Breakthrough Efficient, Paintable Solar Cells

An anonymous reader writes "A new solar cell material has been discovered that converts 30% of the sun's energy to electricity." Here's another solar news story. These new cells can harness infrared light which is why they are so much more efficient.

Comments

How much $$$?

[l810c]

If it's that easy to paint on and is that efficient, why are we talking about geek clothes and not about every home having their southerly facing side painted with this stuff?

It must be expensive.

Re:How much $$$?

[stupidfoo]

Because that would make too much sense.

If it was actually true that they had this paint there would be no need for power plants anymore. Just paint all the houses and buildings and you're all set.

Re:How much $$$?

[plover]

Because it was just invented. RTFA, the research was published Sunday.

Who knows if it will be expensive, cheap, emit toxic byproducts, or even be producable in consumer quantites yet? It's just research, not a factory.

Excellent...

[inkdesign]

.. as I've really been burnt up about the lost energy from my remote controls!

Woo

[grub]

So if I spray that on my tinfoil hat and run a couple of leads to my laptop I could have unlimited power!

Re:Woo

[Anonymous Coward]

So if I spray that on my tinfoil hat and run a couple of leads to my laptop I could have unlimited power!

But is it worth the risks? If I undrstood the article correctly you'd have to go outside...

How much energy?

[DaveInAustin]

One key thing that isn't answered in the article (or almost any other articles about "alternative energy sources). How does energy does it take to make this material compare with home much energy it can produce?

Re:How much energy?

[ThosLives]

This is irrelevant for something like a solar cell. A solar cell might take lots of energy to produce, but as long as there is the correct incident radiation and the device works, it will produce energy. For instance, say, it takes 10 MJ to produce one of these capable of produce one watt. The 10 MJ will be made up in 10 million seconds, which is not quite 4 months. (1e7 seconds / 86.4e4 seconds/day = 115 days and some change.) My guess is that's on the right order of magnitude.

Note that this material doesn't "produce" energy at all - it just converts it from the sun (which is the thing sending all the energy our way in the first place). This is different than, say, hydrogen, which is an energy storage medium; you have to put energy into hydrogen to store it, then you get a little less out. With these, you simply build the device, then use (solar) radiation to create a current.

Re:How much energy?

[doinky]

From wikipedia:

"A common myth is that the production of photovoltaic cells requires more energy than these cells produce in their lifespan. Modern cells typically require two to six years to pay back the energy investment made in them, and their lifespan is around 30 years."

We're gonna need all that electricity...

[razmaspaz]

converts 30% of the sun's energy to electricity.

We are gonna need all that electricity because if the sun is 30% smaller than it was before this thing our heating bills are gonna go way up!

Question from the wife of the future

[Anonymous Coward]

Does this recharging unit make my ass look big?

How do we paint it on the Sun?

[tallbill]

OK, I am being silly, what the thing should read of instead of
Converts 30% of the Sun's Energy to Electricity

Perhaps what they mean is
Converts 30% of the incident light energy to electricity

After all, the Sun is realeasing a lot of energy, most of which will never hit the Earth.

Potential != Realized

[Daxton]

If you check the original press release, you'll notice UT says the 30% efficiency might be realized "with further improvements in efficiency". The reporter for CTV missed that little nuance.

Believe it when you see it

[markus_baertschi]

I'll believe it when I can buy it for a reasonable cost at a store in town.

For years we have every couple of months there a new revolutionary way to convert solar rays to electricity. Unfortunately none has managed to work in the real world except the good old silicon solar cells.

Markus

Painted shirts?

[strider_starslayer]

I notice his primary theoretical application was painting shirts so that you can charge your Ipod. What about buildings damnit!

With a nearly 5x increase in power efficency, and the ability to simply paint it on this material strikes me as being ideal for partially powering houses. You paint your roof every summer (Or if the paint is particularly durable every 5 years) and get a grid tie in possibly paying nothing during particiarly sunny monthes.

Of course I supose it ultimately comes down to how expensive this stuff is. When I last looked into solar grid tie ins, it would have cost about 30,000 (cdn.) to get only a few kilowatts of output- the panels were insured for 25 years; and it would have taken 20 for them to pay for themselves, and that dosen't count the concept of any of them breaking in heavy hail, or snow buildup. Not a great investment.

If this paint is durable enough to be put on clothes, and cheap enough to have that done as well, I think that painting the roofs of houses should be the primary applicatino, not keeping all your portable gadgets charged...

Re:Hate to be a Pessimist, BUT.....

[tallbill]

Start your own energy company.
Invest in a technological breakthrough.
In a Free Enterprise system you are free to do that.

You don't have to wait around for anyone else, do it yourself.

There is nothing wrong with big profit as long as you don't enslave people in the process. Also, if you make a lot, then you can share a lot.

