Technology Review - Published By MIT
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Tuesday, April 25, 2006

Holographic Solar

A novel approach to concentrating sunlight could cut solar panel costs.

By Prachi Patel-Predd
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Rows of silicon solar cells alternate with rows of transparent holograms in Prism Solar's concentrators. (Courtesy of Prism Solar)

The main limitation of solar power right now is cost, because the crystalline silicon used to make most solar photovoltaic (PV) cells is very expensive. One approach to overcoming this cost factor is to concentrate light from the sun using mirrors or lenses, thereby reducing the total area of silicon needed to produce a given amount of electricity. But traditional light concentrators are bulky and unattractive -- less than ideal for use on suburban rooftops.

Now Prism Solar Technologies of Stone Ridge, NY, has developed a proof-of-concept solar module that uses holograms to concentrate light, possibly cutting the cost of solar modules by as much as 75 percent, making them competitive with electricity generated from fossil fuels.

The new technology replaces unsightly concentrators with sleek flat panels laminated with holograms. The panels, says Rick Lewandowski, the company's president and CEO, are a "more elegant solution" to traditional concentrators, and can be installed on rooftops -- or even incorporated into windows and glass doors.

The system needs 25 to 85 percent less silicon than a crystalline silicon panel of comparable wattage, Lewandowski says, because the photovoltaic material need not cover the entire surface of a solar panel. Instead, the PV material is arranged in several rows. A layer of holograms -- laser-created patterns that diffract light -- directs light into a layer of glass where it continues to reflect off the inside surface of the glass until it finds its way to one of the strips of PV silicon. Reducing the PV material needed could bring down costs from about $4 per watt to $1.50 for crystalline silicon panels, he says.

The company is expecting to pull in another $6 million from interested venture capitalists and start manufacturing its first-generation modules by the end of the year, selling them at about $2.40 per watt. Next-generation modules with more advanced technology should bring down the cost further.

In their ability to concentrate light, holograms are not as powerful as conventional concentrators. They can multiply the amount of light falling on the cells only by as much as a factor of 10, whereas lens-based systems can increase light by a factor of 100, and some even up to 1,000.

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Comments

  • Hail Stones
    Guest (Sam DeLay) on 04/25/2006 at 12:00 AM
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    We had some as big as baseballs in Tennessee a couple of weeks ago. I hope this is sturdy. If plastic, I hope it does not break down in the sunlight.
    Rate this comment: 12345
    • Hail Stones
      Guest (D Van B) on 04/25/2006 at 12:00 AM
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      Same here in Indianapolis... busted a lot of windshields, dented metal... not sure if any solar system could survive that, though, so doubt it's a competetive disadvantage.
      Rate this comment: 12345
    • Hail Stones
      Guest (T De W) on 04/25/2006 at 12:00 AM
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      Not many non-commercial systems would/could survive those direct hits.
      Rate this comment: 12345
    • [no subject]
      Guest (ken novak) on 04/25/2006 at 12:00 AM
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      Most solar cells today face this issue, as they are encased in glass.  The glass is specified to survive heavy storms, like car glass or skyscraper glass.  It can break, but it takes a "disaster" level storm.
      Rate this comment: 12345
    • Stainless Steel Mesh 1 or 2 feet above the glass
      Guest (DSMatthews) on 04/26/2006 at 12:00 AM
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      1
      Just add a fine stainless steel mesh above the glass, it will deflect (bounce) or chop up and decelerate the incoming stones.

      :-) Dan.
      http://dan.3-e.net
      Rate this comment: 12345
      • steel mesh not a good idea
        Guest (peter segaar) on 04/28/2006 at 12:00 AM
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        meshes will, whatever their diameter will be, shed linear shadows onto your photovoltaic material. Not a good idea. Power and energy loss will be dramatic, since it has been shown that linear shadows can dramatically reduce output of solar panels. Most dramatic certainly in systems with cells coupled into series and modules coupled into series.
        Rate this comment: 12345
        • steel mesh not a good idea if thinck and close
          Guest (dsmatthews) on 07/13/2006 at 12:00 AM
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          Try a fine mesh up high and I thing in practice you may find that it works well enough and that there is  not a sharp linear shadow cast from it.
          Rate this comment: 12345
          • Re: steel mesh not a good idea if thinck and close
            Coreyjacob on 08/14/2007 at 5:48 PM
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            Any kind of mesh is going to reflect some sunlight away thus reducing the potential energy generated.

