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Power Science

New Solar Panel Design Traps More Light 334

Posted by CowboyNeal
from the thousand-points-of-light dept.
GoSun wrote in with an article about new solar panels that opens, "Sunlight has never really caught fire as a power source, mostly because generating electricity with solar cells is more expensive and less efficient than some conventional sources. But a new solar panel unveiled this month by the Georgia Tech Research Institute hopes to brighten the future of the energy source." The new panels are able to produce sixty times the current of traditional models.
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New Solar Panel Design Traps More Light

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  • by Anonymous Coward on Thursday April 12, 2007 @11:01PM (#18713499)
    you don't want it bright, if it reflects light that's unused energy!
    you want a dim future
  • by Anonymous Coward on Thursday April 12, 2007 @11:01PM (#18713503)
    60 times the current, at 1/60th of the voltage. They're working hard to achieve the next milestone which is 100 times the current (at 1/100th voltage) before Xmas ... in space.
    • Then maybe I can use it to power my infinite miles-per-gallon-of-gasoline car!
    • Wrong way (Score:3, Interesting)

      by mdsolar (1045926)
      Actually, boosting the current is just the wrong way to go since they are having trouble with resistance. So, they do want to get the voltage up (not churned out) to help reduce the Ohmic losses (I^2R). With detectors, you usually put on a bias to help get the defects that are causing the resistance filled up, but for power generations you need to rely on the dopant gradiant alone which is probably pretty ragged after they fabricate their nano-posts.
      --
      Eat the reflectance and get it now: http://mdsolar.blo [blogspot.com]
  • by Anonymous Coward on Thursday April 12, 2007 @11:01PM (#18713505)
    Sunlight has never really caught fire as a power source

    Well, I always saw that as a good thing, I don't know about everyone else here...
  • *yawn* (Score:4, Informative)

    by Spazntwich (208070) on Thursday April 12, 2007 @11:02PM (#18713509)
    From TFA:

    But current is only half the equation. To generate electricity, a cell has to churn out voltage as well.

    And so far, that's where Ready's invention has fallen short. There's still too much resistance within the cell to produce the type of electricity that's needed. But he said he'll now focus on reworking the interface to smooth out the kinks.

    This is non-news. Multi-layered cells have been talked about forever, and haven't they all previously run into similar issues?
    • (*yawn*)* (Score:5, Funny)

      by Anonymous Coward on Thursday April 12, 2007 @11:08PM (#18713575)
      Yawn. Posting about how a supposed innovation is actually several years old has been done before. Didn't we just read a post titled *yawn* yesterday?
    • not quite (Score:5, Informative)

      by minuszero (922125) on Friday April 13, 2007 @04:54AM (#18715625)
      Actually, this approach is a different one to the multi-layered aproach you are probably referring to.

      Said multi-layered approaches use multiple pn junctions with differing band-gaps, all on top of one another. This allows them to capture a broader spectrum of incoming light energies, thus increasing efficiency.

      The approach referred to in this article is attacking a different problem - using a 3-D 'nano-tower' construction for the pn junctions in order to minimise the reflection of light, thus capturing more of it and therfore being more efficient.

      While I'll agree that even this idea for such nano-cells has been around for a little while, it is still in very early stages of development, and has a long way to go. It is encouraging to see apparent evidence that the concept does work, however!
  • by EmbeddedJanitor (597831) on Thursday April 12, 2007 @11:05PM (#18713545)
    The power convesion ratio is not really that important in itself. The only really important measure is $/watt.

    If you can get low $/watts with low efficiency that would be OK. Tile your house with the stuff, use it as the external covering for buildings.

    That is one of the major problems with PV showcases like the Australian solar race. they push efficiency more than $/watts which is my the winning cars cost hundreds of thousands of dollars.

    • Bullwhoey (Score:4, Insightful)

      by SuperBanana (662181) on Friday April 13, 2007 @12:58AM (#18714417)

      The power convesion ratio is not really that important in itself. The only really important measure is $/watt.

