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Caltech Makes Flexible, 86% Efficient Solar Arrays

kdawson posted more than 4 years ago | from the bend-me-shape-me dept.

Earth 439

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.

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439 comments

First post (-1, Redundant)

Anonymous Coward | more than 4 years ago | (#31312588)

first

hmmmm (-1, Redundant)

Anonymous Coward | more than 4 years ago | (#31312590)

1st post

Wow. (-1, Redundant)

Anonymous Coward | more than 4 years ago | (#31312592)

Holy shit.

It's plastic ! (1, Interesting)

Taco Cowboy (5327) | more than 4 years ago | (#31312838)

How durable can this device be? It's made up of 98% plastic.

Re:It's plastic ! (2, Insightful)

Kryptonian Jor-El (970056) | more than 4 years ago | (#31312940)

I've never had problems with soda bottles...and thats 100% plastic

Re:It's plastic ! (4, Insightful)

MaskedSlacker (911878) | more than 4 years ago | (#31312990)

You've never left them out in direct sun for ten to twenty years then.

Re:It's plastic ! (3, Insightful)

Entropius (188861) | more than 4 years ago | (#31313006)

There's plastic, and then there's plastic. Some modern plastics are quite durable.

Re:It's plastic ! (0)

Anonymous Coward | more than 4 years ago | (#31313008)

As durable as many of the copters flying out there which are made with plastics
g

I think its entirely reasonable to say... (5, Insightful)

Serilleous (1400333) | more than 4 years ago | (#31312612)

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.

Re:I think its entirely reasonable to say... (5, Interesting)

camperslo (704715) | more than 4 years ago | (#31312712)

It sounds like the summary here is overstating the efficiency a bit. The numbers are for the absorption efficiency, not the overall conversion efficiency.

'The light-trapping limit of a material refers to how much sunlight it is able to absorb. The silicon-wire arrays absorb up to 96 percent of incident sunlight at a single wavelength and 85 percent of total collectible sunlight. "We've surpassed previous optical microstructures developed to trap light,"
.
.
The silicon wire arrays created by Atwater and his colleagues are able to convert between 90 and 100 percent of the photons they absorb into electrons--in technical terms, the wires have a near-perfect internal quantum efficiency. "High absorption plus good conversion makes for a high-quality solar cell," says Atwater. "It's an important advance."'

It looks like the overall efficiency is still very very high while using minimal resources. This is exactly the kind of innovation the U.S. needs for carbon-friendly jobs.
 

Re:I think its entirely reasonable to say... (3, Funny)

Anonymous Coward | more than 4 years ago | (#31312758)

This is exactly the kind of innovation the U.S. needs for carbon-friendly jobs.

Carbon friendly?! Dude, they are planning to reduce the amount of carbon being released. That's like calling Auschwitz "Jew friendly."

Re:I think its entirely reasonable to say... (0, Troll)

M8e (1008767) | more than 4 years ago | (#31312822)

This is exactly the kind of innovation the U.S. needs for carbon-friendly jobs.

Carbon friendly?! Dude, they are planning to reduce the amount of carbon being burned.

I don't think it's jew-friendly to burn jews.

Re:I think its entirely reasonable to say... (5, Funny)

Anonymous Coward | more than 4 years ago | (#31312866)

Actually it's spot-on. See, carbon-friendly means not turning the carbon into carbon dioxide. That is, it means not gassing the carbon. I think you would call not gassing Jews Jew-friendly.

Re:I think its entirely reasonable to say... (1)

zMaile (1421715) | more than 4 years ago | (#31313026)

I'm not 100% sure, but if 78% of electrons generate electricity, isn't there still wasted energy before it actually gets to the useful energy stage? i.e. energy in a single visible photon (~700nm if i recall) is significantly higher than the energy required to jump an electron up a state, and that difference in energy is turned into heat. this would have the effect of reducing the overall efficiency to 15% or something that is much lower. Is this true, or am i remembering bits and peices that are all wrong?

Re:I think its entirely reasonable to say... (4, Insightful)

polar red (215081) | more than 4 years ago | (#31312730)

I think that even if they only last 10 years at the same price per surface-unit, they'll still be more economically viable, because payback-time gets a lot better.

Plastic? 10 years under the sun? (0)

Taco Cowboy (5327) | more than 4 years ago | (#31312952)

When was the last time you find any plastic that can last 10 years under the sun?

