Swiss Federal Lab Claims New World Record For Solar Cell Efficiency
Zothecula writes "Scientists based at Empa, the Swiss Federal Laboratories for Materials Science and Technology, have set a new efficiency record for thin-film copper indium gallium (di)selenid (or CIGS) based solar cells on flexible polymer foils, reaching an efficiency of 20.4 percent. This is an increase from a previous record of 18.7 percent set by the team back in 2011."
And yet still horribly inefficient.
Only 20.4%? That's better than a weather man but worse than an average baseball player. Next!
It seems like every couple of months some solar cell breaks a different barrier. A slashdot story from November (http://tech.slashdot.org/story/12/11/03/2010244/solar-panel-breaks-third-of-a-sun-efficiency-barrier) clocked some solar panel as being 33.5% efficient. Are they measuring on different scales or definitions of efficiency or something?
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This will revolutionise electricity generation in such diverse fields as, uh... space craft and... um... space stations.
If you were blocking sigs, you wouldn't have to read this.
I've been hearing these stories about solar cell efficiency improvements for years and years. Same old lab vaporware.
Until you have product for sale, it's just hype.
I feel like I've heard this before:
http://hardware.slashdot.org/story/06/12/06/027228/solar-cell-achieves-40-efficiency
http://tech.slashdot.org/story/12/11/03/2010244/solar-panel-breaks-third-of-a-sun-efficiency-barrier
Do the math on a solar powered car.....
Assume you could cover the entire top surface(s) of a small car with solar panels and let them charge batteries
all day while the car is parked at work. Assume battery charging is 100% efficient:
Panel Area ~4 m^2 (liberal, but I'm trying to make a point)
Panel Efficiency 20.4%
Time in sun 8 hours
Sun angle derate 50%
Solar input ~1kw/m^2
Then the batteries get charged with 1*4*8*0.5*0.204 ==> ~3.26 KWH
A small car engine is rated at ~200 KW (i.e. Ford Focus Spec at 223 KW)
If you average using only 1/4 the available power ===> 50 KW
The saved energy in the battery will move you for 60min*3.26/50 ===> ~4 minutes
So, you run out of juice about the time you hit the on-ramp of the freeway.
The point being, this isn't going to work unless you have more efficient cells, more efficient vehicles, more
solar panel area, or a combination of all three.
Before somebody brings up 40% efficient cells, this efficiency is for a single layer. The 40%+ efficiencies are for so called multiple junction cells which are basically several solar cells stacked on top of one another. This record is for a single layer, for which 20% is really good.
Also, comparisons with petrol engines efficiency are kinda pointless since the advantages and disadvantages of solar is environmental impact and cost respectively. Nobody really cares if it is more or less efficient than petrol. What people are concerned about is environmental impact and cost, which are not easily compared by looking at the efficiency.
For solar cells, for cancer. Just stop promoting these press releases. When it comes to market as a proven technology, then I'll be impressed.
It's the cost that matters more than efficiency. I don't need a 20% efficient panel that costs 10 times what a 10% efficient panel costs. Really I just want some inexpensive but durable panels. Something where I can recoup my costs in 3 or 4 years not a decade or so.
It's all about Storage, Shielding, and Containment. The most egregious flaw in the modern power system is that we have to use it or lose it.
Let me know when you can buy a 1KW panel for $50.
If covering 0.01% of the surface area of the US could supply 7.5% of the electricity, covering 100% of the US would supply 75000% of our power needs (under the unrealistic most optimal conditions you state). A billion square meters is only ~33km*33km, which wouldn't even take up a fraction of one of our major southwestern deserts.
There are 311 million residents, why would you only put down 3 square meters per person? The average middle class home roof is approximately 200 square meters and there's a good deal more roof space for businesses. Obviously there are many constraints and other costs preventing that, but it seems like the most optimal conditions would allow for more than 7.5% in roof space alone. You can fit a billion
And still polysilicon reigns as king. Why? It's because this breakthrough still hasn't changed the most important measure which is cost per watt. From a business and consumer perspective that's what matters.
When they figure out how to reduce the cost per watt of solar, let me know. We need a to reduce the cost of solar energy to at least 1/5th of what it costs now if it's to compete with coal. Even if we figure out how to make solar cells out of newspaper .. the cost of battery/storage for overnight will keep it's cost above that of coal. So for solar to be a success we need two breakthroughs .. first and foremost ... how do we make solar cells cheaply? .. And second, .. how do we make cheap batteries?
Think about it, if you are going to build a power plant .. would you spend 5 to 10 times more on it and get unsubsidized solar or will you save money and build coal? That's the question facing power plant builders.
Was it really record breaking?
http://rsta.royalsocietypublishing.org/content/369/1942/1840/F6.large.jpg
According to this graph they were no where close to breaking the record back in 2011 with 18.7%. I really wish I had a more updated graph but I believe the CIGS were bumped up higher since this graph was produced (back in 8/2010).
Have gnu, will travel.
I know someone with a Rav-4 which she charges from solar panels on the roof of her house.
However, unless there's a serious revolution in battery technology, I don't think the electric car is ever going to be practical.
Likewise, solar panels don't work at night, under trees, or when it's cloudy.
