Caltech gurus whip up highly efficient, low cost flexible solar cell
By Darren Murph 
posted February 28th 2010 1:11AM
posted February 28th 2010 1:11AM
Solar cells are cute and all, but let's be real -- these things are far too inefficient for mainstream use. Scientists at the California Institute of Technology are working hard to remedy that very issue, and they've recently concocted a "new type of flexible solar cell that enhances the absorption of sunlight and efficiently converts its photons into electrons." The solution relies on arrays of long, thin silicon wires embedded onto a polymer substrate, which uses just a fraction of the expensive semiconductor materials required by conventional solar cells. According to professor Harry Atwater, these cells have "surpassed the conventional light-trapping limit for absorbing materials" for the first time, and we're told that the arrays can convert between 90 and 100 percent of the photons they absorb into electrons, and yes, that does mean that they have a near-perfect internal quantum efficiency. Hit the source link for all the technobabble, and cross your fingers for this stuff to get the honored approval of the Governator.
How would you compare this to the Bloom Box?
@n0ne
Well the Bloombox requires fuel, and emits CO2 at 0.8 lb/kwh, so I wouldn't even bother comparing the two.
@n0ne Does this mean it doesn't heat up at all even in direct sunlight?
@grobbo You might need the bloom box for the night or be prepared to bear the brunt of manufacturing some batteries !
@n0ne,
These new photovoltaic cells will produce approximately 4 times as much power as existing cells. For the same surface area, a Bloom Box will toast these solar cells. These solar cells may not even power your refrigerator if it occupies the same footprint as a Bloom Box, whereas the Bloom Box will light-up your entire neighborhood! But consider this, each Bloom Box cost $700,000. The company hopes to release models at a cost of $3,000 within 5 to 10 years that will power a single American home. All they need is for the Obama Administration to step in and make it happen in 3 years. Increase my tax by $10 if they do not have the money, I would gladly contribute to making it happen. Saving the money we give to OPEC and other nations to buy all that foreign oil will make every American richer. You could use the excess energy your Bloom Box will generate to power your future electric or hybrid car. You may even be able to sell the excess electricity back to the power company.
Now back to this invention; what this invention is good for is to make portable cell-phone solar chargers useful; the current generations of chargers are totally useless! You can also cover the roof of your house with these photovoltaic cells and they could be used to provide free energy to the Bloom Box which will then generate much more power (or electricity) than what it is receiving from the solar cell.
@Thinker
Thinker, you don't understand the Bloombox.
You feed in gas (natrual gas, biogas, whatever) and get electricity out.
One by-product is CO2 (8 lb/kwh)
You do not (and cannot) feed electricity in, and get (more!) electricity out.
@grobbo
Pshaw - you've obviously never heard of a little thing called the "Steorn Orbo".
@n0ne The Bloom box exists. This is merely technology. the 1cm cells they've made won't power much.
@grobbo you dont know how a fuel cell works, do you?
Fuel cells can work in reverse. Instead of passing in H + o to produce electricity you can pass in H20 + electricity to make hydrogen fuel. That can act as a storage for all this access electricity....you can pass that back in later and make it. this would be c02 free :)
@n0ne
This and the Bloom Box work in conjunction. The solar panels route their power to the Bloom Box's, which then turns it into electricity. One off the problems that solar has had is in storing power for when the sun is not shining. Using solar panels in conjunction with a Bloom Box would solve this problem and produce clean, local, and cheap power.
@grobbo
This and the Bloom Box work in conjunction. The solar panels route their power to the Bloom Box's, which then turns it into electricity. One off the problems that solar has had is in storing power for when the sun is not shining. Using solar panels in conjunction with a Bloom Box would solve this problem and produce clean, local, and cheap power.
@artemis360
sorry for double posting
@ipxnsv
I haven't said anything opposing this anyway, and no-one suggested it before you either, but do you know what is required to store Hydrogen? No household will be doing that.
@artemis360
No, you don't understand the Bloombox either.
Solar panels produce electricity. The Bloombox produces electricity (from gas). Solar panels cannot feed the Bloombox, and it would be absurd to feed in electricity to receive electricity!
For storage, you can use these other things, called "batteries" .
@grobbo,
I am correct, the Bloom Box is planned to use solar - by the time they release units available for inexpensive home deployment.
Read this extract from Bloom Energy's site:
http://www.bloomenergy.com/benefits/more-benefits-and-applications/
"Coupled with intermittent renewable resources like solar or wind, Bloom’s future systems will produce and store hydrogen to enable a 24 hour renewable solution and provide a distributed hydrogen fueling infrastructure for hydrogen powered vehicles."