Re:Plastic? 10 years under the sun? (4, Interesting)

Khyber (864651) | more than 4 years ago | (#31312964)

Saturn vehicles. Body panels are solid plastic, and I know Saturn has been around since the 90s.

Re:Plastic? 10 years under the sun? (3, Funny)

MaskedSlacker (911878) | more than 4 years ago | (#31312994)

Yeah, but it has to function after ten years too.

Re:Plastic? 10 years under the sun? (3, Interesting)

Entropius (188861) | more than 4 years ago | (#31313000)

Seconded. I sold a '94 Saturn last year that had been parked in the Arizona sun for many years. (Got rid of it due to multiple electronics failures and an engine oil leak that'd not be worth it to fix). Survived the sunlight just fine.

And the plastic body panels were GREAT. Lightweight and dent-proof.

Re:Plastic? 10 years under the sun? (4, Funny)

Snarf You (1285360) | more than 4 years ago | (#31313118)

'94 Saturn ... parked in the Arizona sun for many years ... multiple electronics failures ... engine oil leak

Survived the sunlight just fine

It sure sounds it.

*ducks*

Re:I think its entirely reasonable to say... (1)

MattskEE (925706) | more than 4 years ago | (#31312740)

I'd also be very interested to know whether this can be mass produced, and for how much money. They say they are currently working on cells one square centimeter in size.

They're currently working on scaling it up, but arranging these nanowires in a large array, making the electrical connections, and filling with the polymer and scatterers sounds like it will be hard to mass-produce, even if the materials cost is not as high.

Still, good for them.

Better Article... (5, Informative)

benjamindees (441808) | more than 4 years ago | (#31312800)

http://www.rsc.org/chemistryworld/News/2010/February/14021001.asp [rsc.org]

'We have shown the optical absorption efficiency and charge carrier collection efficiency of a silicon wire array cell is comparable to a conventional silicon cell, but a wire array cell uses up to 100 times less silicon due to enhanced light-trapping effects,' says Atwater. Significantly, the wire arrays absorb infrared light more efficiently that conventional silicon surfaces, further improving the performance of the new device.

So the gist is that it's more efficient because it converts infrared, uses some type of clear polymer with alumina "reflector particles" in place of 99% of the expensive (doped) silicon, and is flexible and therefore easier to manufacture.

Re:Better Article... (0)

Anonymous Coward | more than 4 years ago | (#31312890)

despite common assumptions, silicon is not all that expensive considering how ridiculously abundant it is. it's definitely not the most expensive part of a solar cell. moreover, the claims that this is flexible and therefore cheaper to manufacture in a roll-to-roll process is thrown around a lot, yet there's no proof that this is cheaper. the infrastructure for wafer growth is there, but not at all for any new process. lastly, as good as their cm-square cell may be (which is far from clear from the article: they say they need to raise open circuit voltage which means it may not be converting energy as efficiently as one would want) when scaled, yield and possibly increased complexity will certainly not make anything cheaper.

it's always good that people are working on new means of producing energy, but let's not fall for the "they did it in the lab, the world is saved!" type thinking..

Re:I think its entirely reasonable to say... (5, Informative)

vipw (228) | more than 4 years ago | (#31312864)

The original article is poorly written. MIT's Technology Review has an article that includes information about efficiency of generating electricity, and it says 15%-20%. http://www.technologyreview.com/energy/24665/?a=f [technologyreview.com]

So the story is really that there might be a way to make cheaper, flexible solar panels by mixing silicon and polymers.

Re:I think its entirely reasonable to say... (5, Interesting)

Anonymous Coward | more than 4 years ago | (#31312946)

I saw this posted by grobbo at engadget: http://www.engadget.com/2010/02/28/caltech-gurus-whip-up-highly-efficient-low-cost-flexible-solar/#comments [engadget.com]

Turns out the only benefits to this are the flexibility and low cost (which are good, sure, but not that exciting).
According to their letter to nature.com this "also may offer increased photovoltaic efficiency", _may_ suggests to me there probably isn't any significant improvement.

For anyone wondering why high absorption and a high QE don't necessarily result in high energy conversion (like I was a few hours ago) it's because 30% of the photons have insufficient energy to free an electron in silicon, and most of the rest of the photons have more energy than needed to free an electron, so any excess energy beyond that required to free a single electron is wasted as heat.

Re:I think its entirely reasonable to say... (0)

Anonymous Coward | more than 4 years ago | (#31312874)

Don't worry, once your electric company knows you installed them, they'll add an extra fee onto your bill... for not using more of their electricity...

