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Power Science Technology

Researchers Solve Scientific Puzzle That Could Improve Solar Panel Efficiency (phys.org) 170

New solar panels created from a semiconducting material called cadmium telluride (CdTe) "have been found to produce electricity at lower costs than silicon panels and there has been a dramatic gain in efficiency brought about by adding an element called selenium to the cadmium telluride," reports Phys.Org. "Until now, it was not well understood why selenium increases efficiency but thanks to Tom Fiducia, a Ph.D. Research Student in the Center for Renewable Energy Systems Technology (CREST), and an international team of researchers, the puzzle has been solved." From the report: Their paper, titled "Understanding the role of selenium in defect passivation for highly efficient selenium-alloyed cadmium telluride solar cells," has revealed that selenium works by overcoming the effect of harmful, atomic-scale defects in CdTe panels. This explains the increase of efficiency as electrons (subatomic particles that carry electricity), which are generated when sunlight hits the solar panel, are less likely to be trapped and lost at the defects. This increases the amount of power extracted.

Tom, who is the lead author of the paper, says the team discovered this "unexpected" behavior by measuring how much light is emitted from selenium-containing panels. As selenium is not evenly distributed across the panels, they compared the 'luminescence' emitted from areas where there was little-to-no selenium present and areas where the selenium was very concentrated. Tom explained: "While it seems counter intuitive, good solar cell material that is defect-free is very efficient at emitting light, and so luminesces strongly. We mapped the luminescence emitted from a selenium-containing solar cell at a resolution of around 1/10,000th of a millimeter and compared it to a similarly high-resolution map of the selenium concentration taken on the exact same area of the cell. It is strikingly obvious when you see the data that selenium-rich regions luminesce much more brightly than the pure cadmium telluride, and the effect is remarkably strong."
The new-found knowledge could be used to increase the efficiency of cadmium telluride solar panels even further, says Tom. "For instance, this could be by simply increasing the amount of selenium in the devices or altering its distributions within the cell."
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Researchers Solve Scientific Puzzle That Could Improve Solar Panel Efficiency

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  • by Anonymous Coward on Wednesday May 15, 2019 @03:10AM (#58594718)

    I recently looked at wholesale prices of solar cells and it can be as low as 14 cents per Watt. The rest of the panel - support and protection also adds to the cost, but it makes DIY panels made from second hand wooden window frames quite worth the effort.

    • ...but it makes DIY panels made from second hand wooden window frames quite worth the effort.

      Look, I'm part Scottish with possible Austrian crypto-Jew in my blood so I know all about trying to save money... at least get yourself some fucking 1x2's so your working dimensions aren't limited to your used, dry-rotted windows... and learn some perspective; if you're too cheap, you'll end up 'stepping over twenties to pick up pennies.'

      • by ctilsie242 ( 4841247 ) on Wednesday May 15, 2019 @10:28AM (#58595920)

        To me, there is "penny wise, but pound foolish." From years of doing stuff with RVs, solar panels are a one time expense. Either you want the best panels you can to cover the little square footage you have available, or you want a lot of inexpensive panels covering the roof of a larger rig. Because solar panels are installed once and that's it, price savings on the panels themselves can cost a lot more in the long run, just due to the long service life of panels.

        Panels tend to not be the expensive part. Wiring, MPPT converters, inverters, and batteries are the expensive parts, and the stuff that breaks.

  • electrons (subatomic particles that carry electricity),

    Everyday that I learn something new is a good day. But the day I learned the role of electrons was in fourth grade which was thirty nine fucking years ago.
    Does any editor actually read it before approving a post's content these days? Thanks anyway for causing me to count how many years passed since elementary school...

    • While I agree /. editors leave a little something to be desired that's how Loughborough University wrote the submission to Phys.org - believe it or not!
      • I can believe such a poor choice of introduction can come from an academic person, especially from a sience department. But this is what editors are here to filter :)
    • Given the "layers of abstraction" approach taught to many developers, I'm afraid I'd be unsurprised if a few of them really didn't understand enough physics to realize that electricity is normally carried by electrons.

      • by PPH ( 736903 )

        Electricity is carried by holes. Electrons are going the wrong way.

        • Oh, dear. If we're gong that way, elecricity is carried by electrical charge. The electricity in nerves is normally carried by ion transfer.

