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A Step Closer To The Optimum Solar Cell
An anonymous reader writes "Besides cost, solar cell efficiency is the second most critical criteria. Scientists from Berkeley Lab and other institutions, have announced a new solar cell material that may be able to achieve an extraordinary efficiency of about 50 percent -- twice the amount of the current record holder."
Ah, an efficient solar cell. This is the last you will hear of this! Halliburton and Big Oil will immediately buy the patent and sit on it, just like they did the antigravity saucer, the 300 mph carburetor, cold fusion, and Skynet microchips from the future. Save your cache while you can!
Don't blame Durga. I voted for Centauri.
In 1999, Walukiewicz and others at Berkeley Lab were working with solar-cell designers at DOE's National Renewable Energy Laboratory, who were trying to build a three-junction cell. The NREL researchers inadvertently created the first photovoltaic semiconductor with a split band gap. But at first they didn't realize it.
...
"They needed a new material with a 1-eV band gap and a crystal lattice structure that matched the other layers of the cell," Walukiewicz explains. "They used gallium indium arsenide nitride alloys in which just a little nitrogen could achieve the desired band gap, and an almost perfect lattice match."
Since the band-gap reduction was unexpected, Walukiewicz set out to find out how it worked. The answer, it developed, was that the few atoms of nitrogen, which are much more electronegative than the host atoms (much more strongly attractive to electrons) produced a narrow energy band of their own, splitting the GaInAs conduction band into two parts. The gap to the lower of the two conduction bands was the desired 1 eV.
In the case of GaInAs, other characteristics of the split bands made for a poor solar cell material. Nevertheless, Walukiewicz and his colleagues continued to investigate the phenomenon and developed a model of the split-band phenomenon known as "band anticrossing."
Yu admits that forming highly mismatched alloys is "challenging from a crystal-growth point of view," but there is hope that crystals can be grown epitaxially (the growth on a crystalline substrate of a crystalline substance that mimics the orientation of the substrate). One good sign, he says, is that Japanese researchers have already grown thick oxygen-doped crystals of a related material, zinc selenium.
http://tinyurl.com/4ny52
I used to jump for joy whenever I saw things like this.
But experience generally showed that Breakthrough X which would produce cheap power/double battery life/allow 5 terabytes in my computer never actually arrived at the market.
I'm still waiting for holographic storage from 10 years ago!
My Journal
The calculated efficiency of a single-junction solar cell made with this material would be a remarkable 57 percent. But while the single-junction architecture is elegantly simple, many questions have to be answered before ZnMnOTe or any of its highly mismatched cousins prove they can do the job.
So not only does it not work yet, but any article that starts off with the words "besides cost..." is obviously talking about an economic impossibility.
We're stuck with cheap oil until it runs out in a few decades. And then we're stuck trying to rebuild civilization with coal.
One things that I've never seen is the lifetime and disposal costs of solar cells . . . that never seems to be factored into the so called "solar renewable energy" equation.
"Something wrong with nuclear power?"
Oh yeah. It is extremely expensive and dangerous, and the waste is so nasty that no-one has found a safe way to get rid of it yet. Cool down, Mr. Burns.
"Sure, fission-waste is not something you want. But it sure beats the crap out of coal."
Really now? OK. You have a choice. A bucket of fission waste under your bed, or a bucket of coal. Which one do you choose?
And the other critical criteria? Such as the inefficiency and byproduct waste of making solar cells in the first place? I'm all for research, but unfortunately we're still a LONG way from using solar power on a large scale. I'd like to hope that's where this is ultimately going.
OTOH, any step forward toward greener energy is good in my book.
"We are the first generation to influence the climate and the last generation to escape the consequences." - John McCain
... Is this material subject to the Stabler-Wronski effect? If so, the claims of 50% efficiency would only hold up for the first few hours of use.