            Maybe there is a process similar to bullet resistant glass that could be applied a 1/2 inch or so above the actual panel to reduce or eliminate the shock of the hail directly against the panel and to try to eliminate any deflection of the sun's rays.

            By placing this bullet resistant like glass or plastic 1/2 inch or so away from panel would allow you to replace any cracked or damaged shields without having to replace the precious panel itself.
            Rate this comment: 12345
    • Re: Hail Stones
      Guest (Robert Loest) on 04/26/2006 at 12:00 AM
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      The PV panels I've looked at (BP Solar, Kyocera, Sharpe) all are guaranteed against hail damage. They are also at an angle, which would reduce the impact of hail a good deal.
      Rate this comment: 12345
      • Hail Stones
        Guest (Craig) on 04/27/2006 at 12:00 AM
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        I agree with Robert. I saw pictures from a guy in NM that had two cars ruined by baseball sized hail. He assumed his PV would be trashed, but it was totally fine...
        Rate this comment: 12345
        • Hail
          Guest (John Nicholson) on 04/27/2006 at 12:00 AM
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          The ones stated have been tested up to 1.25 inch hail.
          Rate this comment: 12345
    • Impact Test by UL
      Guest (Liang Ji) on 04/27/2006 at 12:00 AM
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      If the solar module bears UL1703 mark, it has been tested for an impact effect like following.

      A module or panel is to be subjected to a 5 ft-lb (6.78 J) impact normal to the surface resulting from a 2-in (51-mm) diameter smooth steel sphere weighing 1.18 lb (535 g) falling through a distance of 51 in (1.295 m). The module or panel is to be struck at any point considered most vulnerable.

      The pass criteria is that there shall be no accessible live parts, and breakage of the front material is acceptable provided there are no particles larger than 1 square in (6.5 cm2) released from their normal mounting position.
      Rate this comment: 12345
  • my question is being that silicon is found
    Guest (dan) on 04/25/2006 at 12:00 AM
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    in sand why is it so hard to comeby. Second of all , if other expensive materials are needed can it be massed produced enough to provide every house in the world with solar energy. A world where every rooftop has both wind and solar generation.
    Rate this comment: 12345
    • Silicon 4 Science
      Guest (Barry) on 04/25/2006 at 12:00 AM
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      The Silicon used in the manufacture of electronic compnents is man made, not raw and or refined (Chemistry.org). Other generating sources are not as efficient as solar, but if used all together it will free up any need for remote source provisions. Wind generator's, heat collectors for water, and solar panels are all just some of what an individual home can do, but what about grand scale generation for those who require tera watts, or giga watts? The answer is beneath their feet about a few thousand feet down. The largest natural battery in the world is the planet itself. and we have NOT even begun to tap into it's natural resource for electricity. The Natural Thermal Conduction Reclamation Process is the most efficient, but it is one they do not discuss in any circle. Why? Who knows?
      Rate this comment: 12345
      • Barry - Silicon 4 Science
        Guest (Inquiring jv) on 04/25/2006 at 12:00 AM
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        Keep asking.  Don't stop....you may be 'on' to something!!
        Rate this comment: 12345
        • Silicon 4 Science - To answer your question
          Guest (Jonni Blaze) on 04/25/2006 at 12:00 AM
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          Think about it...
          Do you really think the Power companies - or for that matter - the Govt - would like for us to be free of the grid ??

          The power companies want our money
          The Govt wants to control us.
          Working Together they both get what they want...

