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Nanopillar Solar May Cost 10x Less Than Silicon

Al writes "A team of researchers from the University of California, Berkeley, have developed a new kind of flexible solar cell that could be far cheaper to make than conventional silicon photovoltaics. The cells consist of an array of 500-nanometer-high cadmium sulfide pillars printed on top of an aluminum foil — the material surrounding the pillars absorbs light and releases electrons, while the pillars themselves transport the electrons to an electrical circuit. The closely packed pillars trap light between them, helping the surrounding material absorb more. This means the electrons also have a very short distance to travel through the pillars, so there are fewer chances of their getting trapped at defects and its possible to use low-quality, less expensive materials. '"You won't know the cost until you do this using a roll-to-roll process," says lead researchers Ali Javey. "But if you can do it, the cost could be 10 times less than what's used to make [crystalline] silicon panels."'"

29 of 199 comments (clear)

  1. That title makes me cringe. by albedoa · · Score: 4, Insightful

    "10x Less"? Is that like "twice as cold"?

    1. Re:That title makes me cringe. by ScentCone · · Score: 3, Interesting

      Maddening, isn't it?

      The only way "ten times less" makes any sense is when you're talking about three costs.

      A is expensive! B is much more efficient, and costs half as much. C is even more efficient than B - ten times less expensive than A, compared to B.

      Otherwise, when you only have two things to compare to one another, just say that "B is one tenth the cost of A."

      Why is this so damn hard for people to process? If they could just think about it, they'd save me ten times the typing.

      --
      Don't disappoint your bird dog. Go to the range.
    2. Re:That title makes me cringe. by The+End+Of+Days · · Score: 4, Funny

      But if you go making reasonable assumptions in a socially correct manner then you can't express your nerd rage properly.

    3. Re:That title makes me cringe. by nutshell42 · · Score: 3, Funny

      I could care less about people not saying what they mean out of sheer laziness and/or stupidity.

      --
      Don't think of it as a flame---it's more like an argument that does 3d6 fire damage
  2. I am f tired reading about cheap solar panals by Anonymous Coward · · Score: 5, Insightful

    for last 5 years same shit gets posted over and over again - Cheap solar panals
    5 years later - in some cases panels went up in price

    1. Re:I am f tired reading about cheap solar panals by vertinox · · Score: 3, Insightful

      for last 5 years same shit gets posted over and over again - Cheap solar panals

      Umm... No. The price to produce them has gone down and is in fact the lowest it has ever been.

      It is just that the demand is outstripping supply so economics is causing a price increase.

      --
      "I am the king of the Romans, and am superior to rules of grammar!"
      -Sigismund, Holy Roman Emperor (1368-1437)
    2. Re:I am f tired reading about cheap solar panals by mcrbids · · Score: 4, Informative

      for last 5 years same shit gets posted over and over again - Cheap solar panals
      5 years later - in some cases panels went up in price

      Whine whine whine. It's been going on for much longer than 5 years. When I was in 5th grade, I did a report on PV electricity, and I read numerous reports that PV panels could be much cheaper soon.

      Truth is, all those funky predictions were right. Solar power HAS been dropping very steadily and very predictably all along in its own version of Moore's law - PV prices drop about 6% per year per watt, cutting in half every 10.5 years. It's not dropping like a stone, but it's very predictable and very steady.

      What's been going on the last 5 years? Simple: supply and demand. For many reasons, people have become wary of using fossil fuels and are willing to invest more into solar, causing a sudden, worldwide deficiency in production capacity. Low-cost production companies like Nano-Solar are ramping up production literally as fast as they are physically able.

      For example, Nano-Solar has, for all intents and purposes, unlimited funding, and has already sold out several years worth of production, even that which is not actually happening yet. They are buying huge rafts of warehouse space in the Bay Area, in what used to be automotive manufacturing areas.

      So the laws of supply and demand are working their magic, even though the response isn't instant. Your children will bask in a society powered by cheap solar electricity that you are funding right now, just as you benefit from the electrical power infrastructure built by your parents.

      --
      I have no problem with your religion until you decide it's reason to deprive others of the truth.
  3. Cadmium ... by Anonymous Coward · · Score: 4, Interesting

    Look at the toxicity of cadmium and all the environmental regulations that come with it. It's regulated to 1/10th the level of mercury in the EU RoHS (Reduction of Hazardous Substances in Electronics) legislation.

    1. Re:Cadmium ... by StellarFury · · Score: 3, Insightful

      Because you first get the technology to work with whatever chemicals you can.

      Then you find environmentally-safe alternatives.

  4. Creation of Electrons by Bucky340 · · Score: 3, Funny

    "the material surrounding the pillars absorbs light and creates electrons."