When it comes to adoption of solar power, there's only one calculation that really matters:
C = Cost of installing solar panel
R = Revenue generated (or money saved) per year
M = Maintainence costs per year
(R - M) >= C * 20%
In plain english, when you can get (somewhere around) a 20% return on investment from installing a solar panel, you'll start to see them on top of office building, parking garages, and just out in the middle of open fields, soaking up money.
Until then, solar power will be a technical curiosity for use in special situations (outer space) and for those with a political agenda.
"C = Cost of installing solar panel"
Under Socialism , C always = 0, since the government pays for it. If the government pays for it, you don't have to.
Now we can run 5 100-watt light bulbs per square meter in death valley in full sunlight.
You can tell a great deal about the character of a man by observing those who hate him.
- the peak total of plants are pretty much maxed out and will require building of new plants
- Alternative energy is sporadic and can not be counted on (except for tidal).
Right now, we have money going into generation, but really need to spend it on storage as nothing really works well. I would love to money put into Beoings use of salt and a stirling engine for doing this. But I doubt it will happen.I prefer the "u" in honour as it seems to be missing these days.
...it's Chernobil.
In plain english, there are other design criteria other than a very simple equation even an economist could understand. Economies of scale mean that in most cases it is cheaper for a business to get power from a grid, no matter what powers it.
The bad news is that shortly thereafter, everything will turn an odious dull black.
Is it fascism yet?
You can get around this by using a non-polar solvent instead of water. Liquid carbon dioxide is good for this, with two further benefits:
- CO2 is a byproduct of combustion, so is plentiful, and
- Putting CO2 into the earth is a good way of sequestering it, so using recovered CO2 to dissolve and lift oil can simultaneously help meet CO2-reduction targets.
The real interesting times will come when (I'm sure it's when, not if) energy from solar becomes so cheap that we wind up using it to perform environmental remediation. We might wind up making crude-like oil and pumping it back into the earth just to put excess carbon away. We are already able to make "light sweet" oil from organic goo using thermal depolymerization, so taking it to that conclusion it is only a matter of purpose and scale.Time is Nature's way of keeping everything from happening at once... the bitch.
But that doesn't matter. There is no shortage of sunlight; the problem is the expense of collecting it. This makes the most important metric $/W instead of W/m^2, and cutting $/W is the worthiest goal for the widest variety of uses. To that end, Energy Innovations came up with the idea of a small multi-mirror concentrator system feeding a Stirling cycle generator. 200 watts for $200, or $1/peak watt. The last I heard they had put the Stirling engine on the back burner due to development costs and were going to market with a concentrating photovoltaic system instead. We're going to have to wait, I guess (or license their patents).
Time is Nature's way of keeping everything from happening at once... the bitch.
Tanstaafl
Underground equipment tends to be even more electrified. Here is a photo of a chairlift, yes- like the skiing kind, being used in an underground gold mine in Africa.
-AD
- Cu, In, Ga, Se and S are deposited via a vacuum & diffusion process
- Can be deposited on plain glass (same stuff used for window panes)
- 1 micron of this stuff absorbs more sunlight than 350 microns of Si (about 99% of light - don't know how this translates to efficiency, though - article not too technical).
- Panels like these would cost roughly a tenth of the price of those currently available.
- Pilot plant for manufacturing was expected to begin manufacturing somewhere in April (this month), manufacturing panels 400mm x 500mm @ 20W
- Pilot plant (100 sq m) to cost about US$ 2.3 - probably within reach for many developing countries.
Unfortunalty there's not much more detail or Web references....Free, as in your money being freed from the confines of your account.
Don't use batteries. It's not cost-effective. They're huge, high-maintenance, and have to be replaced regularly. It's better to run a grid-tied system and hope somebody else figures out how to handle storage more effectively.
Nonetheless, I wouldn't suggest to most people that they try this to save money. It's at the point where you can break even in 8-10 years, but that's still the sort of time frame where it appeals mostly to folks who are doing it because they want to, not because it's a financial gain. It is a financial gain when done right, but not for a long time.