        • :D Thanks
          I remember a poor electronics instructor from a classroom in the last century, who was on the verge of pulling out his a few remaining hairs out; While we were deliberately "not understanding" why a P/N junction does not cause all holes and electrons rushing towards each other destroy semiconductor properties of the whole diode 3:) After all one element has extra electrons, and other need those electrons in order to fill holes and there is a current that carries electrons :)
          "Sir our (more experie
    • by PPH ( 736903 )

      electrons (subatomic particles that carry electricity), which are generated

      I'm surprised that nobody picked up on the 'electrons are generated' part. They are freed, not generated. Which would be quite a feat of particle physics to pull off in a PV panel.

  • by Anonymous Coward

    Cadmium... a highly toxic heavy metal that causes cancer and other diseases... lets mass produce a fragile, limited life-span product containing the stuff and distribute it over hundreds of thousands of square Kms of earth's surface.

    What could go wrong?

    • Cadmium... a highly toxic heavy metal that causes cancer and other diseases...

      Yes... when inhaled or ingested. Do you think we're going to burn or eat solar cells?

      limited life-span product

      25 years is now considered a limited life-span? I mean, they still work at 80% efficiency after that but that's when solar cells are "end of life".

      • Yes... when inhaled or ingested. Do you think we're going to burn or eat solar cells?

        If the houses that have them on their roofs burn down, yes.

        (not to say that's intended, but it should be a concern with houses that commonly burn down)

    • Comment removed based on user account deletion
  • by thesjaakspoiler ( 4782965 ) on Wednesday May 15, 2019 @05:47AM (#58595090)
    we have to deal later with. =/
    • Toxicity of cadmium is an environmental concern we have to deal later with. =/

      Yes, inhaling and ingesting cadmium is bad. Do you think we're going to burn or eat solar cells?

      • by CrimsonAvenger ( 580665 ) on Wednesday May 15, 2019 @07:44AM (#58595318)

        Yes, inhaling and ingesting cadmium is bad. Do you think we're going to burn or eat solar cells?

        Houses catch fire from time to time.

        It's just barely possible that a house with solar cells made with cadmium might do so one of these days.

        Which means that it's just barely possible that inhaling cadmium might be an issue by and by.

        If we apply the Nuclear Power Rule (even one death is too many), then the possibility of a death should preclude the use of the stuff.

        That said, this stuff might be very useful in space.

        Or Third World countries with way fewer lawyers chasing ambulances than we have....

        • If we apply the Nuclear Power Rule (even one death is too many), then the possibility of a death should preclude the use of the stuff.

          I get your point but has the "Nuclear Power Rule" stopped chemical spills in the US?
          What about explosions on off shore oil rigs or at refineries?
          How about trains hauling chemicals that derail and catch fire?
          etc, etc...

      • The main concern would be if cadmium can leach out of the solar cells over time and if the accumulation is dangerous. If it leaches out, then it can get into the water system. If the numbers are really low then it is a lesser concern.
      • by Foresto ( 127767 )

        "Do you think we're going to burn or eat solar cells?"

        I think we will. Buildings catch fire. Demolition waste ends up in garbage sites. Garbage is sometimes burned. Garbage is also exposed to rain, which carries particles into both surface and ground water. (Relatedly, now that we are looking for them, we know that plastics have found their way into our drinking water supplies.) So, I think the answer is yes.

      • by Foresto ( 127767 )

        "Do you think we're going to burn or eat solar cells?"

        I think we will. Buildings catch fire. Demolition waste ends up in garbage sites. Garbage is sometimes burned. Garbage is also exposed to rain, which carries particles into both surface and ground water. (Relatedly, now that we are looking for them, we know that plastics have found their way into our drinking water supplies.)

        So, I think the answer is yes. We probably will burn and eat solar cells.

    • by zoefff ( 61970 )

      https://en.wikipedia.org/wiki/Cadmium_telluride#Toxicology_assessment [wikipedia.org]
      Apparently that is not too much of a concern.

      Chloride can be nasty, but is widely used in combination with Na

  • Unless there's enough cadmium, tellurium, and selenium to actually facilitate putting CdTeSe panels on every rooftop, this is just another in a very VERY long line of cell-efficiency dick measuring contests.