@Thinker
No, you are wrong.
Yes, you can run it in reverse to store energy in Hydrogen (although that is so impractical for a household that we aren't likely to see it) but you don't gain any energy from doing so. In fact you will lose energy, because the Bloombox cannot operate with 100% efficiency in either direction.
@grobbo,
Peace :)
@grobbo
The bloom box is essentially a cheap efficient battery and line conditioner. You certainly can power it with solar based electricity. You would want to also, because solar is too inconsistent to wire directly to it's application. Instead, you wire it to a battery system and in turn draw from that. The benefit is continuous power when the sun isn't around and the capacity for higher amperage draw downs than direct solar can generate.
Hard to believe the 90% yo 100% efficiency. We need to see the real product.
@mianmian
yeah id like to see the real prroduct im having a hard time figuring out what in deed this is
@mianmian
Well even if this hits 50%+ it would be great. And if they use less material that is expensive then we have a winner.
In 50 years we will ALL have a roof made out of Solarpanels.( Think about the ammount of energy we can create arround the globe ) And big international powerdistribution systems. And buffer systems. Then we don't need any other source of electricity. As we can generate SOOO much energy. We can have inefficient buffers( that last hundreds of years )... The inefficiency is not a factor anymore because energy will be very very cheap.
@mianmian NO. THESE CELLS WILL BE 15-20% EFFICIENT in finished product form according to MIT's reporting at techreview.com. I don't know how other sources flubbed this, but if a cell had on the order of 90% or greater actual total efficiency, no matter how much it cost, it would be earth shattering news. This is clearly not.
-
Of course, a truly cheap cell at 20% efficiency would be awesome. A lot of thin film cells are only like 10% or less and are still being commercialized. Right now only fairly expensive pure silicon based cells get up to 20% efficiency. Some super high tech multilayer cells can get over 30% but these are so expensive they're only used in spacecraft etc.
@mianmian: The silicon wires themselves may be highly efficeint, but the key measure is efficiency per unit of area, and as they say if you look into the PR, only 2% of the area is silicon. Although they say that they get a certain amount of unexpected benefit from interaction between the wires, this still doesn't equate to anything close to 90-100% overall efficiency. Of course they don't quote a figure for efficiency per unit area!
@mianmian They say 90-100 percent efficiency of the photons that get in, i'm sure it doesn't absorb 1/2 of the photons that it comes in contact with.
90 to 100% efficiency? Low cost?! Doesn't this SOLVE the energy crisis??!! Isn't this what we've been waiting for?? Seems waay too good to be true.
@B3astofthe3ast
Totally. Where do I buy the stock...?
@B3astofthe3ast
Absolutely, but there's probably a huge caveat that we're not aware of (maybe it relies on eating kittens to work?)
@B3astofthe3ast
85% absorption, so 77-85% total conversion, which is still amazing.
I hope we see this confirmed as the real deal somewhere reliable, soon.
@B3astofthe3ast Near perfect internal quantum efficiency says only that nearly every photon generates an electron. Solar cells with >100% efficiency are known (multiple carrier injection), but QE doesnt say anything about energy conversion. The ENERGY conversion efficiencies you usually hear about (which top out in the 35% range) expresses how much of the energy of each photon is converted to the electron. It's an important distinction
@RincewindWiz Yeah, but fortunately, only _ugly_ kittens.
@B3astofthe3ast
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.
@grobbo
Forgot to add, 85% is actually only 85% above band-gap.
Please tell me a california tech company has patented this technology already or i'm going to have a heart attack
90-100% out of what... 0.000001% of the suns light??
@KGB if we could harvest just .0001% of the sunlight that is bathing Earth then that would be enough to power all of humanity....
@scplayer4
So this is new tech kind of pointless then? Im honestly curious if this is just another vaporware.
@KGB Firstly this is not a 'ware', it is an invention.
Come out of your smart looking tech jargons, sometimes they make you look like a fool.
@sourav
You could have just given me an answer to my question instead being a internet lingo Nazi.
Mkay?
@scplayer4
Humanity does okay powering itself, sans politcal and distribution issues.
It's our -things- that are the power eating monsters
@Cy Starkman I understand where you're line of thought might come from, but humanity has some real trouble powering itself. 1.02 billion people worldwide can't get enough food to sustain themselves. That means 15.2% of all humans don't have there prime energy needs met.
