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Solar Power at Half the Cost

Continued from page 1

By Kevin Bullis

Friday, May 11, 2007

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But the ease of installation could help convince solar installers to use the technology, says Craig Cornelius, the technology manager for the Department of Energy's (DOE) solar-energy technology program. DOE recently announced $168 million in funding for 13 solar projects, under which Soliant will receive up to $4 million. Cornelius says that the lower installation costs will help reduce the overall costs of solar power from the modules.

Cornelius thinks that some customers, such as those with plenty of roof space, will opt for cheaper, thin-film solar panels, which in some cases can double as shingles, but are less efficient than conventional solar panels. But for those who need more power for the space they have, Cornelius says that Soliant's approach may prove the best option. Its modules produce as much power as conventional flat panels but are less expensive, using 88 percent less silicon. The company's next-generation system would be even better, producing three times as much power per area.

To test the panels, Soliant is working with DOE and Sun Edison, an established solar-system installer and operator based in Beltsville, MD. The second-generation system will be even more challenging to develop because light will be focused on a smaller area, requiring better tracking of the sun. Soliant will also be working with Emanuel Sachs, professor of mechanical engineering at MIT, to improve manufacturing techniques and the system for aiming the concentrators.

"In some ways, what's interesting about [Soliant's] approach is [that] the engineering issues they have to solve are relatively mundane," Cornelius says. "This is one of the projects that I'm most excited about in our whole portfolio."

Comments

  • Total $ / net KWH
    Total $ / net KWH

    Always the key question.
    The delivered price of the energy.
    Rate this comment: 12345

    nekote
    05/11/2007
    Posts:139
    Avg Rating:
    3/5
  • Heat tranfer
    An issue may be with the heat generated by the panel to the roof.  How is that handled in this situation? 
    Rate this comment: 12345

    halcorn
    05/11/2007
    Posts:1
    • Re: Heat tranfer
      Why not consider doing something with the waste heat, like heating water.  Solar cogeneration is seldom considered.  I wonder why not.
      Rate this comment: 12345

      kearns
      05/11/2007
      Posts:29
      Avg Rating:
      4/5
      • Re: Heat tranfer
        That is a great idea. How long before we see integrated water heating and photovoltaic systems? You could image a system that handles the infrared separately from the other spectra. Using each part of the spectrum to its fullest advantage and reducing "waste heat".
        Rate this comment: 12345

        tonycecala
        05/11/2007
        Posts:2
        Avg Rating:
        3/5
        • Re: Heat tranfer
          Thanks.  I'm sure it would boost overall efficiency somewhat.  Cogenerators using gasoline engines are old hat but why those tricks aren't being used with photovotaics and hot water systems in the home are beyond me.  Gasoline powered cogenerators burn gas, generate electricity, and use the hot water from the engine block to warm a building.  The overall efficiencies can be very high.
          Rate this comment: 12345

          kearns
          05/11/2007
          Posts:29
          Avg Rating:
          4/5
          • Re: Heat tranfer
            First the infrared heat and UV heat is block (56%) with a polymer substance, same as found in the new windows films.  Then the rest of the heat is dissipated with heat sinks.  There are several companies that have solved this problem and are waiting for funds to going into the production phase.   We will most likely no see any products until the completion of the Bush administration.
            Rate this comment: 12345

            gildwal
            05/12/2007
            Posts:1
      • Solar cogen great idea, but water a bear
        Solar PV cogeneration sounds like a great idea.

        Intense concentrators, like www.greenandgoldenergy.com.au's 500:1 fresnel lens system, absolutely have to have a method to dissipate that tremendous thermal load, otherwise the silicon PV "melts".  Essentially, they're deliberately using the aluminum structure as a heat sink to disipate that heat.

        Using water sounds great.
        But water always has the potential leakage issue.
        A bigger deal because of the proximity of electrical devices.

        Worse yet, at these heat / potential temperature levels, there is the danger of a steam explosion.
        An all too real and really seriously bad thing.

        Probably have to have a wicked good safety system.

        Or some sort of elegant / cool totally failsafe passive intermediary heat transfer system.
        Rate this comment: 12345

        nekote
        05/12/2007
        Posts:139
        Avg Rating:
        3/5
      • Re: Heat tranfer
        HI,
        There are several German companies who combine the 2 technologies in a very interesting way. I don't remember the name but I have seen several installation of this type here in south of France where I live.

        Best regards,
        /Farhad
        Rate this comment: 12345

        FarhadA
        05/14/2007
        Posts:1
        Avg Rating:
        4/5
      • Re: Heat tranfer
        In addition to the plumbing issues, there is the problem that silicon solar cells are much less efficient when they get hot.  By the time you allow them to run at temperatures high enough to provide useful water heat, the electricity output has been seriously impacted (realize that the cells will run substantially hotter than the temperature of the "cooling" water).