      Right, and the only thing that matters with hard drives is $/GB ratio? People don't size systems based purely on $ figures; required output weighs into the equation heavily, since systems usually pay themselves back pretty fast. It doesn't matter when you have a whole hillside or roof, but otherwise, size is important, and the more efficient a panel, (duh), the smaller. That matters for space availability and wind loads.

      For example, it's not practical to put solar panels on the roof of a UPS truck; you could cover the entire roof, and even on a sunny day, you probably still wouldn't be able to supply enough energy to keep it going on a day's worth of deliveries. Increasing the efficiency matters here. Likewise for say, putting a solar panel on the back of a cell phone.

      The other arena this helps in? Wind loads. If you have a residential system with several panels on a tracking frame, if the panels can be half the size, that means a cheaper frame and tracking system, and less of an eyesore in your back yard. Or, alternatively, twice as much power from the same frame.

      What really matters is retail availability. I've been reading about advances in solar panel technology for years, and it's dripping into the consumer market like molasses. Why? Well, for one thing, oil companies are snapping up solar intellectual property and companies like crazy...

      • Re: (Score:3, Insightful)

        by nietsch (112711)
        even if efficiency was 100%, a UPS would could still not be powered by sunlight only for any practical purposes there is only a limited amount of energy in sunshine, and it will never be enough to power very usefull vehicles.
        If you assume that evolution always finds the cheapest solution, you can conclude that it's cheaper to have low efficiency photoconversion, as plants are less efficient than current PV cells. To compensate you just need lots of surface (leaves) which makes you stationary for practical r
        • Re: (Score:3, Insightful)

          by maxume (22995)
          Evolution is very sensitive to local minimums; it can easily get 'stuck' with bad optimizations(because, say, a tree, hoards local resources, more efficient photosynthesizers can't easily grow underneath it).
    • This isn't the whole story. Efficiency is very important because it determines what amount of surface area you need for a particular amount of power. It does us very little good to invent a virtually cost free type of solar power if the surface area (land) requirements are enormous (in which case it is far from free because no matter how cheap the material, maintenance will be a bitch).

      If the cheapest alternative is to cover a geographically significant area of land with collectors, the alteration in

    • by s_p_oneil (795792) on Friday April 13, 2007 @01:13AM (#18714517) Homepage
      No, $/Watt is NOT the only important measure for PV cells. Here are some cases where it is not (these examples are extreme to drive the point home):

      1) What if I could sell you PV cells that cost 1% the $/Watt of traditional PV cells, but 1 acre of it only generated 100 Watts? Now you need an acre of land to power each 100 Watt light bulb.

      2) What if I could sell you PV cells that cost 1% the $/Watt of traditional PV cells without taking up that much space, but they required 10 times as much maintenance after they were installed, perhaps even needing to be replaced every year or 6 months? You going to pay someone to keep reinstalling it?

      3) What if I could sell you a bunch of super-cheap reflectors to focus the sunlight onto one tiny but expensive PV cell? If my parents, or possibly even my neighbors, had one of these when I was a pre-teen, I'll bet I would've been up on the roof with a big mirror or lens playing around with my nifty "fire ray", and I would not have been alone in trying that. And what about pine trees? I wouldn't want pine needles bursting into flame as they fall through the concentrator on my roof, so the concentrators would need some sort of enclosure, which limits their size, and thus their power.

      I might be able to come up with other scenarios if I give it more thought, but I think you get the point. The PV cell's $/Watt cost is not the only cost to consider.
      • by ArsonSmith (13997)
        Sorry but realestate and maintenance both need to be included in your $/watt. An acre of land is expensive, the roof of your house is cheap.
      • by BarneyL (578636) on Friday April 13, 2007 @09:02AM (#18717103)
        Surely the $/Watt includes all the things you have just thrown in so when calculating your examples:

        1) The cost of the land would have to be taken in to account
        2) The cost of maintenance would be taken in to account
        3) The cost of legal fees and vet bills for treating spontaniously combusted neigbours pets would be taken in to account.

        The parent's point still holds, the important factor is the total cost of a PV system (installation, land space, maintenance and enclosure costs included) divided by the power it produces.

