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40% Efficiency Solar Cells Developed
Posted by
Zonk
on Fri Jun 01, 2007 05:28 PM
from the that-makes-me-28-percent-happy dept.
from the that-makes-me-28-percent-happy dept.
gtada writes "A story published at Physorg.com discusses recently published research into the fabrication of solar cells that surpass the 40% efficiency milestone. Such devices would be the high water-mark to date, and hint at the possibility of even more effective technology. 'In the design, multijunction cells divide the broad solar spectrum into three smaller sections by using three subcell band gaps. Each of the subcells can capture a different wavelength range of light, enabling each subcell to efficiently convert that light into electricity. With their conversion efficiency measured at 40.7%, the metamorphic multijunction concentrator cells surpass the theoretical limit of 37% of single-junction cells at 1000 suns, due to their multijunction structure.'"
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Is efficiency the problem? (Score:5, Insightful)
Re:Is efficiency the problem? (Score:5, Funny)
If we run out of coal, we can adapt. But if we blow all our sunlight on inefficient solar cells, the consequences would destroy life as we know it!
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Re:Is efficiency the problem? (Score:4, Insightful)
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Re:Is efficiency the problem? (Score:5, Insightful)
Right now, we've got ~40% efficiency panels which are very expensive, and 1-2% panels which are cheap to make. I think the real breakthrough will be when we can make 20% efficiency panels that are inexpensive enough to cover a roof. So, in the long run, you are right that space will be the overriding factor, but right now it's cost-per-watt that is the biggest problem.
Parent
Re:Is efficiency the problem? (Score:4, Interesting)
Yeah, there's a guy in NJ who went completely solar for his energy needs and spent about $400K on the system, not counting maintanence costs.
If only Moore's Law applied we'd all have a setup like that in ten years.
Parent
Re: (Score:3, Insightful)
If we keep treating energy efficiency like a luxury, it won't be long before we value energy above life itself. Forget 1984, it'll be more like Mad Max.
Re:Is efficiency the problem? (Score:5, Insightful)
This is one of the big challenges facing us - a combination of some raw materials being in short supply (and thus high cost) at the same time, coupled with asset inflation due to other reasons. In some instances the high price will bring in investment to create new mines to create new supply, but this will take a decade or more (assuming new supply is possible). The problems at hand of energy security and of reducing climate change is one that needs to be invested in heavily on a more urgent timescale. If demand drives above supplies of the raw materials and the cost of the raw materials becomes 'real' (i.e. the element due to global liquidity asset price inflation vanishes) and this feeds into general inflation, then interest rates might be stubbornly high which makes long term investment in these technologies more expensive.
In other words the time to have really pushed forward on implementing many of these technologies would have been a decade ago, even with less mature technologies, as the economic conditions were more benign between then and now than they are likely to be between now and 2017. The technologies are still needed, but things will be tougher. The lowest hanging fruit need to be identified and identified quickly.
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Re: (Score:3, Informative)
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You know all of those shiny office buildings in big cities? That's all, wonder of wonders, glass. If you can have an entire 20, 30, whatever-story building with glass exterior walls, you can put some glass on your roof.
Re: (Score:3, Interesting)
I also remain curious about the weight- roofs seem to be supported by thinner and fewer A frames and you can see in many roofs where they sag rather obviously on either side of a beam. Will roofs have to be made stronger to support these heavy glass panels? I thought many of the recent ones were thinner and made with plastics? I saw one on TV the other day that was made to look like that sheet stuf
Re:Is efficiency the problem? (Score:4, Insightful)
It would be great if we could produce solar cells that reduced the amount of CO2 and produced electricity for man to use. If we could do that then we would really not make much of an impact as we "developed" lands.
** keep in mind that the above comment disregards the other effects of "development"
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Re: (Score:3, Interesting)
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Re:Is efficiency the problem? (Score:4, Interesting)
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Re:Is efficiency the problem? (Score:5, Informative)
Not particularly. Because they rely on semiconductors, they only scale as well as the fabs to build them. The problem has been that the solar industry uses plants that are at the end of their semiconductor chip fabricating life; thus they do not wield great efficiency due to small wafer sizes. They also suffer from the base challenges of dealing with silicon wafers (raw cost of wafers, dicing costs, etc.) The same cost problem exists with LEDs. It's interesting to note how GE is focused on cost of production in OLEDs rather than their efficiency on GE's Global Research Blog post [grcblog.com]. Following that analogy, it's not the 40% efficiency that will launch solar cells, it's 10% efficiency at 10% of today's cost (It's about cost/kWh).