Believe it.

Re:I think its entirely reasonable to say... (1)

MaskedSlacker (911878) | more than 4 years ago | (#31313004)

Fortunately electric companies are better regulated than the credit card companies. By which of course I mean, regulated at all.

Re:I think its entirely reasonable to say... (0, Offtopic)

ShakaUVM (157947) | more than 4 years ago | (#31312988)

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.

Currently, without subsidies, Solar PV is roughly 20x-100x more expensive than coal or nuclear power. If it is indeed twice as efficient and costs 10% of the current costs to fabricate, then solar might finally become cost competitive.

If I was Obama, I'd toss a billion or so at this scientist and see if he couldn't get mass production of it up and running.

I mean, as long as we're spending billionS keeping teachers temporarily employed (because their states can't afford them right now), right?

Re:I think its entirely reasonable to say... (0, Troll)

Anonymous Coward | more than 4 years ago | (#31313046)

I think it'd be perfectly justifiable to fire all the teachers to fund this. Even if it all ended up being hype.

Efficiency (0)

Anonymous Coward | more than 4 years ago | (#31312616)

This sounds like an incredible breakthrough. I thought that the very best solar cells were at about 40% efficiency. http://www.scientificamerican.com/blog/post.cfm?id=new-solar-cell-efficiency-record-se-2009-08-27 [scientificamerican.com]

This article describes ~80%. What am I missing? I can't understand why the article is written as it is if these are really the highest efficiency solar cells ever created.

Re:Efficiency (3, Informative)

MaskedSlacker (911878) | more than 4 years ago | (#31312896)

Collection efficiency (which is what TFA is claiming to be 86%) vs. conversion efficiency (that 40% number you remember) is what you're missing, but from other articles on the technology it appears that the conversion efficiency for these cells should be higher than existing designs:

The silicon wire arrays created by Atwater and his colleagues are able to convert between 90 and 100 percent of the photons they absorb into electrons--in technical terms, the wires have a near-perfect internal quantum efficiency. "High absorption plus good conversion makes for a high-quality solar cell," says Atwater. "It's an important advance."'

Which could give them ~78% conversion efficiency, still nearly double over the best cells currently.

Absorbed not necessarily equal to electricity (4, Insightful)

Reverse Gear (891207) | more than 4 years ago | (#31312618)

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.

Re:Absorbed not necessarily equal to electricity (5, Insightful)

Anonymous Coward | more than 4 years ago | (#31312658)

If light is absorbed but not converted to electricity, isn't the panel going to get hot?

Re:Absorbed not necessarily equal to electricity (5, Funny)

someone1234 (830754) | more than 4 years ago | (#31312804)

Well, getting hot water out of it is a feature, not a bug.

Re:Absorbed not necessarily equal to electricity (1)

MaskedSlacker (911878) | more than 4 years ago | (#31312912)

Hot air. Hot air. Dammit, you missed the obvious joke by 998.7 kg/m^3.

Re:Absorbed not necessarily equal to electricity (4, Informative)

profplump (309017) | more than 4 years ago | (#31312986)

Yes, just like any other dark panel you leave in the sun. Except not as hot, because some of the energy is being exported as electricity. So unless they're flammable at really low temperature we'll probably be okay.

Re:Absorbed not necessarily equal to electricity (4, Informative)

Random Data (538955) | more than 4 years ago | (#31312672)

There was a bit further down that said conversion to electricity was 90-100% of absorption. That means a worst case efficiency of 77% of incident sunlight, which is still a staggering improvement over standard cells. I for one welcome our new silicon-wire overlords.

Re:Absorbed not necessarily equal to electricity (3, Insightful)

amiga3D (567632) | more than 4 years ago | (#31312678)

The problem with current panels isn't the efficiency. More efficiency is welcome but the real problem with solar panels is the cost. It takes too many years to recoup the very heavy initial investment. If the price can be made such that the panels pay for themselves with 2 or 3 years then they make solar power a real alternative to the grid.

Re:Absorbed not necessarily equal to electricity (5, Insightful)

Entropius (188861) | more than 4 years ago | (#31312724)

I don't understand why the break-even time on solar has to be on the order of a handful of years for it to be economically feasible.

The break-even time for nuclear is over a decade, and it's pretty long for hydro projects too. So why do we insist that solar has to turn a profit Real Quick Now?