    • That is one of the major problems with PV showcases like the Australian solar race. they push efficiency more than $/watts which is my the winning cars cost hundreds of thousands of dollars.

      It matters a heck of a lot for my boat... I've only got a limited area available for solar cells... and a required consumption of X Watts per weekend which has to be topped up during the week. I'd love cheaper solar cells... but for some weird reason, the manufacturers seem to think us Yacht owners are made of money...

    • by evilviper (135110)

      The power convesion ratio is not really that important in itself.

      If you ever want a solar-powered car, it is.

      Not to mention satellites, where money is no object.

      And for any other similar (portable/compact) objects as well... RVs or other camping gear... Unmanned airplanes... Ships...

      Price matters a lot, but often times, surface area matters more.
    • The power conversion ratio is not really that important in itself. The only really important measure is $/watt

      $/watt is important, but a couple other characteristics come into play. Anything from footprint, maintenance, weight, to longevity can greatly influence a particular implementation of solar energy. A number of homes are unable to implement rooftop solar without installing additional roof bracing.

      BBH
  • by khallow (566160) on Thursday April 12, 2007 @11:07PM (#18713567)
    Recall that most solar cells on the market acquire 10-20% of the energy that falls on them. Electrically, power is current times voltage. So this is a bogus claim. There's no point to claiming that the solar cell gets "60 times the current" while ignoring voltage (which dropped by an unspecified amount), and ignoring that there's only a theoretical factor of 5 to 10 possible improvement in power over current solar cells.
    • by Toe, The (545098) on Thursday April 12, 2007 @11:15PM (#18713635)
      There was a Monty Python episode where they were comparing penguin brains to human brains. They found that if the penguin were scaled up to human size, its brain was still smaller than a human brain. But -- and this is the important part -- it's larger than it was before!
  • 60 is misleading (Score:5, Insightful)

    by Harmonious Botch (921977) * on Thursday April 12, 2007 @11:09PM (#18713583) Homepage Journal
    It's power that matters, not current.
    The best solar cells today get about 13 watts / square foot. The toatl power available on a sunny day with near perpendicular light is 130-140 watts. So efficiency is near 10%. The best a new design can do is about 10-11 fold increase, not 60.
    • Re: (Score:3, Insightful)

      by anagama (611277)
      Actually, it sounds like what is happening is that nano-towers increase surface area. The FA is short on details but perhaps they are increasing the surface area sixty-fold by making it very very crinkly. In other words, a tile that is 1 sq ft may have an effective surface of 60 sq ft. In this way, they could get 60 times the juice from a tile with the same outside dimensions as a flat solar cell. Even so, the crinkly cell might still be only 10% efficient -- the extra electricity is simply a factor of
  • by rsilvergun (571051) on Thursday April 12, 2007 @11:10PM (#18713587)
    I've heard that the energy cost of making the panels is greater than the amount of power they generate in their lifetime. Don't know if that's true though, but it takes energy to make the panels, and they do wear out / break.
    • by bahwi (43111)
      Yes, but so do coal and oil plants, as well a nuclear. But no, they aren't quite green yet, but let technology improve and demand improve and let them get there. (If we never improved powers such as coal and oil they would not be considered a valuable source now)
    • Outdated canard (Score:5, Informative)

      by StefanJ (88986) on Thursday April 12, 2007 @11:27PM (#18713735) Homepage Journal
      I'm tempted to say "Cripes, This Again," because it comes up in almost every discussion about solar cells.

      Instead I'll say: That may have been true once, but it isn't any more. It will become less and less true with time, as learning economies and economies of scale come into effect.
    • by evanbd (210358) on Thursday April 12, 2007 @11:39PM (#18713833)

      Electric power delivered to me at home is about $0.10/kwHr. Solar panels are about $5/w for the panel or a bit less. Grid tie inverters are a bit under $1/w (at least in the low kilowatts range). It's a bit pricier if you want batteries and completely off-grid, but I'll assume a simple grid tie system designed to reduce your utility bill.

