World record solar cell with 44.7% efficiency

Sep 24, 2013
World record solar cell with 44.7% efficiency, made up of four solar subcells based on III-V compound semiconductors for use in concentrator photovoltaics. Credit: Fraunhofer ISE

German Fraunhofer Institute for Solar Energy Systems, Soitec, CEA-Leti and the Helmholtz Center Berlin announced today that they have achieved a new world record for the conversion of sunlight into electricity using a new solar cell structure with four solar subcells. Surpassing competition after only over three years of research, and entering the roadmap at world class level, a new record efficiency of 44.7% was measured at a concentration of 297 suns. This indicates that 44.7% of the solar spectrum's energy, from ultraviolet through to the infrared, is converted into electrical energy. This is a major step towards reducing further the costs of solar electricity and continues to pave the way to the 50% efficiency roadmap.

Back in May 2013, the German-French team of Fraunhofer ISE, Soitec, CEA-Leti and the Helmholtz Center Berlin had already announced a solar cell with 43.6% efficiency. Building on this result, further intensive research work and optimization steps led to the present efficiency of 44.7%.

These solar cells are used in concentrator (CPV), a technology which achieves more than twice the efficiency of conventional PV power plants in sun-rich locations. The terrestrial use of so-called III-V multi-junction solar cells, which originally came from space technology, has prevailed to realize highest efficiencies for the conversion of sunlight to electricity. In this multi-junction solar cell, several cells made out of different III-V are stacked on top of each other. The single subcells absorb different wavelength ranges of the .

"We are incredibly proud of our team which has been working now for three years on this four-junction solar cell," says Frank Dimroth, Department Head and Project Leader in charge of this development work at Fraunhofer ISE. "This four-junction solar cell contains our collected expertise in this area over many years. Besides improved materials and optimization of the structure, a new procedure called wafer bonding plays a central role. With this technology, we are able to connect two semiconductor crystals, which otherwise cannot be grown on top of each other with high crystal quality. In this way we can produce the optimal semiconductor combination to create the highest efficiency ."

IV-characteristic for the current best four-junction solar cell under AM1.5d ASTM G173-03 spectrum at a concentration of 297 suns. The measurements were carried out at the Fraunhofer ISE CalLab. Credit: Fraunhofer ISE

"This world record increasing our efficiency level by more than 1 point in less than 4 months demonstrates the extreme potential of our four-junction solar cell design which relies on Soitec bonding techniques and expertise," says André-Jacques Auberton-Hervé, Soitec's Chairman and CEO. "It confirms the acceleration of the roadmap towards higher efficiencies which represents a key contributor to competitiveness of our own CPV systems. We are very proud of this achievement, a demonstration of a very successful collaboration."

"This new record value reinforces the credibility of the direct semiconductor bonding approaches that is developed in the frame of our collaboration with Soitec and Fraunhofer ISE. We are very proud of this new result, confirming the broad path that exists in solar technologies for advanced III-V semiconductor processing," said Leti CEO Laurent Malier.

External Quantum Efficiency of the four-junction solar cell. The measurement was performed at the Fraunhofer ISE CalLab. Credit: Fraunhofer ISE

Concentrator modules are produced by Soitec (started in 2005 under the name Concentrix Solar, a spin-off of Fraunhofer ISE). This particularly efficient technology is employed in solar located in sun-rich regions with a high percentage of direct radiation. Presently Soitec has CPV installations in 18 different countries including Italy, France, South Africa and California.

Explore further: Building a better battery

Related Stories

'Cleaning' boosts solar cell efficiency

Sep 13, 2013

Energy losses in nanowire solar cell can be significantly reduced by 'cleaning' the surface of the cells with a special etching method. This has been shown by researchers at Eindhoven University of Technology ...

Recommended for you

Are electric cars greener? Depends on where you live

13 hours ago

Long thought a thing of the future, electric cars are becoming mainstream. Sales in the United States of plug-in, electric vehicles nearly doubled last year. Credible forecasts see the number rising within ...