Re:Absorbed not necessarily equal to electricity (5, Insightful)

Calinous (985536) | more than 4 years ago | (#31312812)

For appeal to common users, and also for appeal to producers.
      Now, solar is limited by two big things:
1. total cost (panels are expensive, so few people buy them, so few people produce them, so they are more expensive than it could be)
2. the Return on Investment is low (extreme cases - 10 years, but typically more than 20).

      If a cheap production method can be devised, this will open the market to many buyers (many people don't even consider buying a $25,000 solar panel system, but will buy in a heart beat a $2,500 solar panel system).
      Also, a cheap production method will allow (hopefully) a quick panel production ramp up)

Re:Absorbed not necessarily equal to electricity (1)

MaskedSlacker (911878) | more than 4 years ago | (#31312930)

None of what you just said contributed to the conversation in anyway. All you did was repeat the GP's statement of the problem in more detail.

His point was that nuclear and hydro (and I'll add coal to that list too) power plants take longer to recoup their initial investment, so there's no reason for this to be a problem for solar power other than stupid reporters repeating the myth that it takes to long to pay for itself, and thus people actually believe it.

Re:Absorbed not necessarily equal to electricity (0)

Anonymous Coward | more than 4 years ago | (#31312820)

Because one of the primary benefits of solar is how easy it is to implement in small installations, such as for a single household. And the economics of those installations are very different from the economics of traditional power plants.

Re:Absorbed not necessarily equal to electricity (1)

Entropius (188861) | more than 4 years ago | (#31312966)

I buy things for my household that I expect to keep for many years, like cars and major appliances. Why can't solar power be the same way?

If a solar installation can repay itself in 15 years, then either buy one or borrow money and then buy one, just like you do with any other big residential purchase.

Re:Absorbed not necessarily equal to electricity (1)

Eivind (15695) | more than 4 years ago | (#31312834)

It doesn't have to be 2-3 years, that's nuts (if it was, people would build solar until the price of energy dropped enough that the payback-time rose)

But it -does- need to be significantly less than the expected lifetime of the panels. Current ones tend to be estimated at 20 years, though local conditions influence it a lot.

With a payback of 10 years, it'd probably be interesting.

At the moment though, you typically get around 2% of the purchase-and-installation cost in payback a year, so you'd recoup in 50 years... except they're dead long before and 2% is much too low a profit anyway (you'll get more by putting the money in the bank)

Re:Absorbed not necessarily equal to electricity (2, Insightful)

ZzzzSleep (606571) | more than 4 years ago | (#31312840)

I think it's because solar can be done at a household level, which nuclear and hydro can't. As the break-even time goes down, more homeowners are able to say, "I'll install some of those solar panels", and have the cash back relatively quickly.

Re:Absorbed not necessarily equal to electricity (4, Insightful)

Kryptonian Jor-El (970056) | more than 4 years ago | (#31312854)

Because I don't pay for the nuclear plant or the hydro dam. However, getting the money together to buy and install the solar panels is all on me, the homeowner

Re:Absorbed not necessarily equal to electricity (4, Interesting)

MaskedSlacker (911878) | more than 4 years ago | (#31312948)

Because I don't pay for the nuclear plant or the hydro dam

Yes you do (if you use power from one).

However, getting the money together to buy and install the solar panels is all on me, the homeowner

No it's not. I see/hear ads from solar power rental places all the time (on local media no less, but then again it is Los Angeles). They will do the full install at no upfront, then charge you amortized payments--if the payments are less than what you save on electricity (which their ads claim will usually be the case, for what that's worth, I have no idea if that part's true) then they pay for themselves on day one.

Re:Absorbed not necessarily equal to electricity (1)

TRRosen (720617) | more than 4 years ago | (#31312892)

Because most current cells break down and become less efficient over time. eg the don't last forever!

Re:Absorbed not necessarily equal to electricity (0)

Anonymous Coward | more than 4 years ago | (#31313084)

eg the don't last forever!

Do you have any other examples?

Re:Absorbed not necessarily equal to electricity (1)

TapeCutter (624760) | more than 4 years ago | (#31312974)

"The break-even time for nuclear is over a decade, and it's pretty long for hydro projects too. So why do we insist that solar has to turn a profit Real Quick Now?

