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Friday, May 11, 2007

Solar Power at Half the Cost

Continued from page 1

By Kevin Bullis
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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."
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DOE photovoltaics solar solar power

Comments

  • Total $ / net KWH
    nekote on 05/11/2007 at 7:36 AM
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    Total $ / net KWH

    Always the key question.
    The delivered price of the energy.
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  • Heat tranfer
    halcorn on 05/11/2007 at 8:31 AM
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    An issue may be with the heat generated by the panel to the roof.  How is that handled in this situation? 
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    • Re: Heat tranfer
      kearns on 05/11/2007 at 9:57 AM
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      Why not consider doing something with the waste heat, like heating water.  Solar cogeneration is seldom considered.  I wonder why not.
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      • Re: Heat tranfer
        tonycecala on 05/11/2007 at 11:47 AM
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        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".
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        • Re: Heat tranfer
          kearns on 05/11/2007 at 2:04 PM
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          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.
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          • Re: Heat tranfer
            gildwal on 05/12/2007 at 6:00 PM
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            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.
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      • Solar cogen great idea, but water a bear
        nekote on 05/12/2007 at 12:52 PM
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        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.
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      • Re: Heat tranfer
        FarhadA on 05/14/2007 at 4:36 AM
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        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
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      • Re: Heat tranfer
        solarbob on 05/15/2007 at 2:54 AM
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        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.
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      • Re: Heat tranfer
        ytterbius on 07/12/2007 at 11:49 PM
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        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.
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        • Re: Heat tranfer
          Elroch on 08/09/2007 at 7:42 PM
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          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.
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    • Re: Heat tranfer
      mbloore on 05/11/2007 at 8:25 PM
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      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.
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      • Re: Heat tranfer
        aymeric on 05/14/2007 at 9:11 AM
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        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)
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        • Re: Heat tranfer
          jaller on 06/10/2007 at 4:54 AM
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          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.
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          • Re: Heat tranfer
            cassamm on 06/24/2007 at 11:43 AM
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            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.
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    • Re: Heat tranfer
      fladale on 01/01/2009 at 9:40 PM
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      Wouldn't the same sunlight hit the roof anyway  The solar panel would not generate any heat of its own
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  • $/kw and life
    asdar on 05/11/2007 at 8:32 AM
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    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.
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  • EROI
    karlhedderich on 05/11/2007 at 9:42 AM
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    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.
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    • Re: EROI
      kjblack on 05/14/2007 at 3:10 AM
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      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.
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      • Re: EROI
        Elroch on 08/09/2007 at 7:46 PM
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        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.
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  • Hail
    bkshilo on 05/11/2007 at 2:20 PM
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    How resistant is it to hail?  Have to think about that, especially since I live in the MidWest.
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  • similar invention
    paultz on 05/11/2007 at 3:04 PM
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    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
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    • That invention available, NOW
      nekote on 05/12/2007 at 12:25 PM
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      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.
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  • expected improvements
    Jeff on 05/12/2007 at 5:29 AM
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    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. 
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  • PV and collectors for same
    Silacon on 05/12/2007 at 12:43 PM
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    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 
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  • sun tracking
    rhapsodyinglue on 05/13/2007 at 8:44 PM
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    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.
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  • Best companies SolFocus and EnergyInnovations
    carlp on 05/14/2007 at 12:28 PM
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    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
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    • Re: Best companies SolFocus and EnergyInnovations
      slapstick on 05/14/2007 at 2:59 PM
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      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.
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      • Re: Best companies SolFocus and EnergyInnovations
        solarbob on 05/15/2007 at 2:40 AM
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        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.
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  • Rod Configuration
    bhjohnson60 on 06/08/2007 at 1:01 PM
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