        If you really need hot water, the tradeoff may be worthwhile.  But in many cases, it may be actually  be more cost effective to install separate PV and solar hot water systems.
        Rate this comment: 12345

        solarbob
        05/15/2007
        Posts:2
        Avg Rating:
        5/5
      • Re: Heat tranfer
        There's a story on just this in the recent edition of "Alternative Energy Retailer."

        Check out the webpage http://www.aer-online.com/splash.phtml

        It's a paper magazine, and I don't know if you'll actually be able to get this particular article anymore, but it's free, and if you're into this stuff might be worth getting.
        Rate this comment: 12345

        ytterbius
        07/12/2007
        Posts:1
        • Re: Heat tranfer
          There is no need to heat water to a very high temperature. In fact, it would be possible to heat the water to a lower temperature to that required, and then complete the heating using a conventional method. One key issue is achieving the required rate of heat transfer with the solar cells running at as low a temperature as possible. Of course the rate of heat transfer is direcly dependent on the temperature difference of the source.
          Rate this comment: 12345

          Elroch
          08/09/2007
          Posts:33
          Avg Rating:
          3/5
    • Re: Heat tranfer
      unless a roof is mirrored it will be heated by the sun anyway, but all the heat will be wasted.  this diverts a little of that energy into electricity.

      so the roof will actually stay a bit cooler.
      Rate this comment: 12345

      mbloore
      05/11/2007
      Posts:28
      Avg Rating:
      4/5
      • Re: Heat tranfer
        How about all the heat that is generated by appliances in the house (ie: Refrigerator, oven, etc...we have to find a way to capture that energy as well)
        Rate this comment: 12345

        aymeric
        05/14/2007
        Posts:19
        Avg Rating:
        4/5
        • Re: Heat tranfer
          I'm glad that you're looking for novel ways to produce energy.  However, the two appliances you mentioned (a refrigerator and an oven) probably could not be used to harvest energy and efficiently produce electricity. 

          The purpose of a refrigerator is to remove heat from an interior chamber.  If you try to attach something to the hot area at the back of the fridge (for producing electricity), that would increase the thermal resistance and make it harder for the fridge to do its job of getting rid of heat from the inside compartment.  The fridge would have to consume additional electricity, more than you would be able to produce.

          As for the oven, it is possible to use it to generate electricity, but since you want the appliance to reach and maintain a nice high temperature (for cooking your food), I think the best choice would be to get an oven which is more insulated.  That way, the oven would be losing heat (to the kitchen environment) more slowly, and it would require less energy to maintain the high temperature and cook your food.  IF, after you finish cooking, you could attach some system which would cool your oven and produce electricity in the process, that might be worthwhile, but I think that the cost of such a system would be much higher than the value of the small amount of electricity it could produce. 

          Summary: Don't use your household appliances to make electricity.  Buy more efficient appliances.
          Rate this comment: 12345

          jaller
          06/10/2007
          Posts:1
          Avg Rating:
          5/5
          • Re: Heat tranfer
            One can combine the generic solar water heater with the PV concentrator system to get both the technical and the cost synergies. This basically mean sandwiching the PV system into the hot water panel, twixt the transparent glass/acrylic cover  and the water plumbing. Wherein the heat transfer medium is ordinary car water+antifreeze mix.

            As it circulates this mix cools the PV cells and transfers the solar heat into the heat sink being the in-house hotwater tank, via a heat exchanger.

            This then implies the auto industry absorbing the solar sector. After all in the manufacturing context the generic solar hotwater systems are the assembly of the car's windscreen, radiator,  plumbing and related components. Which is why Toyota and Fiat are the  biggest manufacturers of solar hot water heaters in Japan and Italy respectively. 

            For them to incorporate the PV panels is the logical next step.
            Rate this comment: 12345

            cassamm
            06/24/2007
            Posts:1
    • Re: Heat tranfer
      Wouldn't the same sunlight hit the roof anyway  The solar panel would not generate any heat of its own
      Rate this comment: 12345

      fladale
      01/01/2009
      Posts:1
  • $/kw and life
    There are moving parts in this, they say long life, but I wonder what that life is, and if replacements parts are something that will be available when you need them.

    Still, even with that, this is a fantastic development. I hope when they say it's comparable with grid, they mean without subsidies.
    Rate this comment: 12345

    asdar
    05/11/2007
    Posts:69
    Avg Rating:
    4/5
  • EROI
    What is the energy return on investment?  I have heard conflicting things about PV ranging from the just break even on EROI over their life time to they break even in a fraction of their life time.
    Rate this comment: 12345

    karlhedderic...
    05/11/2007
    Posts:10
    Avg Rating:
    5/5
    • Re: EROI
      Why is there a big deal about EROI?
      No one asks about EROI when they buy an automobile, truck, flat screen television, surround sound system.
      The solar system adds value to the property it is being installed on so that has be an incentive to purchase the unit.
      Rate this comment: 12345

      kjblack
      05/14/2007
      Posts:13
      Avg Rating:
      2/5
      • Re: EROI
        Firstly, the energy return on investment is absolutely fundamental to the role of solar energy in the energy economy. If it isn't positive, the devices do not improve sustainability at all.