It's important if you want Joe Home-owner to shell out the initial investment, not so much if it's a corporation setting up a plant to generate hundereds of megawatts. That being said TFA claims this design uses 1/50th the amount of silicon crystal which is the expensive part in existing cells. Not only would it be a lot cheaper to make the new cells but the new cells nearly doubles the efficientcy of existing ones, meaning you only need to buy half as many cells.

If they can get the up front cost to power a house by solar down to 1/4 - 1/3 of the current price then all of a sudden Joe Home-owner is going to become very interested.

Re:Absorbed not necessarily equal to electricity (1)

barv (1382797) | more than 4 years ago | (#31313044)

there are two possible reasons why a 10 year payback period might be too short.
1) Solar cells cost energy to produce. We would like to get at least as much energy back as we put in.
2) Solar cells cost money to produce. When the total life energy (KWH) produced is divided into the total cost, we arrive at the cost per KWH. We would like that cost to be lower than the local power utility supply cost.

Re:Absorbed not necessarily equal to electricity (1)

mweather (1089505) | more than 4 years ago | (#31313068)

The break-even time for nuclear is over a decade,

And it gets worse with every plant we build.

Re:Absorbed not necessarily equal to electricity (1)

Coriolis (110923) | more than 4 years ago | (#31312908)

No, the problem with the current panels is the cost per Kilowatt Hour. If the panels can produce more for the same price, then the payback period is shorter.

Re:Absorbed not necessarily equal to electricity (1)

aka1nas (607950) | more than 4 years ago | (#31312916)

The problem with current panels isn't the efficiency. More efficiency is welcome but the real problem with solar panels is the cost. It takes too many years to recoup the very heavy initial investment. If the price can be made such that the panels pay for themselves with 2 or 3 years then they make solar power a real alternative to the grid.

We have relatively cheap panels as well, but their problem is low efficiency. The current higher efficiency panels usually need exotic materials and manufacturing processes. If this new tech can replace both groups of cells, then it would be a huge boon.

Re:Absorbed not necessarily equal to electricity (1)

oddaddresstrap (702574) | more than 4 years ago | (#31312682)

FTFA: "The silicon wire arrays ... are able to convert between 90 and 100 percent of the photons they absorb into electrons--in technical terms, the wires have a near-perfect internal quantum efficiency".

Re:Absorbed not necessarily equal to electricity (1)

worip (1463581) | more than 4 years ago | (#31312692)

It sounds as if the cells has a high quantum efficiency as well. From the article:

The silicon wire arrays created by Atwater and his colleagues are able to convert between 90 and 100 percent of the photons they absorb into electrons—in technical terms, the wires have a near-perfect internal quantum efficiency. "High absorption plus good conversion makes for a high-quality solar cell," says Atwater. "It's an important advance."

Almost too good to be true, but if it is (and it scales well), invest in some desert land area, because solar has just become viable.

Re:Absorbed not necessarily equal to electricity (1)

maxfresh (1435479) | more than 4 years ago | (#31312762)

The article adresses that issue up front, stating explicitly that 90-100% of the absorbed light is converted into electricity. From the article:

Atwater and his colleagues--including Nathan Lewis, the George L. Argyros Professor and professor of chemistry at Caltech, and graduate student Michael Kelzenberg--assessed the performance of these arrays in a paper appearing in the February 14 advance online edition of the journal Nature Materials.

Atwater notes that the solar cells' enhanced absorption is "useful absorption.".

"Many materials can absorb light quite well but not generate electricity--like, for instance, black paint," he explains. "What's most important in a solar cell is whether that absorption leads to the creation of charge carriers.".

The silicon wire arrays created by Atwater and his colleagues are able to convert between 90 and 100 percent of the photons they absorb into electrons--in technical terms, the wires have a near-perfect internal quantum efficiency. "High absorption plus good conversion makes for a high-quality solar cell," says Atwater. "It's an important advance.".

The key to the success of these solar cells is their silicon wires, each of which, says Atwater, "is independently a high-efficiency, high-quality solar cell." When brought together in an array, however, they're even more effective, because they interact to increase the cell's ability to absorb light..

So, assuming their worst case figure of 90% efficiency, and 85% absorption, the overall light to electricity conversion efficiency would be ~76.5%

If this technology scales, and can be manufactured economically, it will be a tremendous breakthrough, which could deliver significant and long lasting benefits for the entire planet.

Re:Absorbed not necessarily equal to electricity (1)

TRRosen (720617) | more than 4 years ago | (#31312882)

The article states a quantum efficiency of %90-%100. That is the rate of photons converted to electrons. So you have a high rate of absorption and a high rate of conversion. 77% total efficiently (see below) of course they have only made them 1cm square so far.