      That means your solar panel needs to produce 60,000 wHr of electricity per watt to pay for itself, ie it needs to operate for 60k sunny hours. That's about 25 years or so, in a reasonably sunny mid-latitude climate. That's about the life of the solar panel.

      Now, that only sort of answers how green they are. In terms of carbon budget, they probably come out ahead -- not all the cost of the solar panel pays for the energy to make it, there are other costs as well. In terms of total pollution, I don't really know -- there are some nasty chemicals involved, but I think the silicon industry in general is pretty good about disposal (I don't know details off hand, sorry). I don't think there are any subsidies on the manufacturing, just tax credits and such when you buy them, so I think I've fully accounted the costs.

      So, overall, I'd guess they're marginally greener than the alternatives. Solar panel prices are falling rapidly, which means they're getting greener to make (at least if we assume manufacturing techniques aren't getting messier). I'd guess they start to come out clearly ahead in the next couple years.

    • by Animats (122034) on Friday April 13, 2007 @12:16AM (#18714135) Homepage

      When Mark Pinto of Applied Materials spoke at Stanford in EE380 two weeks ago, he said that the current energy payback time on their solar panels is two years, and they're trying to get that down to six months. Some of the fab steps borrowed from semiconductor processing, where the areas aren't so large, can be improved.

    • by taharvey (625577) on Friday April 13, 2007 @01:04AM (#18714455)
      This is one of those grand myths that the public just can't shake. Photovoltaic's have a very good energy return on investment (EROI).

      The energy payback peroid for various PV cell types are:
      Crystal Silicon: 3.3 years [chem.uu.nl]
      Multicrystal Si: 0.8 years [chem.uu.nl]
      CIS: 0.4 years [chem.uu.nl]

      To put that is perspective of EROI:
      Photovoltaics (Si): 60:1 - 10:1 (based on above)
      Wind: 60:1 [awea.org]
      Coal(US average): 9:1 [eroei.com]
      Nuclear (light water): 4:1 [eroei.com]
      Oil (mid-east): 10:1 - 30:1 [eroei.com]
      Oil (US): 3:1 or less [holon.se]

      And that is keeping in mind that the lifespan of PV is calculated at 30 years, an arbitrary number picked to equalize it with the life of a coal or nuclear power plant, however are panel warranties are 20-30 years alone. There is no reason to believe that the average lifespan of a PV panel won't be 40-60 years or more.
      • Lifespan of silicon (Score:3, Informative)

        by mdsolar (1045926)
        The typical warranties for panels say that they will produce within 80% of their rated power over 25 years. The main cause of the degradation is defects in the crystal structure of the silicon created by cosmic rays. There is a very strong after market for solar panels because they can be used where there is plenty of land, say at a dairy or ranch, where ground mounting is not a problem.

        I like your comparison of EROI. I recently calculated the relative burden on transportation infrastrcuture for solar
  • by rolfwind (528248) on Thursday April 12, 2007 @11:11PM (#18713591)

    Sunlight has never really caught fire as a power source


    Besides the bad pun... you obviously have never used magnifying glasses on poor helpless insects...
  • by Anonymous Coward
    The op article was vague and didn't have the pretty picture the one below has:

    http://gtresearchnews.gatech.edu/newsrelease/3d-so lar.htm [gatech.edu]
  • Cost comparisons (Score:5, Interesting)

    by aegl (1041528) on Thursday April 12, 2007 @11:54PM (#18713959)
    People keep dismissing solar because it can't compete in price against traditional large scale ways of generating electricity.

    But it doesn't matter to me that some hydro-electric plant far from my house is making power at $0.02 per kWh, what matters to my economic reality is that my local power company charges just over $0.08 for the first dozen kWh delivered each day and then has a sliding scale that goes up to $0.36 kWh for increased amounts of power.

    Before I installed solar panels a high percentage of my power was costing me that top rate. So the relevent economic calculation for me is the cost to install my panels divided by the expected number of kWh that they will generate across their lifetime. This number comes out at about $0.16 per kWh. So I'm better than breaking even now, and assuming that energy prices continue to rise, I'll do even better in years to come.