        Secondly, modern photovoltaics do have a positive EROI, but it does take a long time to break even.
        Rate this comment: 12345

        Elroch
        08/09/2007
        Posts:33
        Avg Rating:
        3/5
  • Hail
    How resistant is it to hail?  Have to think about that, especially since I live in the MidWest.
    Rate this comment: 12345

    bkshilo
    05/11/2007
    Posts:18
    Avg Rating:
    4/5
  • similar invention
    see the website http://www.greenandgoldenergy.com.au/
    for a similar australian invention (the suncube)
    website contains
    a detailed discussion of the issues and economics
    Rate this comment: 12345

    paultz
    05/11/2007
    Posts:1
    • That invention available, NOW
      The www.greenandgoldenergy.com.au product, a 500:1 fresnel lens 2-axis concentrator 3J (triple junction) system is currently commercially available.
      A post mounted system, versus this "flat" "roof" system.

      An obvious potential competitor to this system.
      Rate this comment: 12345

      nekote
      05/12/2007
      Posts:139
      Avg Rating:
      3/5
  • expected improvements
    It is quite likely that immprovements in solar concentrators will occur as the cost of controllers (Moore's Law) and small motors decline and solar designers incorporate these improvements into solar systems. 
    Rate this comment: 12345

    Jeff
    05/12/2007
    Posts:3
  • PV and collectors for same
    We invented a system several years ago that accomplished the same idea without the need of the Acrylic lenses. Our system would track automatically, too.  We should talk soon.

    Charles G. Nutter, CEO Silacon.com 
    Rate this comment: 12345

    Silacon
    05/12/2007
    Posts:46
    Avg Rating:
    2/5
  • sun tracking
    It seems with this type of flat panel, even with the second generation able to pivot on two axis, it would need to be on a south facing pitched roof to track closely and get the most advantage from the concentrating.  Due to that and the loss of efficiency in indirect sunlight, I wonder if this really would pay off in most/many situations.

    If I were to consider putting one of these on my roof, it certainly doesn't seem easy to figure out  what the real average output would be over a year.
    Rate this comment: 12345

    rhapsodyingl...
    05/13/2007
    Posts:59
    Avg Rating:
    4/5
  • Best companies SolFocus and EnergyInnovations
    The best companies in this space are SolFocus which has a thiner safer cheaper concentrator with fewer moving parts.
    http://solfocus.com/technology.html

    And Energy Innovations which has the SunFlower that fulfills the dreams of an earlier poster about using heat energy in a heat engine as well as visible energy in a PV cell.
    http://www.energyinnovations.com/sunflower.html
    Rate this comment: 12345

    carlp
    05/14/2007
    Posts:3
    Avg Rating:
    5/5
    • Re: Best companies SolFocus and EnergyInnovations
      The sunflower? Not only was that bulky and completely impractical, it was just plain old ugly.

      I hear EI is coming out with a new design, but if its anything like the sunflower it has about zero chance of succeeding. Solfocus has some promise, I think they are still a lot further from commercial production though. We'll see.
      Rate this comment: 12345

      slapstick
      05/14/2007
      Posts:1
      • Re: Best companies SolFocus and EnergyInnovations
        Good points.  Also, be aware that the SolFocus product has more moving parts than they let on.  Above a factor of few in concentration, there's no way around the basic need to track, no matter how small or clever the optics are.

        That said, the two products (SolFocus and Soliant) really serve different markets.  The Soliant product targets flat roofs, whereas the SolFocus product targets applications where a pole mount is acceptable.
        Rate this comment: 12345

        solarbob
        05/15/2007
        Posts:2
        Avg Rating:
        5/5
  • Rod Configuration
    I am not as familiar with solar cells as most of you, however, if the photo-voltaic cells can be made as a rod or tube and that is placed down the center of a collecting/reflecting trough, it seems to me that tracking becomes a non-issue.  Then you only need to adjust the angle of the panel to maintain the 90 degree angle for maximum exposure.  Is that so?
    Rate this comment: 12345

    bhjohnson60
    06/08/2007
    Posts:1
    • Re: Rod Configuration
      I believe you are essentially correct; this is basically the approach taken by large solar thermal trough collectors installed in California.  (Why isn't there more interest/discussion about thermo-electric generation?)  However, your surface/cell multiplier is not squared, but linear, so you need more Expensive(!) PV cell area.  (You also lose that small percent at the ends of the troughs, but let's assume the troughs are long enough to neglect this effect.)
      Rate this comment: 12345

      YogaMan
      06/27/2007
      Posts:2

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