    Wow, creation Ex Nihilo or from other subatomic particles? That is powerful technology.

  5. Based on recent history... by OpenSourced · · Score: 3, Insightful

    Don't tell me. It'll be ready for mass production in 3 to 5 years. Somehow, I seem to remember stories like this from more than five years ago, and still, nothing happens and the solar cells are more or less the same as always.

    --
    Rome taught me patience and assiduous application to detail. Virtues which temper the boldness of great, general views.
    1. Re:Based on recent history... by Marcika · · Score: 5, Informative

      Don't tell me. It'll be ready for mass production in 3 to 5 years. Somehow, I seem to remember stories like this from more than five years ago, and still, nothing happens and the solar cells are more or less the same as always.

      Don't be a universal cynic, inform yourself instead. Look up Nanosolar and First Solar on Wikipedia, and you'll see that they have been already mass-producing panels at one-third of the price of crystalline silicon panels for a year or two.

      "Nothing happens" is only true if you close your eyes to all the things that actually do happen.

    2. Re:Based on recent history... by Spoke · · Score: 4, Informative

      Surprise, there are already companies that are producing thin-film solar panels for less than $1/watt.

      The problem is that demand is so high for these inexpensive cells that at least for Nanosolar, you can't even buy them unless you are buying tons and tons of them. That leaves First Solar and those panels get significantly marked up because of the lack of competition at the low end of the market.

      That said, wholesale prices of traditional silicon panels are around $3/watt and as an end user you can get them for slightly above that if you shop around.

      But once the system is installed you're looking at a minimum of $6/watt currently. So while the panels are still the most expensive part of the system, pretty soon the other components (inverter, mounting hardware, wiring, labor) will exceed the cost of the panels.

      We're getting very close to the point where solar systems make financial sense for just about everyone. It already makes sense for any high electricity users who pay a premium for electricity. We'll probably see solar system pricing continue to drop over the next couple years as manufacturing capacity continues to come online.

  6. Conspiracy buffs rejoice! by ArhcAngel · · Score: 3, Funny

    Once you install these on your roof you will only need to wear your tinfoil hat when you are outdoors.

    --
    "A person is smart. People are dumb, panicky dangerous animals and you know it." - K
  7. "may" cost less by Geoffrey.landis · · Score: 3, Insightful

    Nanopillar Solar May Cost 10x Less Than Silicon

    ...and then, it may not.

    --
    http://www.geoffreylandis.com
  8. Re:Wait a second by Nexus7 · · Score: 5, Insightful

    This may have made it cheaper with this innovation, but what if no one wants it because power from coal is cheaper, more reliable, plentiful, and so on? Cap 'n Trade would change the market (not technology) to make this new technology (and others) more competitive in the marketplace. That's the idea anyway.

  9. Re:Great news! by dogolopee · · Score: 5, Interesting

    Just think one day we can grow massive "pillars" in the earth, and these "pillars" can sequester carbon and be powered by the sun as they grow. Then as they reach a certain height and are no longer as efficient as they once were, we can take them down and use them as fuel. We can then plant new pillars to grow and use the by products from old burnt "pillars" to help the new ones grow. Perhaps then if we properly manage these "pillar farms" and modify the "pillars" just right we can have them absorb more carbon from the air than they release when burned for fuel.

  10. Re:Oh Yeah!!! by Jeremi · · Score: 5, Insightful

    If it really was that good, then why would they talk about it after they prove the concept first...

    You're absolutely right. From now on, all scientific research should be kept completely confidential until they have developed a product that is ready to ship. After all, there's no value to scientific knowledge; the only things worth talking about are consumer products.

    Stupid git.

    --


    I don't care if it's 90,000 hectares. That lake was not my doing.
  11. Re:Great news! by DoofusOfDeath · · Score: 3, Funny

    Just think one day we can grow massive "pillars" in the earth, and these "pillars" can sequester carbon and be powered by the sun as they grow. Then as they reach a certain height and are no longer as efficient as they once were, we can take them down and use them as fuel. We can then plant new pillars to grow and use the by products from old burnt "pillars" to help the new ones grow. Perhaps then if we properly manage these "pillar farms" and modify the "pillars" just right we can have them absorb more carbon from the air than they release when burned for fuel.

    Perhaps, but is that technology "green"?

  12. Low cost until scarcity kicks in.... by macraig · · Score: 3, Interesting

    How plentiful is cadmium relative to silicon? Not so much, right? Isn't cadmium already pretty much spoken-for in other industrial and consumer electronics applications?

    Leave it to engineers not to consider the ugly realities of supply-and-demand economics.

