Record Setting Solar Cell

At 43.5% efficiency, Solar Junction pulled ahead by 1.2% points in 6 months, where the industry has had an average improvement of .4% per year.


These cells were originally developed to power satellites in space and more recently modified for terrestrial applications.


I got a sample today from the wafer lot that set the world record. It is a triple junction compound semiconductor cell with a lattice-matched 1eV material. What this means is that there are three solar cell regions layered on top of each other, each tuned to a region of the visible light spectrum, and in aggregate harvesting more of the spectrum than other materials sets. Depositing each of these different layers in a crystal lattice despite differences in their inter-atomic distance is a big part of the engineering challenge.

  • Michael Taggart Photography PRO 4y

    Very neat!!!
  • Steve Jurvetson PRO 4y

    Jeff Wallace - this is a CPV (concentrating photo voltaic) cell which is designed to be small and receive a 300x to 1000x concentration of solar flux. It's actually a production unit, and meant to be cost competitive today. This high end of the tech curve is not facing competition from China yet.

    Or as they put it:
    "Concentrating Photovoltaics (CPV) delivers industry-best efficiency by utilizing low-cost optics and precise 2-axis tracking to concentrate light onto the highest-efficiency solar cells. The optics of a CPV system are like a magnifying glass, collecting light and optically projecting it onto a small, highly efficient solar cell. These systems integrate a solar cell that in the case of Solar Junction, deliver efficiencies over 40 percent, resulting in system efficiencies of 28 percent or higher. CPV systems are being deployed due to their ability to produce energy at the lowest cost of energy in regions of high solar resource.
    By comparison flat panel modules, including silicon and thin films, vary in efficiency, but are based upon the cell technology that ranging from less than 10 percent to an absolute maximum of 22%. Best available cells, in a panel provide approximately 17% efficiency.
    CPV’s path to grid parity and beyond (equivalent cost of energy versus existing fossil fuel sources) is driven by constant improvement in cell efficiencies."
  • Chucil 4y

    Thank you for sharing.

    Are they interested in making portable unit and providing to our troops in Afghanistan?
  • solerena 4y

    Very beautiful, efficient and elegant way:) wish humans could consume light instead of food:)
  • flytrue2 4y

    43.5% efficiency is better than the thermal efficiency of nuclear reactors which are arguably the next best option and typically range between 33-37%.*.

    Coupled with recent advances in semi-solid flow cell battery technology solar power suddenly becomes immensely practical.
  • Happy Tinfoil Cat PRO 4y

    I had the idea to concentrate light onto one of the space type of solar cells, years ago. Been looking for a robust way to limit the amount of light during full sunlight so the thing can be maximized at a lower light level. The cooling mechanism (probably some kind of vapor chamber) could be used to generate more power and hot water. Lately, I've been curious if the Edison effect could be used in conjunction with or place of the solar cell. Photon-enhanced thermionic emission is supposed to be able to reach 60% efficiency. I'm glad to see that CPV are a reality.
  • Tomi Tapio K 4y

    Cool! But large very-low-cost ones might be the better way.
  • dave halliday PRO 4y

    I think in the "50's" we were all going to cook our dinner with a "solar oven"...

    Also,as a Luddite,I wonder if passive solar heating of some mass (water,sand etc) would not ultimately make economic sense...more than a 20,000$ solar panel and a15,000$ battery system..
    Or (for example) maybe storing "energy" by simply pumping a bunch of water up a 200 foot height....and then running it back down a turbine when electricity needed......
    I wonder about steam engines (turbines) on biomass etc
  • Happy Tinfoil Cat PRO 4y

    dave halliday The part about "300x to 1000x concentration of solar flux" means having to use 1/300th to 1/1000th the silicon area and since the silicon is the driving cost factor, this tech should mean a drastic drop in cost per watt. Even if the cost of the more efficient cell is 10X we could see up to a 99% cost reduction.

    Lead acid batteries are passe'. Water towers are too ugly. Perhaps an underground flywheel. The new solid state batteries last far longer, don't have toxic chemicals and are generally much safer.
  • Jason McDonald PRO 4y

    I use LED grow lights for my house plants during the winter. They are tailored to the active region of the visible spectrum for chlorophyll. A friend of mine made the comment that a very efficient solar panel and LED system might input sunlight and output more useable light for plants then contained in the original solar radiation. Im sure it would be cost prohibitive on an agricultural scale but it sure would be cool to have a 'super green' greenhouse in backyard.
  • dave halliday PRO 4y

    I would be surprised if any man made light (LED or otherwise) could be better for plants than the real stuff.....
    They have had a billion years to optimize use of its spectrum...
    But perhaps I am wrong about this...
  • Lars Plougmann PRO 4y

    Dave, chlorophyll has evolved to a local optimum in the light spectrum. Theoretically, plants with black leaves could extract more energy by absorbing light across the visible spectrum.
  • dave halliday PRO 4y

    Hmmm....I was wondering....(after I wrote that)
    but why are leaves green 98% of the time...?
    I see your point...but cannot believe that nature is missing something..
    The chemistry of photosynthesis a bit fuzzy for me currently...but its hard to think plants have not optimized it somehow..

    Anyways...lets just say I am talking through my hat here,as usual..:)
    A quick Google session later;
    I think the point with plants is they must realize that high QE of energy capture is not as important as overall cost...So its true they "specialize" in certain frequencies...hence the green color..
    They also focus on structure and leaf pattern etc..(which we are studying now with a view to duplicating in solar arrays)
    So maybe they are telling us to go lower tech and bigger scale with solar...!
  • Steve Jurvetson PRO 4y

    Consider the microbes of the sea. They have evolved for longer than land based plants, and they have rhodopsins exquistley tuned to wavelength, but not broad spectrum. They sort by various depths and absorb light ideally for the available light at that depth, which is already filtered by water depth and by the microbes above.

    So as a consortia, they operate like a multi-junction PV cell.
  • Jim Rees 4y

    The solar flux is around 1Kw/m2, so 1000x concentration would mean a kilowatt on a chip 3cm square. Makes those Xeon chips almost seem miserly. Half of that would go into moving electrons, but the other 500 watts would have to be dissipated somehow. You'd have the equivalent of a hair dryer blowing out the back side. You could scale down and just build more of them, but the heat flux per unit area remains the same. I think you would need liquid cooling. Cool stuff, but is it really practical?

    Solar panels are running aroung $5-7 a watt retail on Amazon, so if you could build one of these a meter square (aperture size) and sell it for $2500 you'd be in good shape. Again using a Xeon chip for comparison, that seems doable, even after adding the collector, sun tracker, and cooling system. But only in quantity.
  • Happy Tinfoil Cat PRO 4y

    Heat is a bonus. Because it is concentrated you have a larger temperature differential which makes using the energy easier. That excess heat can be used directly or converted to more electricity.
  • Jeff Wallace 4y

    There aught to be a way to put all of that excess heat into something useful if designed properly? perhaps a hotdog cooker ;-)
  • Devendrra 4y

    Have you wondered that you can use calculators without batteries? In this age of technological revolution where saving energy and using renewable sources of energy are stressed, it is indeed possible to save energy if you use solar powered products. Not only they are environment friendly but they have many more advantages to them. powered products such as solar calculators, watches, radio are already popular in the existing market.
  • Steve Jurvetson PRO 4y

    a new category - "Duh! Spam"
  • dave halliday PRO 4y

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Taken on September 14, 2011
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