Re:Absorbed not necessarily equal to electricity (1)

saodl (750228) | more than 4 years ago | (#31312884)

It's a lot better than that; in fact it sounds like somewhere between 77.4% and 85% to me. They say "up to", so maybe it's less. Lets just call it upwards of 60% or 70%. For a lower cost. That's huge enough that I don't want to trust it, but I sure hope it pans out.

The article says:

The silicon-wire arrays absorb up to 96 percent of incident sunlight at a single wavelength and 85 percent of total collectible sunlight.

and

The silicon wire arrays created by Atwater and his colleagues are able to convert between 90 and 100 percent of the photons they absorb into electrons—in technical terms, the wires have a near-perfect internal quantum efficiency. "High absorption plus good conversion makes for a high-quality solar cell," says Atwater. "It's an important advance."

Meh (5, Funny)

zmollusc (763634) | more than 4 years ago | (#31312628)

All these idiots working on solar panels when what is really needed is overcast panels to get power from gloomy days when you use more light bulbs.

Re:Meh (4, Insightful)

Entropius (188861) | more than 4 years ago | (#31312982)

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?

Re:Meh (2, Funny)

Jimbookis (517778) | more than 4 years ago | (#31313014)

Meanwhile, in Australia where there is more sun than you can poke a solar panel at, with regards to pushing solar and renewable, is literally standing around with it's dick in both hands.

Re:Meh (1, Insightful)

Anonymous Coward | more than 4 years ago | (#31313034)

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.

Re:Meh (1)

TapeCutter (624760) | more than 4 years ago | (#31313106)

"All these idiots working on solar panels when what is really needed is overcast panels to get power from gloomy days when you use more light bulbs."

Yeah, but try telling that to those silly Germans [wikipedia.org] .

NOT incandescent light! (4, Informative)

scdeimos (632778) | more than 4 years ago | (#31312640)

It's not incandescent light, it's incident light. sigh.

Re:NOT incandescent light! (1)

Entropius (188861) | more than 4 years ago | (#31312734)

I was about to comment on the absurdity of "single-frequency incident light" until I saw that TFA had it right. I figure this can slip as a typo or brain-o rather than something out of ignorance.

Re:NOT incandescent light! (0)

Anonymous Coward | more than 4 years ago | (#31312782)

Which is especially ironic since sunlight is incandescent.

Re:NOT incandescent light! (1)

TandooriC (1525601) | more than 4 years ago | (#31312858)

My gawds, I thought I saw indecent light somewhere there. Sigh.

Re:NOT incandescent light! (0)

Anonymous Coward | more than 4 years ago | (#31312906)

Ahh, I was hoping we'd power the future using lightbulbs

Will they float? (4, Funny)

MillionthMonkey (240664) | more than 4 years ago | (#31312644)

If we set up solar devices so that they can float in water and function as an interconnected grid, we could drape a network of them over the Pacific Garbage Patch so no one would notice it.

Re:Will they float? (0)

Anonymous Coward | more than 4 years ago | (#31312796)

If we set up solar devices so that they can float in water and function as an interconnected grid, we could drape a network of them over the Pacific Garbage Patch so no one would notice it.

It's actually a government conspiracy to turn the Pacific into a giant polymer solar cell to power their underwater base. Either that or it's the plot of the next X-Files movie.

Is that the right question? (1)

jonaskoelker (922170) | more than 4 years ago | (#31312978)

Will they float?

Maybe, but what I really want to know: will it blend?

Re:Will they float? (1)

nacturation (646836) | more than 4 years ago | (#31313020)

But then an oil tanker would accidentally stray off course and cut the power cable with its propellers.

In requires polymer to make... (3, Interesting)

assemblerex (1275164) | more than 4 years ago | (#31312646)

so it is still tied to oil. Becoming cheap and widely popular may do more harm than good I fear.

Re:In requires polymer to make... (1)

Serilleous (1400333) | more than 4 years ago | (#31312684)

It is tied to oil, but methinks that this probably produces a much better energy per (black stuff consumed / pollutants produced) than most available technology. Certainly not a solution, but definitely an improvement on the current situation.

Re:In requires polymer to make... (0)

Anonymous Coward | more than 4 years ago | (#31312710)

Who cares? If we get cheap solar technology we'll have enough energy to make as much oil as we want from carbon dioxide and water.

