Slashdot Mirror
Caltech Makes Flexible, 86% Efficient Solar Arrays
strredwolf writes "Caltech has released a flexible solar array that converts 95% of single-wavelength incandescent light and 86% of all sunlight into electricity. Instead of being flat-panel, they stand thin silicon wires in a plastic substrate that scatters the light onto them. The total composition is 98% plastic, 2% wire — the amount of silicon used is 1/50th that of ordinary panels. So as soon as they can get these to market, solar could be very viable and cheap to produce." Update: 03/01 21:02 GMT by KD : Reader axelrosen points out evidence that the 80%+ efficiency figure is wrong. MIT's Tech Review, in covering the Caltech announcement, says that the new panel's efficiency is in the 15%-20% range — which is competitive with the current state of the art. And the Caltech panel should be far cheaper to manufacture.
Holy balls. If this article is spot on, they've doubled the efficiency of the current technology (which converts at about 40%) AND done it in such a way that the stuff is cheaper to manufacture AND made it flexible. This is the sort of thing that can have a real (and probably positive) impact on the world we know. Amazing. The only remaining question (I didn't see anything about it in TFA) is how durable this stuff is compared to the current panels.
As far as I can figure from the article what is says is 95/86 of the light is absorbed, it doesn't say that all of this light is converted into electricity as is stated here on Slashdot. That is also impressive numbers and very interesting, but my guess is that the efficiency of the solar panel is going to be a lot lower than those numbers posted on the parent, most likely at least a factor 2 lower.
I beg to differ. This is exactly what we should be using our oil reserves for: building up a supply of renewable energy. Look at it this way: we can burn our oil; or we can use it to create systems that will generate energy for us, without needing further input of oil.
I'd dearly love to see us in a world where we no longer need to burn oil or coal for energy, or if we do need to do so, we use oil we've produced ourselves - using only water and carbon dioxide as the essential inputs. On that day, we will have overcome one of the major problems facing our society today.
We'll never run out of plastic. Don't forget that "oil" came from biological sources. It'll be more expensive than just pumping the stuff out of the ground, but as long as there is life on Earth we'll be able to produce all the polymers we need.
How can I believe you when you tell me what I don't want to hear?
I've never had problems with soda bottles...and thats 100% plastic
All your 09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0 are belong to us
How so? The oil isn't being burned, so it's not ending up in the atmosphere.
Or do you think oil is evil even when it's locked out of the biosphere?
Oil isn't bad. The byproducts of burning it are.
And for that matter, you can produce polymers from bio-oil just as well (though not so cheaply).
Meanwhile, Germany (where it is always cloudy, and where the government recognizes the need for renewable energy) is pushing solar like crazy, and Arizona (where it is always sunny, and where the governor has no conception of future beyond a few years) is burning coal.
wtf?
You've never left them out in direct sun for ten to twenty years then.
There's plastic, and then there's plastic. Some modern plastics are quite durable.
Idiots stating stupid facts about light should go to school. Solar cells do not just absorb and convert visible light, they also convert UV and IR light also (which we cant see) 90% of UV still goes straight through overcast clouds.
PhD candidate doing my research in new materials for photovoltaics here.
I'm sick and tired of all this mis-reporting. These are NOT 86% efficient cells. If they were, (and they were inexpensive) it would be the greatest discovery in 50 years and it would have been all over every newspaper in the world 2 weeks ago when this paper was published.
They simply absorb 86% of light that hits them. When you say a cell is X% efficient without qualifying it, it's taken to mean power conversion efficiency [PCE] (optical power in/ electrical power out) That and dollars per watt are the numbers that really matter. Read the Nature Materials paper that drove this and you'll see that theory says this design could be up to 17% efficient. That compares unfavorably to mid to high-end commercial cells on the market today.
I'm not saying that this research is a worthless endeavor, maybe they can hit the maximum theoretically possible PCE and keep the cost down. That might have real-world impact.
The caltech news brief quotes Atwater (the PI for this research) as saying that the photons are not only absorbed, but they're also convertedto charge carriers (which is a good step). The problem he doesn't mention here is, these charge carriers loose all their energy (voltage) before they exit the cell. Solve that problem and we've got a winner.
The fundamental issue with nano-structured designs like this is the surface area of the P-N junctions in them. Large surface area means high dark current which means low voltage output. Low voltage output means low PCE. Unfortunately, nothing in this research solves that problem.