Building a better battery

14 hours ago

Imagine an electric car with the range of a Tesla Model S - 265 miles - but at one-fifth the $70,000 price of the luxury sedan. Or a battery able to provide many times more energy than today's technology ...

Researchers find way to turn sawdust into gasoline

19 hours ago

Researchers at KU Leuven's Centre for Surface Chemistry and Catalysis have successfully converted sawdust into building blocks for gasoline. Using a new chemical process, they were able to convert the cellulose ...

Nanodot team aims to charge phones in less than a minute

23 hours ago

The world of smartphone users, which is a very large base indeed, is ripe for better battery solutions and an Israel-based company has an attractive solution in store, in the form of nanodot batteries that ...

User comments : 32

Adjust slider to filter visible comments by rank

Display comments: newest first

packrat
2.5 / 5 (13) Sep 24, 2013
Now will someone working on these things come out with one that uses one sun and gets 44.7 percent efficiency with that please. I can't put a bunch of big magnifying lenses and red hot solar cells on top of my house. I don't think the insurance company would really appreciate it.
ekim
2 / 5 (4) Sep 24, 2013
Now will someone working on these things come out with one that uses one sun and gets 44.7 percent efficiency with that please. I can't put a bunch of big magnifying lenses and red hot solar cells on top of my house. I don't think the insurance company would really appreciate it.

Do you have light bulbs in your house?
packrat
1.8 / 5 (10) Sep 24, 2013
Of course and every single one is contained in a metal housing far enough away from anything flammable that it's very unlikely to catch anything on fire. The problem I've found is that insurance companies don't always have realistic logical reasons for what they will and won't insure.
Actually as far as I can tell it wouldn't take a very big array with those cells to supply my needs and it could probably be mounted on a ground frame. Getting a landlord to go along with the idea is another story though. I've already been through that before.
italba
5 / 5 (3) Sep 25, 2013
This technology is not for home solar plants! These cells costs too much, concentrated photovoltaics needs sun-following mechanisms, which in turns needs specialized engineers to install and mantain. Home solar plants have cheap amorphous or multicrystalline cells that can give 20 or 25% efficiency, are built to be installed in a fixed position, usually over the roof, and needs no maintenance but cleaning. Your insurance company can sleep peacefully.
gotkb
2.3 / 5 (3) Sep 25, 2013
I'm not just responding to educate the nieve about what the point of concentrating is- and frankly anyone who posts should of thought about it sufficiently to understand mirrors and len's are cheap, the issue in fact IS NOT EFFICIENCY!

The issue is cost. '50%' as a target DOES NOT APPLY FOR CONCENTRATING! What matters is the amount of wattage these cells are puttting out- it's tiny, and a lot per square inch, but you get to dump so much light into it that it's cost AND efficiency matter less then how many sun's you can harness.

That means MORE not FEWER is BETTER! If you double the amount of energy it can generate it could be OK if you tripled the amount of sun you need to do that! What matters is how hot it can get, how hard it is to keep cool- not so much if it's under 30 or over 50 percent energy removing for 'light' directed at it. Not for 'wings' or orbiting of course- but for terrestrial use of course! (as a child I fooled around with dozens of sun's using 144 inch mirror
antialias_physorg
3.7 / 5 (3) Sep 25, 2013
Now will someone working on these things come out with one that uses one sun and gets 44.7 percent efficiency with that please.

These would be enormously expensive - as with one sun you'd need material to cover the entire area where you want to catch sunlight from.

Triple (or quadruple) juncton cells need many steps during manufacture and also use rather expensive matreials (at least when compared to normal solar cells or thin film ones)

But, of course, there are cases where cost doesn't matter. E.g. for sattelites Watt/kg is the figure of merit. Any weight saved means less launch cost (or more payload).
These kinds of cells are also very attractive for large powerplants, as maintenance/replacement is far simpler for small cells than for huge panels.

sirchick
5 / 5 (2) Sep 25, 2013
Are they are ever going to be affordable to buy to put on our home roofs? Also how long will it stay at that efficiency? Doesn't it degrade?