Now, if we could only figure out some way for the oil companies to reap massive profits from such a scheme, I'm sure it would happen in no time.
You mean oil companies like BP and Royal Dutch Shell? ... two of the top 6 producers of solar cells? [iea-pvps.org]
I'd note that most oil companies do have lots of research into alternative (non-oil) energy. It's just hard to see in their financials because oil is so lucrative. The major one that realy gets criticized for its lack of investment in areas like solar is ExxonMobil - and the reason they don't is probably the same reason that Cisco doesn't tend to develop most of its revolutionary technology inside the company. XOM and CSCO both have tons of cash, tons of cash flow and a well-priced stock giving them the ability to simply buy a producer of new equipment if it becomes a valuable market. Why bother to spend tons of money on basic research when you can let the newcomers fight it out in the market and just buy the leader when the time is appropriate? As strange as it is, that's R&D economics at many large industry-leading corporations. It's "efficient outsourced innovation" [businessweek.com].
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Re: (Score:3, Insightful)
Re: (Score:3, Funny)
Re: (Score:3, Informative)
No, *that* is an incorrect statement. I think you're mixing up UV transmission with visible spectrum transmission. Clouds absorb and reflect 35-85% [phelsumania.com] of radiant energy. Even worse, cloudy-day sunlight is diffuse, so you can't optimize your panel angle effectively and you have no choice but to suffer flat plate losses.
Clou
Re:Is efficiency the problem? (Score:5, Informative)
You might want to investigate it yourself - just pop over to Seattle City Light on the City of Seattle website and read up on it.
Now, the solar cells we use to POWER some of our public buildings, bus shelters, and schools here are not as efficient as the 40 percent that this Letter in Applied Physics speaks of, but they are about half as efficient.
Cloud cover as you understand it, depends on visible light spectra. The solar cells absorb far wider bandwidths, at least the ones in common use here.
If we were a snowbound or ice-storm city like many others - which we are not - it is possible that your statement would be less inaccurate, as the ice crystals and heavier cloud formations might refract more of the effective solar energy, but we tend to only have a mild drizzle due to the consistency of our cloud cover.
Or haven't you noticed?
Don't believe me? Go look at the bus stops with LED readouts along N 45th, some of the public schools (including two my son went two and the high school he's in now), and even Seattle Center's public meeting rooms.
See - solar cells. Perfectly happy solar cells.
Some people use solar water heaters on their rooftops here, and if you look around Phinney Ridge you'd see a few of them. There's a reason they're frequently referred to in the Seattle Times supplements on Green Houses - people USE them. Because they make sense here.
Here endeth the lesson.
Parent
Re:Is efficiency the problem? (Score:5, Informative)
The fact of the matter is that no matter how efficient a cell is on cloudy days, there just isn't as much energy available on cloudy days as on sunny days. A heavy overcast probably has 15-30% of the energy as a sunny day, which is certainly better than zero but is a major hit if you can't count on some sunny days to "make hay" on.
Also, efficiency matters to people with limited space in which to install solar arrays. Of course, current production crystalline technology has cells with efficiencies in the high teens, but when packaged the overall efficiency usually drops to the low teens for a number of unavoidable reasons.
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Re:Is efficiency the problem? (Score:4, Insightful)
No; it's clearly an evil oil company conspiracy.
(Note: not every oil company is diversifying into renewables. Some dinosaurs, like Exxon-Mobil, resist it like the plague. But many are.)
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Some important notes... Oil is in the $60/barrel range (you can go check commodities but it's there +/- $10 from my recollection).
A barrel of oil has 42 gallons
In refining, typically a bit over 50% makes it to auto gas:
http://www.energy.ca.gov/gasoline/whats_in_barrel_ oil.html [ca.gov]
So we're talking $50 to $60 to get 21 gallons of motor fuel. That's a fair chunk of change.
Oh, and I found this all in about 30 seconds with Google. Ever heard of it?
Buy gallium futures? (Score:5, Informative)
It's another gallium-based technology. That's going to limit it. There's just not that much gallium available. 30%+ efficient cells using gallium have been around for a few years, but other than on spacecraft, and the Stanford Solar Car, they're too expensive to be useful. They talk about "concentrator cells", but that means mirrors and trackers, running up the system cost.