- Park them in your garage (at least, not easily).
- Land them in any parking lot, e.g., to go grocery shopping.
- Ride with the top down.
Now, you can do some of these things with ultra-lights, but ultralights aren't very comfortable and don't go very fast.Those who sacrifice security to condemn liberty deserve to repeat history or something. - Benjamin Santayana
Mod parent "underrated"
Mod parent "underrated".
Accounting for clouds and rain would probably reduce the daily sunlight average low enough that energy needs wouldn't be met.
An effective way to use renewable energy exclusively is to build huge solar arrays in space (where there is lots of room) and beam the energy to Earth as microwaves.
Using asteroids, etc., as raw materials will reduce the pollution/energy costs associated with producing the materials on Earth and sending them into space.
The technology to do this is not too far beyond present-day.
The main hurdle to this method will be political (misinformed environmentalists, oil companies, etc.).
Those who sacrifice security to condemn liberty deserve to repeat history or something. - Benjamin Santayana
http://www.ornl.gov/info/ornlreview/rev26-34/text/ colmain.html
- I don't need to go outside, my CRT tan'll do me just fine.
What I meant was to use asteroids as the raw materials for building orbital solar panels.
What would be launched into space would be factories that would capture asteroids and build solar panels out of them.
So we don't have to "get the huge solar arrays into space", because we build them out of material (asteroids, comets, etc.) that is already there.
What has to be launched are the factories.
Or go one step further: launch one or two factories into space that use an asteroid/comet to make many solar panel factories.
Then the solar panel factories will make the solar panels from other asteroids/comets.
This method would require only one or two launches (assuming that the factories are small enough that they don't have to be sent up in pieces), plus maybe a few more to send up components (such as electronics) that are too complicated or require too much infrastructure (e.g., large chip fab plants) to make in space.
Also, once the Space Elevator is built (a little bit further beyond present-day), rocket launches will no longer be necessary.
I have nothing against nuclear energy (I would prefer it to fossil fuels of whatever kind), but IMO, the less mining on Earth, the better.
(Some mining would be necessary to get the materials to build the microwave collectors and rockets, but I don't think that it would be as much as mining nuclear fuel and materials to create nuclear power plants.)
Those who sacrifice security to condemn liberty deserve to repeat history or something. - Benjamin Santayana
When I saw this sign at the cinema from a distance way back when that movie came out, I thought it said: 'Three Men and a Baby PIG' . I couldn't imagine what they were doing with a pig...
In many Mediterranian countries, water is heated using solar panels which utilize the greenhouse effect. The idea is that blackened water pipes are running through a glass panel installed on the roof, facing south. Hot water is stored in a tank. In summer, and in many winter months, this removes the need for heating water electrically. Coming to a sunny part of the US, I was pretty astonished not to find that. Well, at least not in Cali. Makes you wonder why how much this new development will be implemented.
I'd moderate you up for funny if I could. Of course, it's not as creepy sounding as "Three Men and a Little Lady PIG"
You are in a maze of twisty little passages, all alike.
Whether power is produced by centralized nukes, big hydro, coal plants, or solar space satellites beaming power to big rectenna farms on Earth, the power must get to the consumer. Typically that is though an electric grid. Right now, about half or so of an electric bill can be delivery cost -- the cost of maintaining the grid. So, it will make no economic sense to buy power from a grid once local solar falls below about $0.06 / killowatt-hour. This is in about 35 years w/o major breakthroughs by current trends -- faster with a breakthrough like this -- assuming energy efficiency and storage or cogeneration issues are also dealt with cost effectively. Note that even with local solar cells, it may still make sense to have some centralized production of synthetic liquid fuels for use for transportation or backup power using cogeneration especially in northern lattitudes -- solar space satellites might have a role to play in that if we otherwise already have a space industrial infrastructure.
A 21st century issue: the irony of technologies of abundance in the hands of those still thinking in terms of scarcity.