    1. Re:Low cost until scarcity kicks in.... by TheSync · · Score: 5, Informative

      How plentiful is cadmium relative to silicon?

      Worldwide known reserves of Cadmium are about 490,000 metric tons, and production is about 20,000 metric tons/yr. Cadmium is generally recovered as a byproduct from zinc concentrates. Zinc-to-cadmium ratios in typical zinc ores range from 200:1 to 400:1. Estimated world identified resources of cadmium were about 6 million tons, based on identified zinc resources of 1.9 billion tons containing about 0.3% cadmium. The average annual New York dealer price of cadmium metal in 2007 was $7.61 per kilogram ($3.45 per pound).

      The source of the silicon is silica in various natural forms, such as quartzite. Silicon is the second most abundant element (after oxygen) in the crust, making up 25.7% of the crust by mass. Word production of silicon is about 5.7 million metric tons/yr. The price for silicon ranges from $0.66 per pound for 75% ferrosilicon and $1.13 per pound for silicon metal.

    2. Re:Low cost until scarcity kicks in.... by JustinOpinion · · Score: 3, Insightful
      Their device uses a cadmium telluride (CdTe) active layer. Actually the tellurium is the limiting factor since it is even rarer than cadmium. Of course that could change depending on the economics of exploitation and what new sources are discovered. Whether Cd or Te is the limiting factor, devices based on CdTe (including the one in the scientific article) use a CdTe layer only 1 micrometer thick. So a metric ton of raw material would be enough for roughly 171,000 m^2 of solar cells. This gives us 1 GW of power per 66 metric tons. Not great, perhaps, but probably good enough to justify manufacture and distribution.

      Moreover, I don't understand the pessimism of:

      Leave it to engineers not to consider the ugly realities of supply-and-demand economics.

      How else do we consider these ugly realities if not to study available materials, test the limits of what works and what doesn't, build prototypes, publish results, and work towards commercialization... ? Other materials may eventually be used in real devices (either after a period of using the relatively rare Cd and Te, or perhaps well in anticipation of those supply problems). Even if the device, as presented, doesn't mesh up with the realities of current supply-and-demand, it is part of the process of getting from a problem ('we need energy') to economically-viable solutions.

  13. Re:Great news! by JustinOpinion · · Score: 3, Informative

    For those with access, here's the actual paper:
    Fan, Zhiyong, Haleh Razavi, Jae-won Do, Aimee Moriwaki, Onur Ergen, Yu-Lun Chueh, Paul W. Leu, et al. "Three-dimensional nanopillar-array photovoltaics on low-cost and flexible substrates." Nature Materials advanced online publication (July 5, 2009). http://dx.doi.org/10.1038/nmat2493.

    One of the cool things is that this new process results in a flexible photovoltaic. In the paper they show that efficiency is maintained even after repeated bending of the material. Even if the energy collection efficiency is lower than conventional silicon photovoltaics, there are tons of applications for flexible photovoltaics, like having tents coated in the material (both for things like camping, but could also be hugely useful for the military, for temporary tents for disaster relief, and so on...), clothing that generates power, and so on... (Maybe even fanciful things like kites that collect solar and wind power?)

    It's not a commercial device yet (and oftentimes these kinds of lab devices just don't scale to mass production that well), but it's an encouraging step towards more robust solar cells, which would aid in the more widespread deployments of solar energy.

  14. Hard to estimate future cost by nokiator · · Score: 3, Interesting
    The language projecting the cost savings for this new solar technology is somewhat dubious as usual. Even if the developers of this technology have good reason to think that the cadmium sulfide based solar panel technology will cost 1/10th compared to today's cost of developing silicon based solar panels, what happens between now and when they are able to take this technology to mass production in five or more years?

    There is a massive world-wide technology complex driving the optimization of silicon based manufacturing technology. The amount of capital invested into silicon manufacturing process and tools is measured in tens of billions of dollars per year, if not hundreds of billions. If the conventional process improvements is able to achieve 20-25% cost improvement per year, in five years, the cost of panels based on conventional panels would be down to 25-30% of today's cost. A few hickups in the development of the new technology like yield or reliability issues can easily delay the mass deployment by a few years which will negate all cost benefits. Not to mention the possibility of cadmium prices going up if the volumes are picking up...

    And don't forget the cost of capital investment, which is already funded due to other "useful" applications in the silicon case. Most other technologies that tried to compete against silicon lost so far, not because of fundamental technical issues but because of the economics involved.

    I am not against developing new innovative technologies to achieve substantial improvements in the solar power area. However, it is best to keep the optimism about new and unproven technologies in control until they reach at least beta production stage...