Great, we can combine this with some other phantom battery enhancement and... I can't even be sarcastic, there have to be at least 2-3 articles a week about breakthroughs in green and battery technology, and I'm still waiting for one of them to come true!
@Valicore
Thats because every one is on the Green bandwagon and scamming the money out of Government by promising new Green tech that will do wonders in 10 years.
@Valicore
You can't be reading the same science sites I read then. Energy tech is a topic that interests me, and I've never seen an announcement like this before.
@KGB
Yes, all those evil, money-hungry scientists should be ashamed.
@grobbo
I should have said "many" people, as many people are desperate now days to make money any way possible in this economy.
Have you heard of the program called Drive 55? Where Government is telling us that driving at 55mph will save you tons of gas and will help us to stop being dependent on foreign oil. Thus many people use this BS scheme to promote it and make money from it in the process.
@KGB um so who makes money from driving slower? you do (the person who drives slower) because you use less fuel. the oil companies make less money (because you use less fuel) and the government makes less money (from sales tax on fuel). not quite sure where you're finding the conspiracy here.
as for PV solar, it can be a useful technology and if this advance lowers the cost of production then it probably also lowers the environmental damage of production too, which is a good thing (solar PV is already not bad on that score, but only because the panels last so long). Depending on the situation (ie somewhere reasonably sunny with suitable roof), solar PV is a useful energy component because it can be generated locally and it provides energy during the daytime, which is when highest energy demand is. A particularly obvious benefit is if electricity is used to run air conditioning; it's sunny, you need more air conditioning, you get more energy to help power it.
While it's environmentally efficient enough to be a benefit, unfortunately I don't think that yet applies financially - i.e. the payback time from investing in solar panels is way too high - so anything that significantly reduces the cost is a big help.
(I'm not sure solar pv is a good idea for large scale plants, I would have thought the solar concentrating plants are a better idea, but i don't know the details. But anyhow this might be good for local domestic/commercial usage.)
@whoever said we hear about loads of this type of advance but none of them ever happen - yeah we do, and yeah most of them turn out to be unworkable - but the ones which do work, you don't really hear about them because it just translates into general improvement. Like if in five years solar panels cost half as much as they do today and are slightly more efficient, nobody's going to be surprised, that's just what happens with electronics - but it's a combination of advances like this (maybe this specific one, maybe others) which drive those improvements.
I 'm no expert and I'm too tired to read the entire linked article but above it says:
"for the first time, and we're told that the arrays can convert between 90 and 100 percent of the photons they absorb"
The question we should be asking is, what is the absorption rate of the panels?
Dose this solve the crisis probably not but its a large step forward.
@andromeda05
I think you will have to wait a bit longer, maybe 10 - 20 years.
@andromeda05 I think the Idea of solar panels is a great thing but not in the current format that governments are placing it at. I'm all for the R&D that is going into the field today but I think that the government payouts for people that are deploying this kind of tech should be funneled into the R&D instead of paying people to use a product they wouldn't be able to afford or better pay for itself otherwise.
We need to look into the tech we have today. IE Nuclear and this Conservative shouted for joy when Obama said he was going to fund nuclear power, and furthermore I want to smack a few Republicans/Democrats who are arguing for the sake of arguing with him about the issue because he wanted to push it, and for the left winged eco people we have 2 choices coal or nuclear that can be deployed today you choose.
@andromeda05 : this is the key question in the short term. But the long term issue is, "how well does it scale?". Sure, that phenomenal efficiency may only be applied to a minuscule amount of photons, but the underlying conversion tech can be combined with some other breakthrough in collection..assuming this isn't just another attempt by a college to scam millions out of the taxpayer. As someone else already commented, that sort of thing is all too common with the big technical schools. They are promising the moon in order to keep the funds coming in.
@psycros I don't care how much we funnel into R&D as long as progress is made America is became the power it is today by funding everything it could get it's hands on not using tech that has a lot of promise before it's ready to be deployed. I believe that was what the old USSR a proved to be too expensive and there not exactly around today to talk about it.
But as long as the school improves on its tech year to year keep giving them money and look for new people to fund on projects that show promise not pay people to save $10.00 a month on a panel that cost them $1000 after government rebate.
My father in law is It for one of the power companies in southern Georgia and his opinion is take away the government money and see what still stands and after some thought I agree.
It's too expensive to do what were doing. Instead of all this nonsense we could have had a Zero emissions USA years ago at half the cost to the customers and have been looking to fund research for ways to replace the reactors instead of arguing on what should be allowed to power homes in the USA.
It's simple Nuclear until something better can reliability take its place.
@andromeda05 I Wish i could edit my post