    • by Anonymous Coward on Wednesday May 15, 2019 @08:04AM (#58595374)

      The quantities needed are fairly negligible compared to the amount of Cd, Te and Se ending up in copper, zinc and lead slags. So I don't think we have to worry too much about that. The recent studies running scare campaigns about this have used very flawed methods and don't understand primary metal supply chains very well (how could we possibly produce 3 times current production ?!?!?!? actually relatively easily, as for by-product metals it's largely a matter of increasing recovery from existing industrial waste streams rather than a lack of geologic availability).

      • by macraig ( 621737 )

        My allusion was that for too long there has been a disproportionate focus on panel efficiency rather than panel cost, which is the single largest barrier to widespread usage. If I had a quarter for every breathless announcement of increased cell efficiency I've read in the last 15 years, I could take a very luxurious cruise. I took note of the claimed cost reduction here, being so out of character for most such announcements, but it's moot if there's no supply chain to back it up. Let's hope you're right

        • My allusion was that for too long there has been a disproportionate focus on panel efficiency rather than panel cost, which is the single largest barrier to widespread usage. If I had a quarter for every breathless announcement of increased cell efficiency I've read in the last 15 years, I could take a very luxurious cruise. I took note of the claimed cost reduction here, being so out of character for most such announcements, but it's moot if there's no supply chain to back it up. Let's hope you're right.

          The efficiency of PV systems has doubled since the mid 90's and the cost has dropped from by a full two thirds. It's the fall in prices that has contributed just as much as the efficiency increase to making PV systems so competitive.

    • by ledow ( 319597 )

      As ever... until I can buy it, until I can hold in my hands a solar panel of the alleged efficiency, then it's all just hot air.

      Battery capacity. Solar efficiency. ICE cleanliness. Teleporters. Affordable 3D printers that'll use any material.

      All hot air. Every week there's another paper and another experiment and another breakthrough.

      I can still only buy lead-acid, alkaline, NiCd, NiMH, Li-Ion and Li-poly, though.

      And those technologies still don't have anywhere near a decent capacity increase in consum

      • by macraig ( 621737 )

        I share the same sentiments. This is all just academic dick-measuring and career positioning, and our hopes are being dragged along for the ride. It's the aftermath of Apollo 11 all over again.

      • Still, today, I can't find a single AA battery on Amazon that beats that capacity, using any technology.

        According to the data sheet [energizer.com], Energizer's L91 AA lithium cells are rated for 3500 mAh. Not rechargable, though, and if you pull a lot of current (1A), they drop down closer to 3000 mAh.

      • by epine ( 68316 )

        As ever... until I can buy it, until I can hold in my hands a solar panel of the alleged efficiency, then it's all just hot air.

        The flip side of this is that everything you now hold in your grubby little hands was somebody else's hot air, once upon a time.

        IBM "pixie dust" breaks hard drive barrier [cnet.com] — 2 January 2002

        Technically called antiferromagnetically coupled (AFC) media and informally referred to as "pixie dust" at IBM, the innovation introduces a thin layer of the element ruthenium onto

    • CdTe cells are already quite wide spread.
      And you can be assured the planet is not running out of metals or other elements soon ...

      • by macraig ( 621737 )

        I am not assured of that, and CdTE panels already being widespread does nothing if not increase the concern. How much of those elements now is locked away permanently in cells that will likely never see the inside of an appropriate recycling plant?

        Not running out of metals? You'll change your tune when someone steals the catalytic converter from your SUV or the plumbing and wiring from under your house.

        • From my limited interactions with the solar cell industry, the amount is fractions of a percentage. As for recycling them, considering that it takes 2577F(1414C) to melt silicon just to free up the cadmium, it is probably safe to assume that the very little amount of these metals you get and the huge amount of silicon makes it less likely the target of thieves. Other metals like copper is easier to get as stealing wire for example yields lots of copper.
  • Stepping away from the current argument raging over this article already....

    I say good for them! I'm not a "greenie", and I believe that we should use all available and commercially viable forms of energy, whether that is coal, oil, nuke, hydro, wind, solar, sodium reactors, etc. If it works, and is economically affordable, then go for it!

    Now, having said that, I have no issues at all transitioning away from hydrocarbon based energy sources to "green" ones, as long as they are commercially and economicall

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