening now none the less).

Re:Oh, Is It That Time Again?

NanoSolar was all over slashdot for quite some time... (they basically print solar panels on flexible plastic). They are much cheaper than regular solar panels (although much less effecient per sq. meter, but the cost/watt is still cheap) You can now buy them. However, their production capacity for the next few years is already purchased, so you might find them from a distributor, if you know someone who knows someone..

Re:Oh, Is It That Time Again?

Um, if you were paying attention, there's another announcement from some company about their revolutionary increases in solar efficiency every couple of months. They're always 'hopeful' it will be in production 'in a few of years'. It never quite manages to materialize. That is what GP is bitching about (quite justifiably).

from the FAQ

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.

None of it will matter

once we reach peak solar in 2015.

Re:None of it will matter

It certainly wont matter to me - I'll be completely converted over to Vetrolium by then.

Re:None of it will matter

That's an ambitious plan. Have you already started decaying?

And When Is It Available Really?

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.

No, you don't have to track the sun.

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

Pure dark

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.

4 vs 40.

FYi, its 40 time better than standard solar cells and 4 times better than their previous results.

The reference from the FAQ
1. Currie, M. J., Mapel, J. K., Heidel, T. D., Goffri, S. & Baldo, M. A. High-efficiency Organic Solar Concentrators for Photovoltaics. Science. In Press.

Re:Factor

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?

Re:Factor

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.

Re:You need to increase them by three times that

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 [nrel.gov]