Unless we can all start buying them to put on our roofs and in our back yards they won't ever dominate the clean energy world in my view.
antialias_physorg
5 / 5 (4) Sep 25, 2013
As you can see from the article: You only need 1/300th the size of the area you want to cover. So the photovolatic material - expensive as it may be - is probably not the major cost factor for such a system.
It's going to be the lenses, the cooling apparatus, and the mechanism for keeping the lenses focussed on the PV cell. Each of those isn't very expensive, so this might come out to be cost competitive (moreso the larger your installation)
bearly
3 / 5 (4) Sep 25, 2013
We continually read about solar cell advances but we never get the chance to buy a high efficiancy product that will work for the average consumer at a reasonable cost.
RealScience
5 / 5 (3) Sep 25, 2013
@bearly - It is frustrating, but the path from R&D to affordable product is very long and risky. However you can now buy dollar-per-Watt 15%-20% efficient panels based on the cumulative R&D of the past few decades, so eventually some R&D does show up in products.

@Sirchick:
Multi-junction cells were designed for space (lots of UV), and hence are very durable as long as kept dry (sealed), so efficiency should stay high for decades.

Do you have your own well? Septic? Generator? These exist, but most people depend on centralized services for these basic services, so why should solar electricity be dominated by users' own rooftops rather than by utility companies?
As much as I am a DIY guy (with own well, septic, generator, garden, wood-lot, etc.) I am aware that that is a personal preference and not the answer for most people.
sirchick
not rated yet Sep 25, 2013
Do you have your own well? Septic? Generator? These exist, but most people depend on centralized services for these basic services, so why should solar electricity be dominated by users' own rooftops rather than by utility companies?
As much as I am a DIY guy (with own well, septic, generator, garden, wood-lot, etc.) I am aware that that is a personal preference and not the answer for most people.


Well if the panels were owned by a company im sure they would come up with ways to make me keep paying more and more £££ every year than i should be, compared with if i just bought them myself.
RealScience
5 / 5 (1) Sep 25, 2013
@sirchick - they would likely put the panels where they get better sun and clean them more often, buy in bulk and install in bulk to get lower costs, pool those panels' power with other panels to give you more power when you need it, and find a use for your excess when you have excess. Even after they charge a significant markup on the power it would likely still cost you less.
(For reference, as much as I like having my own well, it costs me more per decade than it would to just turn on a tap in town and pay for the water.)
antialias_physorg
5 / 5 (6) Sep 26, 2013
We continually read about solar cell advances but we never get the chance to buy a high efficiancy product

You can buy 30% efficient solar cells (single junction GaAs cells, still rather expensive).
When looking at the history of solar cell research:
http://en.wikiped...%29a.jpg
you'll notice that it's not that long ago when these were peak values in research prototypes (roughly 12 years ago).
It just takes some time to go from the lab to market.
To a company efficiency alone isn't the deciding factor. It's how well the type of cell can be manufactured in bulk using existing machines.
Companies don't like to invest in new machines. It's not good for profit.
They also don't like to invest in new products while the old ones are still a cash cow. They'd destroy their own market.