  15. Re:Great news! by Rei · · Score: 4, Interesting

    Not really, surprisingly.

    Growing plants for fuel is far, far more destructive and less efficient than just turning the solar energy directly to electricity and operating off of that.

    --
    All them years of priest training, taken out by one bounty hunter.
  16. Re:Great news! by jollyreaper · · Score: 4, Funny

    Just think one day we can grow massive "pillars" in the earth, and these "pillars" can sequester carbon and be powered by the sun as they grow. Then as they reach a certain height and are no longer as efficient as they once were, we can take them down and use them as fuel. We can then plant new pillars to grow and use the by products from old burnt "pillars" to help the new ones grow. Perhaps then if we properly manage these "pillar farms" and modify the "pillars" just right we can have them absorb more carbon from the air than they release when burned for fuel.

    But then we'd have these "pillars" all over the place and would not be able to see the forest for them.

    --
    Kwisatz Haderach
    Sell the spice to CHOAM
    This Mahdi took Shaddam's Throne
  17. What about total installation cost? by IvyKing · · Score: 3, Insightful

    The cost of solars cell is low enough that infrastruture costs are a significant portion of the total installed cost. The quoted efficiency, 6%, implies that these cells would take up more area than silicon cells, and structiral support costs are proporional to area (I did see the text about possible doubling of efficiency). Another disadvantage to low efficiency cells is increased thermal loading.

  18. Re:Great news! by JustinOpinion · · Score: 4, Informative
    I don't think the pillars are acting as antennas in the way you're thinking. It's simpler than that. The pillars are just providing a higher surface area of interface between the light-absorbing material and the conducting material, and creating a shorter path for the electron-hole-pairs (EHP) to reach their respective conducting materials. Basically one of the main limitations in photovoltaics of this type is the short lifetime of the EHP before it recombines... having the pillars penetrate into the absorbing layers means the EHP have a shorter path to travel. From the paper:

    Conventional thin-film photovoltaics rely on the optical generation and separation of electron-hole pairs (EHPs) with an internal electric field, as shown in Fig. 1a. Among different factors, the absorption efficiency of the material and the minority carrier lifetime often determine the energy conversion efficiency15. In this regard, simulation studies have previously shown the advantages of three-dimensional (3D) cell structures, such as those using coaxially doped vertical nanopillar arrays, in improving the photocarrier separation and collection by orthogonalizing the direction of light absorption and EHPs separation (Fig. 1b)16.

    Later in the paper they discuss the light-absorbing properties of these kinds of pillar arrays:

    In addition, 3D nanopillar or nanowire arrays, similar to the ones used in this work, have been demonstrated in the past to exhibit unique optical absorption properties13,18. Similarly, we have observed reduced reflectivity from CdS nanopillar arrays especially when the inter-pillar distance is small (see Supplementary Fig. S6). This observation suggests that 3D nanopillar-based cell modules can potentially improve the light absorption while enhancing the carrier collection.

    References 13,18 are:
    L. Tsakalakos, J. Balch, J. Fronheiser, B. A. Korevaar, O. Sulima and J. Rand "Silicon nanowire solar cells". Appl. Phys. Lett. 91, 233117 (2007). doi 10.1063/1.2821113
    Hu, L. and Chen, G. "Analysis of optical absorption in silicon nanowire arrays for photovoltaic applications". Nano Lett. 7, 3249-3252 (2007). doi 10.1021/nl071018b

    Quoting from that second paper:

    We found that, in comparison to thin films, nanowire array based solar cells have an intrinsic antireflection effect that increases absorption in short wavelength range.

    Essentially the nanowire arrays are acting as anti-reflection coatings and allowing the light to instead be absorbed.

  19. Re:Wait a second by DrJimbo · · Score: 3, Interesting

    Cap and Trade is competition through breaking-your-competitors'-kneecaps.

    If you don't like cap and trade, then what would you suggest should replace it?

    The problem is that even though unregulated free markets are good in many situations, there are some situations where they make things worse, not better. Situations such as the Tragedy of the Commons where individuals are sharing a limited resource. Some argue (correctly, I believe) that the reason free markets fail in these situations is that the cost of depleting the shared resource is not correctly accounted for. IMO the obvious solution is to tax the use of the shared resource in order to give it a realistic cost. But I suspect you would find taxation even more onerous than cap and trade.

    So how do you propose we deal with the problem of limited shared resources? We will be facing more and more of these situations as long as we are stuck on this planet and if we simply ignore the problem and give free markets free rein then we will be no better than a bunch of lemmings rushing towards the cliff to their doom.

    --
    We don't see the world as it is, we see it as we are.
    -- Anais Nin