Wealthy and powerful people are not categorically and necessarily greedy and selfish as you seem to imply with your post. But being wealthy and powerful makes one (I believe) more susceptible to personality traits that are loathsome to many others.
With great wealth comes great responsibility. Wealth in this sense is a curse. But the curse can be overcome.

POTENTIAL 30%, not actual

[starseeker]

Slashdot does this every once in a while - announce some tremendous new solar energy technology. Folks, it's not easy to get 30%. And even if you do, you haven't won the war. The best, most expensive cells can make those ranges, but they are not something you can put on the assembly line.

I did some research into Cu(In,Ga)(S,Se) thin film solar cells, which have long been a promising material for this type of application. I don't claim to know all about the various options out there (there are a lot of them) but I feel I can safely say there just aren't any magic bullets to this problem. Let me give you some idea of what has to happen.

a) You need a cell with a high enough efficiency to make the power it can produce worth the hassle of installing it. This is hard and the focus of most solar cell research.

b) Even if you GET that cell, you have to be able to make a LOT of them. Cheaply. Very cheaplly if you want to compete with grid power.

c) These materials have to stand up to long term punishment, intense thermal cycling over the course of day and night temperature shifts for twenty years, etc.

d) You have to install the supporting systems - either connect it to grid, get a large energy storage array (i.e. batteries) or both. If you want a battery based local storage system that gets expensive, all by itself.

e) You need to build the industrial support required to make large scale deployment both possible and cost effective. Si, the current dominant material, has a lot going for it because a lot got learned over the course of decades of semiconductor technology. Those tools are somewhat applicable to Si. If you want to use something totally different (i.e. a thin film) you have to make all the gear more or less from the ground up. That's a big initial capital investment for a dubious return.

f) If you want flexible solar cells, you have a whole new set of problems to handle/test, like how the cell performs while being folded repeatedly in different temperature conditions, creased, beat up generally, etc. And flexible cells are a bit of a specialty market - the military likes the idea, sports folks like it, but for large scale fixed installation use (i.e. where bulk production would happen) flexible isn't all that critical. (Although it is nice when it comes to things like roofs withstanding hail storms, but apparently regular ones don't do so hot there anyway.)

g) THEN, after you solved the problems of cost effective production, storage, retrofitting of housing, etc. etc. etc. you have to convince people it's worth the trouble to install it. And I remind you this is the land of the SUV, so I wish you luck with any marketing effort that can't say "We're cheaper than grid power!". Grid power is CHEAP. VERY cheap. It's a really really hard target to hit, and the solar cell technology available today just isn't there yet. There are lots of "potential" 30% configurations - all you need to do, in theory, is have a multijunction device with the right bandgaps. But let me tell you, it ain't easy.

Now, somebody might make a sudden miracle discovery of a cheap 30% cell material. Such things do happen. But I'll want to see a lot of (reproducable) proof, and peer review, before I'll buy it. It's good advertising to claim high performance, but I'll be impressed when someone goes through the nitty gritty and comes out with a viable product.

Re:POTENTIAL 30%, not actual

[Anonymous Coward]

2 comments...

But first, my background...

I actually read the journal paper.

I work on related projects in graduate school, including polymer solar cells, and prior to that worked for a company developing quantum dots for other applications.

1.) The 30% is the theoretical power conversion maximum for a solar energy conversion with a single layer device; they only got a small fraction of this. You could only get this maximum if you had a material that absorbed every photon in the theoretically correct range, every one of these photons created an electron, and every electron came out of the device -- not an easy task, and 30% is the best you could do. The reason there is a 30% maximum is simple -- the device only puts out a single voltage, corresponding to the point of longest wavelength (lowest energy) that the material absorbs. This voltage is the same for all electrons that are generated from each photon. This means all those blue photons become just like the IR photons -- they give up a bunch of energy.

2.) The materials would be cheap. Quantum dots are not exotic. They're just little chunks of semiconductor. They are called quantum dots because their size is such that they have what are called quantum size effects. They are made from soap and metal salts. Massive production would be cheap. The polymer would be cheap to mass produce, as well. The problem is sandwiching it between electrodes -- you couldn't just paint it on without this.

So, basically, this isn't a huge advance... It's the normal stepwise improvement. They took existing technologies that are available, combined them and hyped them up a lot.

Interesting quote

[one9nine]

"When you have a material advance which literally materially changes the way that energy is absorbed and transmitted to our devices... somebody out there tinkering away in a bedroom or in a government lab is going to come up with a great idea for a new device that will shock us all," he said in a phone interview.

I hope he means "shock us all" figurativley.

Re:Okay since heat is IR...

[elgatozorbas]

For starters: heat is not the same as IR. ALL bodies (except perfect reflectors) at nonzero temperature radiate ligth. For very hot ones, this is visible, for rather cold ones this is IR (i.e. 'below red'). You can also heat something by shining other than IR light on it.