Remember: Capitalism is not about providing the best product. It's about making the most profit.
Ober
5 / 5 (1) Sep 26, 2013
I think people here need to look at http://phys.org/n...tml#nRlv to see that FRESNEL lenses are used to concentrate (SUN multiplier) light to make the panels. So you use a tiny solar panel, with a frame around it and a Fresnel lens sat on top. No need for mirrors everywhere!!!
Aranrhod
not rated yet Sep 26, 2013
One issue rarely mentioned with multijunction cells is that it is absolutely critical to keep the incident light spectrum constant and equal to the one the cells are designed against. Even the passage of the sun from the zenith to nearer the horizon can change the incident light enough to cause a remarkable drop in the cell efficiency. So 44.7% is a splendid achievement but not a figure that you'd often get in the real world. Also, fresnel lenses will not be achromatic and will focus different parts of the spectrum at different locations in space, in effect altering the spectral power density of the incident radiation, and this effect would have to be allowed for when designing the precise cut off wavelengths of the individual cells. For spaceborne applications however where you can afford very expensive focussing optics and there are no atmospheric effects, the cells should work admirably well.
VendicarE
2.6 / 5 (5) Sep 26, 2013
Remember: Capitalism is not about providing the best product. It's about making the most profit.

Capitalism is about providing the customer with the worst possible product at the highest possible price through whatever means possible.

RealScience
5 / 5 (2) Sep 26, 2013
@Vedicar:
In capitalism people buy your product because they value it more than their money.
If you have a crappy product, people won;t knowingly buy it, and if they unknowingly buy it they won't be repeat customers and will tell others not to buy it.

So while capitalism isn't perfect, it is far from being about providing crap at high prices and forcing it down peoples' throats.

Capitalism is about proving a product that a significant segment of the market will find attractive at a price that they will find attractive, and ideally having them be happy enough to tell their friends (or at least not being unhappy enough afterward to tell their friends).

The problem is that greedy people screw up capitalism, just as they screw up any system.
kochevnik
1 / 5 (7) Sep 26, 2013
Remember: Capitalism is not about providing the best product. It's about making the most profit.

Capitalism is about providing the customer with the worst possible product at the highest possible price through whatever means possible.
Capitalism would be far better than the kleptocracy the USA now has. Right now the zionist banksters are giving free money to Warren Buffett to buy up anything so rent can be charged on EVERYTHING. People stripped of ownership shed a lot of blood in England and other places. It seems Americans are too fluoridated at the moment but at some threshold point the basic instincts will activate in the worst way

Real capitalism has benefits but it died a while ago
antialias_physorg
5 / 5 (3) Sep 27, 2013
Capitalism is about providing the customer with the worst possible product at the highest possible price through whatever means possible.

I wouldn't go that far (as in your statememn there are two issues to maximize - which isn't possible). If a better quality product can be manufactured at the same price then some other company will manufacture said product and outcompete the other. THAT part of capitalism works (always provided the first company doesn't do any shennanigans like hostile takeovers, protective patent suits, large PR campaigns, and all the other tricks of the trade that undermine the general idea)

However, capitalism is not a method that will automatically lead to better products by itself. specially if the worse (but cheaper to produce) product makes more money. Photovoltaics productino volumes had lagged behind demand for a time. In that timeframe no innovation/improvement was sensible for the manufacturers (from a profit POV).
TheGhostofOtto1923
2 / 5 (5) Sep 27, 2013
These would be enormously expensive
Well they must very cost effective in some applications as there are many CPV plants up and running in many places around the globe.
http://www.soitec...lar-cpv/
TheGhostofOtto1923
1.3 / 5 (4) Sep 27, 2013
This is what a small portion of the soitec panels look like
http://www.greenb...rica.jpg
brt
1 / 5 (5) Sep 27, 2013
44.7% is pretty amazing. coal is around 41%, nuclear is 23%, oil/gas is in the teens. If I were a politician in Arizona, I would be paying close attention to this. Might end up changing the state motto to "the energy state".
brt
1 / 5 (8) Sep 27, 2013
Remember: Capitalism is not about providing the best product. It's about making the most profit.

Capitalism is about providing the customer with the worst possible product at the highest possible price through whatever means possible.



That's a pretty simplistic view. When the iphone 3s came out, it was $600. You can get an iphone 4s for less than $100 now. Some plans give them away for free.