Re:In requires polymer to make... (5, Insightful)

Anonymous Coward | more than 4 years ago | (#31312720)

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.

Re:In requires polymer to make... (0)

Anonymous Coward | more than 4 years ago | (#31312786)

Weeeelll, methinks that with the sheer volume of plastic waste produced daily, a few thousand square kilometers won't be a huge deal.

Re:In requires polymer to make... (2, Insightful)

pushing-robot (1037830) | more than 4 years ago | (#31312836)

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.

Re:In requires polymer to make... (1)

MaskedSlacker (911878) | more than 4 years ago | (#31312976)

Even when there's no life on Earth we'll be able to produce all the polymers we'll need.

Re:In requires polymer to make... (1)

TRRosen (720617) | more than 4 years ago | (#31312920)

you don't need oil to make polymers (its a lot easier though) hell you don't even need oil to make oil.

Re:In requires polymer to make... (2, Insightful)

MaskedSlacker (911878) | more than 4 years ago | (#31312972)

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).

Re:In requires polymer to make... (0)

Anonymous Coward | more than 4 years ago | (#31313064)

That's what they want to make you believe. The whole green-house topic is a big conspiracy.

Natural resources are limited. However, conveying reduced consumption of the public just due to the limited nature is doomed to failure. Therefore, a plan was set up to scare people away from using too much.

Quite funny that the article mentions positively how few silicon it's using. Last time I checked it was still in quite good supply - like sand on a beach.

Re:In requires polymer to make... (2, Informative)

MaskedSlacker (911878) | more than 4 years ago | (#31313110)

Last time I checked you're a blithering idiot who talks out of his ass.

Does silicon grow on a beach? In a manner of speaking...

However, the factories that process raw silica into high grade silicon for semi-conductor production are in short supply, and this has driven up the price of silicon. Silica is cheap, and every where. Silicon is manufactured, and currently not cheap (enough for widespread solar panels).

Re:In requires polymer to make... (1)

TapeCutter (624760) | more than 4 years ago | (#31313040)

"so it is still tied to oil. Becoming cheap and widely popular may do more harm than good I fear."

I for one hope this does maximum harm to the wallets of coal luddites such a Senator Inhofe and his corporate pay-masters.

And these are available in stores? (0)

Anonymous Coward | more than 4 years ago | (#31312660)

What's that? A concept in search of venture capital? Oh.

Massive typo in summary. (4, Informative)

talcite (1258586) | more than 4 years ago | (#31312702)

The solar cells absorb 96% of incident light, not incandescent light.
From TFA:

The silicon-wire arrays absorb up to 96 percent of incident sunlight at a single wavelength and 85 percent of total collectible sunlight.

85% of sunlight (0)

Anonymous Coward | more than 4 years ago | (#31312770)

I know this is being picky but the article says 85% of sunlight not 86% as in the summary.

So what do I win?

So when can I buy those? (1)

Kokuyo (549451) | more than 4 years ago | (#31312778)

That's all I really want to know. If I can put them on my roof for a reasonable price, I'll be one happy wanker, but lab situations just don't necessarily translate so well into real life.

Not having read the article I don't know whether it was mentioned.

Assuiming that production of these is not too difficult, this seems like a very good way to produce power for you and at least one neighbour just by tiling one roof (I'm pulling the figures for that calculation out of my ass, so if you want to comment on that don't go physics nazi on my ass, please). Imagine only one third of the homeowners doing this kind of thing, we could probably have ourselves a very decentralized power grid in no time. Especially you in the US should welcome that, seeing as your grid has a lot of problems with delivery today.

Anyway, I'm really hoping this turns out to be something of real value. It makes me all giddy with anticipation.

Re:So when can I buy those? (1)

Hairy1 (180056) | more than 4 years ago | (#31313018)

Way to early to be talking mass production. But very promising science. If they are right they will be very rich little scientists.

Re:So when can I buy those? (1)

shinzawai (964083) | more than 4 years ago | (#31313072)

With the money you save, perhaps you can pay someone to wank you off! Happy times indeed! (No, I'm not putting my hand up for that job)

So.... (0)

Anonymous Coward | more than 4 years ago | (#31312852)

Cost efficient solar energy is only now 20 years away!! Hooray!