None of those are arguments against developing solar technology. Or wind power. While neither of these can ever totally replace fossil fuel power or nuclear, they make excellent supplements. Solar power is at its peak at the same time demand is at its peak. And every kWh of solar power represents 1-2 lbs of CO2 not released into the atmosphere.
What happened to these guys?
NRL Designs Multi-Junction Solar Cell to Break Efficiency Barrier
by Staff Writers Arlington VA (SPX) Jan 17, 2013
http://www.solardaily.com/reports/NRL_Designs_Multi_Junction_Solar_Cell_to_Break_Efficiency_Barrier_999.html
Schematic diagram of a multi-junction (MJ) solar cell formed from materials lattice-matched to InP and achieving the bandgaps for maximum efficiency.
U.S. Naval Research Laboratory scientists in the Electronics Technology and Science Division, in collaboration with the Imperial College London and MicroLink Devices, Inc., Niles, Ill., have proposed a novel triple-junction solar cell with the potential to break the 50 percent conversion efficiency barrier, which is the current goal in multi-junction photovoltaic development.
"This research has produced a novel, realistically achievable, lattice-matched, multi-junction solar cell design with the potential to break the 50 percent power conversion efficiency mark under concentrated illumination," said Robert Walters, Ph.D., NRL research physicist.
"At present, the world record triple-junction solar cell efficiency is 44 percent under concentration and it is generally accepted that a major technology breakthrough will be required for the efficiency of these cells to increase much further."
In multi-junction (MJ) solar cells, each junction is 'tuned' to different wavelength bands in the solar spectrum to increase efficiency. High bandgap semiconductor material is used to absorb the short wavelength radiation with longer wavelength parts transmitted to subsequent semiconductors.
In theory, an infinite-junction cell could obtain a maximum power conversion percentage of nearly 87 percent. The challenge is to develop a semiconductor material system that can attain a wide range of bandgaps and be grown with high crystalline quality.
By exploring novel semiconductor materials and applying band structure engineering, via strain-balanced quantum wells, the NRL research team has produced a design for a MJ solar cell that can achieve direct band gaps from 0.7 to 1.8 electron volts (eV) with materials that are all lattice-matched to an indium phosphide (InP) substrate.
"Having all lattice-matched materials with this wide range of band gaps is the key to breaking the current world record" adds Walters. "It is well known that materials lattice-matched to InP can achieve band gaps of about 1.4 eV and below, but no ternary alloy semiconductors exist with a higher direct band-gap."
The primary innovation enabling this new path to high efficiency is the identification of InAlAsSb quaternary alloys as a high band gap material layer that can be grown lattice-matched to InP.
Drawing from their experience with Sb-based compounds for detector and laser applications, NRL scientists modeled the band structure of InAlAsSb and showed that this material could potentially achieve a direct band-gap as high as 1.8eV.
With this result, and using a model that includes both radiative and non-radiative recombination, the NRL scientists created a solar cell design that is a potential route to over 50 percent power conversion efficiency under concentrated solar illumination.
Recently awarded a U.S. Department of Energy (DoE), Advanced Research Projects Agency-Energy (ARPA-E) project, NRL scientists, working with MicroLink and Rochester Institute of Technology, Rochester, N.Y., will execute a three year materials and device development program to realize this new solar cell technology.
Through a highly competitive, peer-reviewed proposal process, ARPA-E seeks out transformational, breakthrough technologies that show fundamental technical promise but are too early for private-sector investment.
These projects have the potential to produce game-changing breakthroughs in energy technology, form the foundation for entirely new industries, and to have large commercial impacts.
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The point of this one is that it's a new record for the (potentially) cheap, continuous, roll-to-roll manufacturing process.
A lot of stationary sites are more sensitive to $/installed-watt and $/(installed-watt * ammortized-lifetime). If a process is half as efficient as other alternatives but an eighth as expensive, and there's plenty of surface area to pave (like on a house roof).
What would make it BIG news is if the win is enough to jump it substantially beyond breakeven vs. grid power.
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If the input is virtually inexhaustible (sunlight), it doesn't matter how efficient it is. If you have half the efficiency, just double the solar panel area. Total cost per kW and per kWh becomes is more important. Mind you, the panels *don't* need to be on the car.
Efficiency does matter if area is a concern. A home may have enough roof space for solar PVs to charge a storage system or th power the home but may not have enough for both. Increasing efficiency may allow both to be done.
And that is if there is a battery bank big enough to allow an EV, Electric Vehicle, to have it's own battery system be charged over night. Of course with net metering the grid serves as storage during the day so the EV's batteries are charged at night from the grid.
Falcon
Should there be a Law?
The article does not mention sample area (in, say, mm^2). Does anyone know what it is?
There are technical and social problems - and solutions. The direction of power technology has changed, now goes toward cleaner power. Whatever current technologies allow, in time there will be ways to generate clean power competitively. Germany is most likely to get there first. Public and government have reached consensus to get it done, are working on it nonstop, and are way ahead of everyone else, facing problems and solving them. If the US decides to keep depending on old technologies, for whatever reasons, it might have to pay a price for it. Such as being stuck with a massive industrial and technical infrastructure of oil-based equipment and technologies, when it becomes economically, technically and politically obsolete, and a huge burden.
For comparison, photosynthesis (which powers all life on Earth) is less than 1% efficient.
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