It's EQE is 77-85% (above the band-gap).
It's IQE is 90-100% (above the band-gap).
But it's energy conversion is similar to other commercial panels; about 20%.
High absorption and high QE is not enough to get high conversion rates.
You still have the band-gap (the minimum frequency which a photon needs to be able to free an electron from silicon) which excludes up to 30% of all photons, and almost all photons above the band-gap which do free an electron have more energy than is necessary to do so, so the excess is wasted as heat.
Unfortunately the only things to get excited about here are the low cost and flexibility.
"as soon as they can get these to market, solar could be very viable and cheap to produce." And if a frog had wings his ass wouldn't bump the ground when he hops.
I appreciate Slashdot acting like an old Popular Mechanics here, but I wouldn't get too excited just yet. As somebody pointed out in another forum, when you compare ethanol with gasoline in terms of efficiency, if all we had was ethanol primarily from "corn" (U.S. term, UK term is "maize") and then someone invented gasoline, we would be raving about the improvement in efficiency and economy. IOW, I will believe cheap, efficient solar power when I see it on the neighbor's roof. Until then, this is one more expensive quest for a pot of gold at the end of a rainbow. In the meantime, we could be practicing more energy efficiency.
FWIW, I knew W was full of crap with that whole "hydrogen economy" nonsense back around 2005. That was an absurd sop to deflect a little criticism that he was as much a tool of Big Oil as his Old Man. Make note that I served in Iraq during Operation Desert Storm and when it was over, George H.W. Bush was sitting on a 91 percent approval rating based on a war we had to fight to maintain a steady supply of petroleum for the Western Powers and Japan. From the desert, I wrote my Senators and lobbied them to get a bill going to get us to start weaning off Mideast Oil. That S.O.B. Bush didn't raise a finger, nor did our Congress and eventually Western wealth transfer begat Osama Bin Laden, 9/11, Iraq War II, and Afghanistan. Wouldn't you think a 91 percent approval rating might have been enough political capital to change things a little? It may even have made Bush the Elder seem like the President of the U.S.A. instead of President of the New World Order since he rightfully earned a reputation for being allergic to domestic policy. His detachment had a lot to do with getting booted in '92. A review of the stock market back in '90 - '91 reveals that Big Oil shot up and helped a lot of folks in that business recover from the very hard times they went through in the late '80's. Though I was a conservative and a combat veteran, I campaigned for Bill Clinton in '92 as I was so disgusted with Bush the Elder. Still am. God save us from another Bush.
Most of us know in our heart of hearts that our troops are in Iraq and Afghanistan because of the continued grip the Mideast has on Western economies. In World War II, the U.S. national speed limit was 35 mph and gasoline was rationed with coupons. This was done to make sure the military had plenty of fuel. If some shared sacrifice was called for now, I think most Americans would grumble, but go along with it for the sake of untangling from the Iraq and Afghan Wars. How about bringing back the 55 mph speed limit of the '70's and '80's? What about a tax based on the weight of a vehicle? If we cut back on petroleum use, we help our independence and the environment at the same time. Now that's what I call "conserve-atism".
If you want to see what needs to be done about our dependence on petroleum, just look for the occasional Charles Krauthammer piece on it. He makes the same recommendations about every 5 years, the centerpiece of which is a flexible tax on gasoline that seeks to wean us off cheap oil while keeping the price of gasoline fairly steady.
In principio erat Verbum.
Automatic transmissions can be put into Neutral with a small move of the shifter, even while accelerating. This would have the same effect as pressing a clutch in a manual.
http://www.mhall119.com
Just like clockwork, there's another article on slashdot containing 'if they can get to market, solar panel prices could plummet!', which is nothing more than disingenuous wharrgarble. I see these articles every 2-3 months, and it's still Way Too Friggin' Expensive to pick up solar panels at my local store.
Call me when a 15 amp @ 14.1v isn't $1000 or higher, and we'll talk.
From Nanosolar's website, it sounds like they've been shipping panels commercially for the last two years, and that they have panel assemblies in both the US and Germany...
Yes, from Nanosolar's web site, it sounds that way. But as of 2009, "not one Solarply cell has been held yet in the hands of a consumer". There are no reports of actual Nanosolar installations. Supposedly they're building big solar panel installations for utility companies. So where are the announcements from those utility companies? Where are the regulatory filings, the planning documents, and the Google Earth pictures? Installing a big solar farm leaves a public record.