It's a lie! (0)

dvh.tosomja (1235032) | more than 4 years ago | (#31312942)

Efficiency of solar panel is and always was 14 to 17%.
Every 3 months or so there is a slashdot article claiming breakthrough in efficiency.
Please stop spreading this meme.
Thank you.

This is way over-hyped (4, Informative)

rkodama (716651) | more than 4 years ago | (#31312954)

This is interesting work, but it is in a very immature stage of development. They seem to be no where near demonstrating a practical solar cell, and speculated conversion efficiency numbers like 86% are laughable. One of the fundamental limitations of a cell based on Si wires is that the higher a photon's energy is over the bandgap of Si, the more energy is lost as heat. I believe the theoretical maximum conversion efficiency for a Si solar cell is around 30%, and commercially viable cells are limited to around 20% because of practical issues in creating solid state cells such as making electrical contacts to the device, the high cost of making higher efficency (20+%) Si cells. This work doesn't begin to address such issues. I think it is unfortunate that over-hype like this can take luster off of progress in photovoltaics that seems less spectacular but is much closer to practical realization.

Re:This is way over-hyped (1)

thephydes (727739) | more than 4 years ago | (#31313062)

and over-hyping is unusual on slashdot? You must be new here.

red light (3, Interesting)

timmarhy (659436) | more than 4 years ago | (#31313074)

firstly, kdawson your a tard, they aren't 86% efficent at converting light into electricity, merely at absorbing light. the 2nd warning bell for me is this - "The next steps, Atwater says, are to increase the operating voltage " - this sounds to me like they can't produce any meaningful voltages out of these, which is the exact same fail as every other flexible solar panel ever touted. infact they carely avoid talking about it's electrical output at all in TFA.

i'd love cheap energy from the sun, but this won't be it.

I want to believe it, but.. (1)

nightfire-unique (253895) | more than 4 years ago | (#31313078)

If this is true and accurate, this may be one of the biggest energy science advances since nuclear fission. A >75% efficient solar cell that can be manufactured for, say, $100/kW?

I want to believe this is true, and commercialization is just around the corner... because if it is, this could solve our coal-power CO2 emissions overnight.

A 3x4 meter panel of this stuff would run an average North-American home year-round (heating, A/C, hot water), and it sounds like it could cost $1-2k. Even with $5k worth of support hardware (batteries, inverter/charge controller, transfers) this system would pay for itself in under 5 years.

Predicted photovoltaic efficiency only 14.5% (4, Informative)

Animats (122034) | more than 4 years ago | (#31313088)

Here's the actual scientific paper, "Predicted Efficiency of Si Wire Array Solar Cells". [caltech.edu] That's by the same authors mentioned in the press release. While the thing does trap most of the light hitting it, only a fraction of the energy in that light is converted to electricity. In fact, this thing is currently less efficient than the better commercial solar cells.

From the paper: ... simulated photovoltaic efficency of 14.5%. ... Conclusion: ... "Si wire array solar cells have the potential to reach efficiencies competitive with traditional Si crystalline solar cells."

So, an interesting development, but no big breakthrough. There's a claim that it might be a cheaper way to make solar cells, but everybody who comes up with a new design makes that claim. (Nanosolar comes to mind; their technology is supposed to be cheaper, but so far they've spent half a billion dollars and apparently have only produced sample panels.)

Don't confuse internal quantum yield with external (0)

Anonymous Coward | more than 4 years ago | (#31313108)

The press release specifically says the 90% or so conversion is the internal quantum yield. That means for each for each photon absorbed, 90% of the energy is converted to work. However, this is still a single bandgap material (silicon) and the maximum theoretical external quantum yield for a single bandgap system is 33%. For the 1.12 eV bandgap of silicon, it is 28%. The advantage that Nate and Harry have here is the use of flexible Si based materials, that can use lower quality Si due to the short charge carrier diffusion lengths of the cylindrical system. This represents an inprovement where the cells can be deployed, ie where felxibility is important, and the chance to reduce the cost of the system through less expensive processes for Si manufacture. Now Nate's group is currently working on water splitting with these, using the high aspect ratios to use lower efficiency (and cost) catalysts, and Harry is making radial n-p++ junctions out of these. Neither system is going to rival the external quantum yields of the flat panel Si systems, much less the current photovoltaic champions, the metamorphic triple junctions from Spectrolab, which currently sits at 42.7%, but there is room for cost improvement with this system.

nice try blanco nino (5, Insightful)

l3iggs (1108141) | more than 4 years ago | (#31313124)

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.

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