Capitalism is about letting the consumer decide the value of a product. Do you need an iphone 5? hell no. You don't need any smartphone. But there are still a few million people who will wait in line for 24 hours to be the first to have one at the most expensive price it will ever be. Wait six months and the price will drop by 60%.

Your description of capitalism requires people to be undisciplined and stupid. Most people are not.
shavera
3 / 5 (2) Sep 27, 2013
When the iphone 3s came out, it was $600. You can get an iphone 4s for less than $100 now.
whoa now. That's a patently false statement. The phones still cost around $600. You're mixing the cost of the phone vs the out-of-pocket cost when purchased on a plan that subsidizes the cost of the phone (you explicitly note this when you say "some plans give them away for free") That's a wildly apples-oranges comparison.
brt
1.7 / 5 (6) Sep 27, 2013
whoa now. That's a patently false statement.


I guess I should have been more explicit and said that you can get one refurbished, used, or come across the occasional sale price (after rebates too) cost of $100(without a plan) or even free (with a plan). But the underlying idea I was explaining is still the same since back when the 3s was out, it would still cost you $600 despite your plan (even though it was exclusively AT&T at the time).

I guess if we wanted to nitpick details that detracted from the topic, then I could also mention that even with the cost of the phone factored into your plan, it is still cheaper than the previous plans with inferior quality phones.

The intent was not to start a debate over apple products. The intent was to explain that this person's concepts of capitalism require nonexistent assumptions and restrictions on society.
RealScience
5 / 5 (1) Sep 27, 2013
44.7% is pretty amazing. coal is around 41%, nuclear is 23%, oil/gas is in the teens...


@brt - 44.7% is indeed amazing, but that is for the cell itself, and a 'hero cell' at that. By the time it is in a module and wired up to an inverter (including optical losses, cell mismatch and wiring resistance) , the AC efficiency from such cells will be more like 35%.
The best coal may be over 40%, but a lot of coal is still mired in the low-to-mid 30s. In contrast the best natural gas generators have just passed 60%. (But those fossil fuel figures don't include the energy required to extract the fuel, which for natural gas - ~10% and coal ~1.5%).
However the most important points are that we a multi-billion-year supply of sunshine, and that solar has a smaller lifetime environmental footprint than fossil fuels.

And the cost of solar continues to fall rapidly - it is already competitive in some areas.
michael_hollingsworth_184
1 / 5 (6) Sep 27, 2013
You will never see high efficiency solar cells on the open market for the general public. The power companies will not allow it. They will lose too much money. Think I am joking? Do a little research "Spain privatizes sun making it illegal for small consumers to generate energy using solar panels"
antialias_physorg
5 / 5 (4) Sep 28, 2013
You will never see high efficiency solar cells on the open market for the general public.

You do realize that the solar cells you can buy right now were high efficiency solar cells in the lab not so long ago?
sirchick
not rated yet Sep 28, 2013
So what is the reason we don't all jump to get solar cells on our sun facing roofs? Lack of awareness? Lack of people wanting to change their habits of going green?

Not cost effective? I was hoping to see cities using solar panels on their roofs by now but it just hasn't happened here in Uk at least. (Granted we don't get amazing weather but it should still be good enough!)
antialias_physorg
5 / 5 (2) Sep 29, 2013
So what is the reason we don't all jump to get solar cells on our sun facing roofs?

Initial investment. Most people don't have spare cash lying around.

Also, if you rent, then it's not an option for you. For those that own the houses you pay rent for it's often more lucrative to build more houses than to put up PV panels.
meBigGuy
not rated yet Sep 29, 2013
What a complete waste of time!! Why work on achieving 44% efficiency when what we need is 100% efficiency. Scientists can't even set their goals correctly. It's a government conspricy. The scientists are too damn lazy to get it right. Why work on 100% when the government funds them for 44%. And it costs too much.
[sarcasm off]
rwinners
not rated yet Sep 30, 2013
Cost to scale?

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.