    The final kicker in the equation is that I've switched to a time-of-use tariff so across the summer the power company will credit me with $0.209 for excess power that I generate in peak hours (between 1pm and 7pm), and $0.112 for partial-peak (10am-1pm + 7pm-9pm).

    If I'd taken the capital that I used to install the panels and invested it instead, I'd have to maintain a >19% annual pre-tax rate of return to beat the panels. Possible, but extremely unlikely (especially with my stock-picking track record!).

    • by _Sharp'r_ (649297)
      Hard Money lending. Generally a minimum $50K investment, but returns a minimum 24%, in my experience averages closer to 30% once they go late and start paying 2%/month late fees on top of the interest. (Most people underestimate how long its going to take them to get their conventional commercial financing.)

      Since a title company handles it all and insures the title, you get a first position mortgage (trust deed) recorded and shouldn't loan on anything higher than a 75% loan-to-value ratio, its also much les
    • What kind of lifetime are you expecting?

      What about things like theft, hail, wind, tree branches, neighborhood kids with baseballs?

      I know it could be a good investment, but these risks somewhat concern me if it will take 10-20 years to pay it off.
      • by cliffski (65094)
        Insurance surely?
        After all, people spend a fortune on double glazing, and that has exactly the same risks. I don't know how long it takes for doubvle glazing to pay for itself through lower heating bills, but I'm pretty sure its quite a while too.
  • Tag (Score:5, Funny)

    by Archangel Michael (180766) on Thursday April 12, 2007 @11:56PM (#18713973) Journal
    Why isn't this tagged "itsatrap"???
  • Great (Score:5, Funny)

    by TheRealMindChild (743925) on Friday April 13, 2007 @12:05AM (#18714057) Homepage Journal
    Now all we need is something that can trap more girls and well be set!
  • by dyslexicbunny (940925) on Friday April 13, 2007 @12:06AM (#18714061)
    It's like a third grader's book report... Why don't we just get the water from the well... from GTRI's site [gatech.edu]
  • by Reality Master 101 (179095) <RealityMaster101&gmail,com> on Friday April 13, 2007 @12:09AM (#18714085) Homepage Journal
    Maybe a power engineer can answer this... the obvious way to build a solar power plant is to take a whole slew of lenses and focus them on a water tank, and then turn a turbine. Given that heat -> power is a fairly mature technology, wouldn't that be more efficient than solar cells?
    • The tracking motors etc for the mirrors are the deal breaker.

      The only number that matters is $/watt. If they're cheap but inefficient we just cover the whole roof. If we run out of roof there is plenty of space in the western US.

    • by dhasenan (758719)
      The photoelectric effect is more direct, so it likely has less energy loss. Specifically, the hot water tank has a lot of surface area exposed to cool air that sucks energy from it. So, no, that's a pretty lousy way to make electricity.
    • by ookabooka (731013)
      Given that heat -> power is a fairly mature technology, wouldn't that be more efficient than solar cells?

      What about Molten Salt [fsu.edu]
    • Re: (Score:3, Informative)

      by joib (70841)
      This is called concentrating solar power (CSP). See e.g. http://en.wikipedia.org/wiki/Solar_thermal_energy [wikipedia.org]

      For utility scale systems they seems to be more cost efficient than big arrays of solar cells. The downside is that they require direct solar radiation so they are very inefficient on a cloudy day.
    • Re: (Score:2, Interesting)

      by BlackPignouf (1017012)
      It indeed already exists!

      Either with solar ponds (http://en.wikipedia.org/wiki/Solar_pond) and ORC (http://en.wikipedia.org/wiki/Rankine_cycle), solar panels and DACM (diffusion absorption cooling machine), solar panels and ORC, or paraboloid solar panels ans Stirling engines (http://engnet.anu.edu.au/DEresearch/solarthermal/ images/basics/sb.jpg).
  • A Better $TRILLION (Score:2, Insightful)

    by Doc Ruby (173196)
    Man, I wish we'd spent that Iraq War $TRILLION on solar research instead.