These devices don't suck the radiation out of stuff, just like a (digital) camera doesn't suck light from the object you photograph. You can therefore not use them to cool anything, afaik. CPU coolers suck heat out of your cpu because they offer it a lower temperature, and heat flows from low to high temperature.

These things are different from a thermalcouple in the sense that they are in a completely different ballpark. A thermocouply supplies you with electricity as long as you can maintain a temperature difference over it, or it will drain heat from its cold side and add it to its hot side (increasing the difference) if you supply electricity to it. The things in the article supply you with electricity when you shine a light on them and are probably destroyed when you supply electricity to them.

Z

Re:Only at the poles, for half the year

[Surt]

There's this clever thing called power storage. You use your power to reform some hydrogen, and it makes this fascinating device called a battery.

The battery drives your house power needs over night.

Paintable solar cells. Not the first ones...

[Spy der Mann]

2002 CNN article about "paintable solar cells".

The advance in here is that these new cells also use infrared. Also, solar cells are only ONE of the possible applications of this new technology (Nanoapex news article).

Re:Only at the poles, for half the year

[darthdavid]

Actually, a much better way to store electricty is to have a massive resivoir that fills with water using pumps driven w/ excess power during the day and then drains out turning the pumps backwards as turbines at night. Very efficient.

Re:Only at the poles, for half the year

[Rei]

The "5 fold efficiency" gain thing is a bit deceptive. Read the articles carefully: They're comparing a basic organic solar cell with the combination of this organic solar cell with the best (expensive and inflexible) inorganic solar cells to handle the visible spectrum. If you combined this with another plastic cell, you'd end up with a far lower conversion efficiency (although it'd still be a big help).

There are lots of neat solar tech innovations on the horizon, mind you - however, each one tends to address a single issue, and there are many involved in solar. This one addresses capture of infrared on an organic cell. Some other ones that have good potential are things like using a thin layer of luminescent material over/in the cell to downconvert the light (many luminescent materials absorb UV and release the energy in the visible spectrum).

I think that, in 5-10 years if tech keeps advancing this way, we should be able to get organic cells that'll approach the efficiency of today's polycrystaline cells. Which is good, because the silicon cells are expensive :P My partner and I have been looking at installing some in the future, and it'd cost 20,000-30,000$ just for the cells to supply our house's energy. And weight is a definite factor - you have to get an inspection to see if they'll weigh too much for your roof, and if they do, you have to pay for reinforcement of the roof before installation.

Solar everywhere

[gaijin99]

Actually, there's a mall in southern California with a solar panel covered parking lot. Keeps the rain off, keeps the customers cool as they go to their cars, and it just about pays for the mall's electric bill.

The twin problems are initial expense (which with traditional solar panels is horrible, typically you can expect economic breakeven (at today's wholesale electric prices) in around fifteen to twenty years), and the fact that we can never base our entire power production on (ground based) solar. Solar can be used a lot more than it is, but we can't do everything solar because we don't have a good way to store electricity.

Re:Solar everywhere

[Rei]

Depends on where you are. Combination hydro/solar is a pretty good one. Also, daytime tends to be peak-load anyways. Plus, you can give discounts for surplus energy times and reductions in cost for reduced energy times - while this won't change your typical homeowner's habits, energy-intensive industry (for example, aluminum refining) will certainly pay heed. Lastly, at the very least, you can always simply electrolyse water and then recombine it at a loss during times of need.

If they can get cheap power out of solar cells, the varying production levels won't be the issue. Of course, these aren't actually low-cost efficient cells; read the article more carefully. The 30% number, unlike the 6% number, is for this tech *combined* with the best solar cells out there (which are not lightweight, spray-applicable, or cheap).

P.S. - the parking lot uses solar cells? Geez, they better be coated with a pretty thick layer of a high traction, low wear, transparent material, or they'll get torn to shreds and you'll have cars sliding all over the place... Still, if they can manage, organic solar cells would be a good application for that space.

Re:Only at the poles, for half the year

[cbiltcliffe]

High inefficiencies? What are you talking about?

http://www.nmsea.org/Curriculum/7_12/electrolysis/ electrolysis.htm

Take a look at the section headed:
"Specific things you can point out:"

"....electrolysis can be (and is) performed at very high efficiencies close to 100%."

It's probably one of the most efficient energy transformation methods we know of. It's not exactly quick in most people's experience, because the usual public school science projects use electrodes that are way too small.
The biggest I've currently used was about 6-7 square inches of stainless steel, and used a total of 12 milliamps at 14 volt.

Re:Only at the poles, for half the year

[pclminion]

Nope. Hydrolysis is close to 100% efficient. Use your brain and think about it. If it was highly inefficient, where is the waste energy going? Water undergoing hydrolysis doesn't get hot. Try it yourself!