Citation: King, R. R., Law, D. C., Edmondson, K. M., Fetzer, C. M., Kinsey, G. S., Yoon, H., Sherif, R. A., and Karam, N. H. "40% efficient metamorphic GaInP/GaInAs/Ge multijunction solar cells." Applied Physics Letters 90, 183516 (2007).
To the moon Alice! (Score:4, Interesting)
Parent
no (Score:5, Insightful)
not even remotely. plants are efficient at converting photons to an immediate energy source but the vast majority is used to keep the existing tissues alive and functioning. esimates I have seen for the efficiency of converting light, CO2 and water into biomass ranges from less than 1% to 5% depending on the species.
Efficiency (Score:5, Funny)
Hmm.
Re:Efficiency (Score:5, Informative)
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Re: (Score:3, Interesting)
What isn't being trapped by jumping electrons (that other 60%) is going to go into heat - what we need is a heat engine on the back side of the cell recovering that other 60% ...
Re: (Score:3, Informative)
However, if you want heat, rather than work, you should be able to collect all of that 60% - thermal desal, domestic hot water, space heating - all are easily
The main issues (Score:3, Insightful)
- Efficiency: This article talks about brightnesses of 100 suns. Well what about 1 sun? Or fraction of that (cloudyness)? Are these efficiencies realized then too? If not, does the technology still work at or near where that is?
- Power cost: I've seen it said that many solar cells don't give back the energy required to manufacture them. By that I mean, acquiring the materials (mining, etc), refining them, and manufacturing them all take energy. How many days/months/years would it take to "pay back" the cost of manufacture, in energy?
- Temperature performance differences: How does it perform in low (or high) temperatures? A lot of us live in places where it gets cold for long periods of the year. This also has the associated problems with snow build-up, and getting that OFF of the panels.
- Monetary cost: How much will this cost at the consumer level, for which wattages? How big would they have to be to cover some typical consumer usages?
- Power storage: With solar, it all eventually comes back to storing the power, as they obviously don't operate in darkness. So how much would the batteries cost (initially, and in maintenance) to make this a viable power solution? How much wattage would you need to have enough "storage" for nighttime? Or more practically, for a few cloudy/rainy days in a row?
Some of these issues are universal to ANY solar technology, but some of them are specific to this as well. All need real answers.Re:The main issues (Score:4, Insightful)
1) Efficiency and measures of "suns": As others have explained better than me, this basically means that they are using mirrors to "collect" the sun power and focus it.
3) Temperature: Solar cells tend to work better in colder weather, as you have less heat transfer loss. It just so happens that many (but not all) places with lots of sunlight happen to be hot -- but cold weather is actually a bonus factor. Generally, your efficiency losses resulting from hot weather are roughly equal to the reduction in power you get from being in a less sunny place, all other factors being equal.
4) Monetary cost: Solar is expensive. No question. But isn't it worth it?
5) Storage: Unlikely to be an issue. Aside from specialized case (read: nutcakes living off the grid or places where power isn't essential), solar is a peaking power resource that's used in conjunction with conventional generation technologies. At night? Pull your power from the grid. During the day? Send power back onto the grid (a.k.a. net metering). Much more efficient than trying to generate the power and store it.
Further, the suggestion is definitely that this would be used in utility-scale applications, given the concentration of sun you need to have. So again, batteries are not really an issue, as any power sent out onto the grid is instanteously (or pretty damn close to it) consumed by a thousand hair dryers all running at once.
Parent
Re:The main issues (Score:5, Informative)
If solar is less expensive than the available clean conventional sources then this might make sense. Otherwise, why bother? It's only in situations where you're already near existing daytime conventional capacity and the deployment of solar is much faster/cheaper in the short term than deployment of another clean conventional source that it might make sense. But if solar is expensive and/or time-consuming to deploy (relative to deploying another clean conventional source) then it simply doesn't make sense to use it even if it's only for dealing with peak load.
Forgive me, but you are completely wrong about this. Peak periods are exactly when things like solar really "shine." There are a couple thing you must understand about the interstate electricity grid:
First, is that it is over-designed on purpose. Most major utilities have operating reserves of power generation of between 12 - 18 % of the day's anticipated peak demand. On any given day, the system operator will have tens or hundreds of generation sources that it never dispatches (e.g., uses to produce power), but that are there "just in case." This means that utilities have multiple dispatch solutions in order to meet load (load being a measure of people who want to use electricity).