    If we just got all its 212 possible oil barrels, that would have been $4.72 a barrel (enough to get 50M Americans to vote for it), but we probably won't get any of it now - unless we buy it from Iran.

    That 750Pj could come from the Sun (at 1KW:m^2) into 4000K square miles (0.1% of the US total area) in 2.5 years. At 25% efficiency, that would be 10 years. We're already halfway through that alternate decade, we've only wasted huge amount
    • by Stellian (673475)

      Investing $250M per square mile in American solar production would have actually secured America, especially from the oil terrorists, at home and abroad.
      Oil has much less to do with energy - we can already get much cheaper energy from atomic, hydroelectric and even coal plants.
      Oil means high energy in a small mass, gasoline, and no amount of solar energy research could replace gasoline, unless you make all your driving in the sun.
  • Dumb question (Score:5, Interesting)

    by lawpoop (604919) on Friday April 13, 2007 @12:33AM (#18714235) Homepage Journal
    Hey, if you have solar panels on your roof, how often to you have to wash them? Do they develop a film that reduces their efficiency?
    • by mdsolar (1045926)
      Usually rain takes care of this. A long dry dusty period could reduce the efficiency. Snow cover can also be a problem.
      --
      Rent solar and only pay for what the system produces: http://mdsolar.blogspot.com/2007/01/slashdot-users -selling-solar.html [blogspot.com]
    • Re: (Score:3, Interesting)

      by Anonymous Coward
      I've had solar panels on my roof for 1.5 years, I did not try cleaning them until 3 months ago. Over last summer I estimate I lost 1 to 2 KWHr / day because they were not clean (there was rain in October which cleaned and increased the output.) What caused me to clean them was trying to understand how much energy was falling on my system and where the losses were. In one year my 18 x 170W panels generated 5MWHr, (San Jose, reasonably sunny), which at 10 cents / KWHr only represents $500. The system cost
  • That's not news (Score:4, Informative)

    by mkwalker (471266) on Friday April 13, 2007 @01:22AM (#18714567)
    Where's the news in a half finished project that doesn't deliver any benefits (so far) on existing technologies? Who was the fool that got suckered into producing an infomercial?

    This is news: http://www.abc.net.au/catalyst/stories/s1865651.ht m [abc.net.au]

    Sliver cell solar technology. This was on Australian TV in March. Generating the same amount of power using a fraction of the silicon required today. Brilliant.
  • including pretty pictures so we can see what TFA is talking about: Science Daily [sciencedaily.com]
  • The new panels are able to produce sixty times the current of traditional models.

    Even low-quality solar cells today have around 10% efficiency. Either these things produce a much lower voltage than standard cells, or those claims are bogus.

    Anyway. The "problem" with solar cells isn't the conversion efficiency, it's the cost to produce them. If they had come up with a way to make solar cells that are comparable to current models in efficiency but come at 1/60th the cost, they'd have a story.

  • How does this work (Score:3, Interesting)

    by hcdejong (561314) <hobbes@xmsnBLUEet.nl minus berry> on Friday April 13, 2007 @02:59AM (#18715065)
    TFA says they increase the surface area without increasing the dimensions of the panel. But that's not enough.
    Let's say that the 3D panel has 10 times the surface area of a flat panel, with the same dimensions. It still receives the same 1400 W/sq m as a flat solar panel, so the amount of solar power going into each sq cm of the panel has to drop to 1/10. It seems to me that the 3D panel wouldn't produce any more power than the flat design.
    So there has to be a second effect at work. Let's see if we can find a better article than the information-starved FA? this article [sciencedaily.com] claims that the efficiency is increased due to reflections, i.e. each photon has more than one chance of being caught by a PN junction. Ah.

    I wonder if this would work on macro scale, by placing two panels at a 45 degree angle to the sun, and 90 degrees to each other, like this \ /. That would double the efficiency of both panels, without the drawback of using nanoscale structures. The panels would have to track the sun for this to work, though.

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