40% Efficiency Solar Cells Developed

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.'"

Comments

Is efficiency the problem?

[timeOday]

There is really no shortage of sunlight anyways. If only solar cells could be made cheaply. I suppose this will be great for satellites though.

Re:Is efficiency the problem?

[provigilman]

There's no shortage sunlight, true...but there's a shortage on space. Our energy needs to continue to grow more and more every year, theoretically it could get to the point where we have to cover large amounts of the planet's surface with solar collectors. The more efficient each individual collector is, the fewer we need and the less space they'll take up.

Re:Is efficiency the problem?

[SnowZero]

While space will eventually be a problem, I think cost is still the limiting factor right now. How many houses can afford to cover their entire south-facing roof with panels right now? If you see panels on a house, its usually only covering a fraction of the available area, which implies the limit is cost.

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.

Re:Is efficiency the problem?

[Rei]

You're right. It's all a conspiracy. It's not like oil companies spent almost half of the world's investment in renewables R&D and produce almost as sizable chunk of renewables products or anything. It's not like there are companies out there with names like "Shell Solar" and "BP Solar" out there producing massive numbers of solar cells. Or like Shell is the largest investor in the world's largest wind plant under construction. Or anything like that.

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.)

Re:Is efficiency the problem?

[billcopc]

Part of the problem is we're still working against each other when it comes to energy. $400K of solar power equipment isn't the cost, it's the sale price. How much of that went to the various middlemen involved ?

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?

[jessecurry]

Interestingly enough the entire planet already is covered with solar collectors... well all of the planet that is "untouched" by man.
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"

Re:Is efficiency the problem?

[Alpha830RulZ]

I'm sorry, that's just paranoid. Check out the financial statements of Evergreen Solar, or Corning, two of the producers of panels. They're not printing money. It is a fact that it is not yet economical to power your house with solar, and it's due primarily to the cost of manufacturing the panels. The costs -are- declining, but it's not yet cheaper than coal, hydro, or nuclear. Of course, those sources have significant external costs that are not factored into their market price. When we think through how to tax and charge for these sources of power, the balance will flip over towards more of the solar installations. As production rates rise for these, the cost will drop, and it will become feasible for most of us.

I just priced out a full solar electric replacement for my house in the Seattle area. I think I could power my electric needs (I have gas heat) for a capital investment of about $40k. The payback, even after significant subsidies from the state, was something like 17 years. That's not gonna get Ma and Pa America to convert yet. Once power rates double, and they will, it starts to become close to interesting. When the power rates double again, and they will, the world will convert.

Re:Is efficiency the problem?

[Anonymous Coward]

One of the difficulties that may prevent this as that some of the materials required for these systems have undergone quite considerable asset inflation - rare earths, copper, etc. This is partly because reserves of these elements are dwindling, partly because the machinery to mine them relies on machinery powered by oil derivaties which are more expensive, and partly because high global liquidity and low interest rates has led to a possible asset bubble in a number of assets. If cost drops to that of a car in 2008 then increased demand will then cause those raw materials to increase a lot in price, in which case the cost will then go up meaning a price of more than a car in 2009.

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.

no

[wizardforce]

Suppose I just dump a bunch of Algae in a pond, then scoop off the top flotsam once a week, dry it in the sun, and then burn it? Would this be more or less than 40% efficient?

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.

The main issues

[Erioll]

The main issues with this are:

1. 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?
   
2. 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?
   
3. 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.
   
4. 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?
   
5. 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

[sampson7]

There are a lot of problems with the premises of your questions. But a couple of the easy ones:

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.

Cut to the Solar Chase: Nuclear Reactions.

[TheLazySci-FiAuthor]

Solar is by far my favorite power source. But like every other power source, it is really just a byproduct of the actual energetic reaction. I think I can accurately say that solar power is second-hand nuclear power. Following this reasoning the other power sources may be seen as third-hand nuclear power.

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:Cut to the Solar Chase: Nuclear Reactions.

[QuoteMstr]

Nuclear power production produces a lot less waste than coal mining alone does, and that's not even counting the radioactive dust that coal power plants spew into the air.

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?

Re:Studebaker Nuclear Reactors

[thisissilly]

Solar, at 40% efficiency would still require covering something like 8% of the land surface area of Earth to meet current-day demands.

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.