The second key principle is that utilities select their generation resoures based on a "least-cost dispatch" basis. While in practice, this gets incredibly complicated (and also includes environmental factors), the utility will pick the least expensive generators that can produce enough power to adequately supply the day's demand. In practical terms, this means that the utility will dispatch the dirtiest and most expensive to operate (on an incremental cost basis) generating facilities last.
The third principle is an outgrowth of the first two. On peak demand days (think middle of summer, air conditioners running at full blast, etc.), the number of dispatch options available to the utility decreases further and further as it commits an ever-increasingly greater share of its total generating capacity to meet demand. This means that your nastiest, dirtiest, foulest, most expensive generating facilities are dispatched on such days.
Imagine this scenario. You are Utility X. You have the following five generating facilities at your disposal:
1000 MW nuke.
500 MW cheaper, clean(er) coal.
500 MW slightly less cheap dirty coal.
100 MW incredibly expensive natural gas.
20 MW aging oil burner that spews out more toxics that Paris Hilton on a breathalyzer AND costs more than the GDP of small nations to operate.
Total installed capacity (a fancy term for the total amount of generation): 2110 MW.
Now imagine that hellishly hot day. Demand immediately soars to 1500 MW -- and it's not even 11 am yet. You commit your nuke and your clean coal facility. Now it's 2 pm and demand hits 2000 MW. Throw in the dirty coal. Four pm rolls around and demand hits 2040 MW. Thow in that expensive natural gas peaker! (Don't worry -- the rate payers will just end up eating the extra -- your investors are safe.)
Now it's 4:47 in the afternoon. The peak of the peak. You're at 2099 and still rising.... You are getting ready to commit the oil burner at a cost of several millions of dollars and countless hazy days. Do you need it?
Well, maybe not. If you were a smart utility executive, you invested in Demand Response and paid some of your customers to go off-grid on days like this. Additionally, you've been incouraging customers to install solar panels that are all furiously generating power right as it's needed most.
This is the moment where solar pays for itself. By reducing the peak demand by only a smidge, you reduce energy bills substantially. Solar is also one of the few alternative/clean sources of energy that peaks along with demand. Wind, for example, tends to blow off-peak. (This is even more true when you facto
Parent
Re: (Score:3, Interesting)
With solar, it all eventually comes back to storing the power, as they obviously don't operate in darkness. So how much would the batteries cost (initially, and in maintenance) to make this a viable power solution? How much wattage would you need to have enough "storage" for nighttime? Or more practically, for a few cloudy/rainy days in a row?
There are several options other than chemical batteries. Pumped-storage hydroelectricity [wikipedia.org] is commonly used, but it's inefficient (for example, Northfield Mountain [wikipedia.org] only returns ~35% of the energy that's expended pumping the water uphill). Flywheels [wikipedia.org] are very promising. I read some interesting articles [www.mega.nu] in the 1990s about using them in electric cars, but that presents various challenges (cost, gyroscopic forces, what happens when a car crashes, etc). Even if we can't get that to work, is seems like they're a
Re:The main issues-Power cost (Score:5, Informative)
So yes, this depends highly on the materials used and manufacturing process as to whether the energy payback is an issue or not. 1-20 years? Let's hope this technology is on the low end of that scale.
Also, two more issues came up that I forgot in my original post:
- Exotic Materials: The materials advertised in this article are not... common. I highly doubt this helps either the mass production price, or the long-term availability of such.
- Lifetime: How long does a panel actually last? Few manufactured items of any kind have infinite lifespans. Is the manufactured solar cell "stable" chemically/physically? This ties in slightly to my old heat/cold question, but when stressed by weather, will it hold up?
Most of my questions are challenges to be overcome, not "Death knells" to trying. But they're also things to be aware of when anything's announced with too much enthusiasm.Parent
suns (Score:5, Informative)
when the article talks about hundreds or thousands of suns, it means they used mirrors and lenses to concentrate the light that falls on a much larger area to then fall on the solar cells. this leads to the solar cells generating a lot more electrical power and thus makes it more economical to produce power from soalr energy as compared to not using mirrors or lenses to focus light onto the panals.
Cut to the Solar Chase: Nuclear Reactions. (Score:4, Insightful)
As another posted stated, even if you make the solar 100% efficient (wouldn't that be something!) you still have to store or transport it - since on average the sun is hitting half the Earth's surface at any given time (with much of that surface being water).
I have high hopes for solar - but it always strikes me as strange that we already have this amazing technology of nuclear power - it's here now! We HAVE it!
Plus, nuclear power can make a nuclear rocket! I don't know of any solar rockets yet.
Re: (Score:3, Informative)
http://en.wikipedia.org/wiki/Solar_sail [wikipedia.org]
Lunar power is SO underrated (Score:5, Funny)
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Studebaker Nuclear Reactors (Score:5, Interesting)
Only with stupid old technology. The Integral Fast Reactor [wikipedia.org] generates 100 times less waste and it's only hotter than ore for a few hundred years. We should be building one at Yucca Mountain as a national security priority.
Fusion will be great in 40+ years, but that's a little late to act. We could have one of these running in probably 5 years.
Solar, at 40% efficiency would still require covering something like 8% of the land surface area of Earth to meet current-day demands. Wind is too variable, hydro is too small - we basically have coal and nuclear as the two viable baseload options.
Obviously, TBPB don't want to end anthropogenic global warming. It's left as an exercise to the reader to speculate on why.
Parent
Re:Studebaker Nuclear Reactors (Score:5, Insightful)
You might want to re-check your calculations. Total world energy usage is ~15 TW. Light at surface averages ~342 W/m.
Land surface is 148,939,100 km
(1.5*10^13 TW / [0.4 *342 W/m]) / 148939100000000 m = ~ 0.07%. Let's double it for extra capacity (and because half the planet is in night), and we're still under 0.15% of the land surface area. Your 8% estimate is large by a factor of 50 or so.
Of course, putting the whole thing in space might make more sense. If you really want pie-in-the-sky thinking, covering the moon with 10% efficient solar cells would provide about 86 times the power the world uses now. Getting it all back to Earth would be the tricky part.
Though I also agree we should be using better nuclear reactors.
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Re:Studebaker Nuclear Reactors (Score:5, Informative)
Would UC Berekeley's Nuclear Engineering department be a reputable enough source for you?
They quote [berkeley.edu] less than a ton of waste per GW-year. Conventional is about 35 tons per GW-year.
I'll make a note to find the reports from the Argonne Labs prototype when I get some library time in.
Parent
Re:Cut to the Solar Chase: Nuclear Reactions. (Score:5, Insightful)
The Russians cut stupid corners in nuclear power. Not only did they use a graphite-moderated reactor at Chernobyl, but according to your linked article, they didn't glassify (or recycle) their nuclear waste. Furthermore, I doubt those rods have a high enough concentration of plutonium to actually explode. The article was a little light on the technical details.
Also, waste is not "just so dangerous." By the very definition of half-life, the most intense radioactive waste is the stuff that breaks down the fastest. That's why we keep it in cooling ponds for a few years before doing something else with it. After the high-radioactive components have decayed, what's left has a very long half-life, which means that it has a low level of radioactivity.
Besides, if at that level of radioactivty, you feel the need to manage waste for 10,000 years, how about managing our copper and gold mine tailings, which are killing our rivers? Or how about managing our toxic chemical waste, repairing underground gasoline tanks, cleaning up rivers that are so toxic that we can't eat fish out of them, and so on? What makes low-level nuclear waste more important than these more pressing problems?
And as for accidents -- all industries have accidents. A chemical plant caught fire a few years ago and poisoned hundreds. But look at it this way: we only have two choices for energy for the next hundred years: coal or nuclear. Even if we do have a nuclear accident or two (which is highly unlikely, given the paranoia surrounding regulation of nuclear facilities), nuclear power would hurt and kill fewer people than coal will.
Also, France uses nuclear power for 90% of its electrical needs. When's the last time you heard of a problem at a French power plant?
Parent
Re: (Score:3, Insightful)
As for fusion fuel -- it's an oft-repeated fallacy that we only have a tiny bit of that stuff. That view is terribly wrong. See this article [world-nuclear.org]. The gist of it is that nuclear fuel is limited only under these flawed assumptions:
Re: (Score:3, Interesting)
Sigh. Everytime I criticise nuclear power someone brings up the strawman of coal power. Next time, I must remember to address it first.
Yes, coal is terrible. Yes, we should stop burning it. Yes, nuclear is probably better than coal.
BUT, renewables are better again. If we're going to change our infrastructure, why settle for second-best? Why not change to wind, solar and tidal, and have the best power source (and maybe use nuclear a _little_ bit, where necessa
Re: (Score:3, Informative)
Dupe from December (Score:3, Informative)
Ahh well. More publicity for Spectrolabs...
enough power for laptops (Score:3, Insightful)
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