          That is why there is no REAL tech breakthroughs in eletrical energy generation.  That tech gets squashed.
          Rate this comment: 12345
          • time warp
            Guest (joey) on 04/25/2006 at 12:00 AM
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            your incorrect paranoia is utterly astounding.  new breakthroughs in science are made all the time, and many get to market.  if you feel a little oppressed, i wouldn't say it's because of anyone squashing ideas. 
            Rate this comment: 12345
            • geothermal power
              Guest (dinther) on 04/25/2006 at 12:00 AM
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              You mean Geothermal power right? Very common here in New Zealand.  See  http://www.nzgeothermal.org.nz/geothermal_energy/education/wairakei.asp

              Are you telling me they don't use this in geothermal area's in the US?
              Rate this comment: 12345
              • geothermal power
                Guest (John Nicholson) on 04/27/2006 at 12:00 AM
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                For us here in the US geothermal power has been costly. And, not much on the number of hot spots. The best way to use geothermal power here is as a heat sink as with a heat exchanger.
                Rate this comment: 12345
          • Paranoia
            Guest (Lan Mandragoran) on 04/25/2006 at 12:00 AM
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            What's really going to happen is not what you're imagining. You're thinking that everyone is going to run out and buy PV cells and put them on their roofs and then no one will need the power company anymore. Turns out what will happen is that some people will, and some people won't. And for now, even the people who will buy them are going to still need power on rainy days, and they'll still draw from the grid. Eventually though, what'll happen is that the power companies will no longer have to produce power, it will be generated by the people, but the power company will still have to be there to support the power grid so that all those people who don't run out and buy their own PV cells can get powered by the rest of us who do go out and buy them. So the money from those people will go to the power company, who'll take a little for maintaining the grid, and the rest will go to you who've made it. Your paranoia is entirely misplaced.
            Rate this comment: 12345
          • Duh
            Guest (Maury) on 04/26/2006 at 12:00 AM
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            > Do you really think the Power companies -
            > or for that matter - the Govt - would like for
            > us to be free of the grid ??

            Of course! Geez, you think they LIKE paying millions on millions of dollars to deliver a product to your house, and not make a penny doing it?! Reducing delivery costs improves their bottom line, trust me, if they could get people off the grid, they'd do it. It's not like you'd stop buying the product, after all, you drive TO the gas station to get their product.

            > The Govt wants to control us.

            I hope your tin foil helmet is in good working condition. Meanwhile for those of us who live on planet Earth, buying a few compact florescent lights is something that actually helps.

            Maury
            Rate this comment: 12345
      • Solar only true renewable source of energy
        Guest (mas) on 04/26/2006 at 12:00 AM
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        Geothermal energy, though quite plentiful, is not renewable. When the inner heat from the Earth is exhuasted, the carbon cycle will be interrupted and life on Earth will gradually die out since carbon will no longer be recycled and expelled by volcanos. Fortunately, you would have to reduce the energy in the mantle by a tremendous ammout before effects are seen.
        Rate this comment: 12345
        • Yes but the sun is going to burn out someday
          Guest (Eric) on 04/26/2006 at 12:00 AM
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          so we'd be better off harnessing the gravitational energy of the black hole at the center of the galaxy.
          Rate this comment: 12345
        • No true renewable source of energy
          Guest (John Nicholson) on 04/27/2006 at 12:00 AM
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          The sun will also expand and eat the earth. Earth will gradually die out since the global warming will be more than carbon fuels. Fortunately that will be in about 5B years. So no by your statement there are none that are renewable. So, you need to learn that words do have meaning in the present tense. Renewable means natural energy that does not cause waste.
          Rate this comment: 12345
    • my question is being that carbon is found
      Guest (JJK) on 04/25/2006 at 12:00 AM
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      in even more places than silicon, why are diamonds so hard to come by? 

      It must be a conspiracy by The Man to keep us down somehow.
      Rate this comment: 12345
      • Re: my question is being that carbon is found
        Guest (ss) on 04/25/2006 at 12:00 AM
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        Diamonds aren't that rare. They are just marketed very well. Google DeBeers conspiracy.
        Rate this comment: 12345
      • why is aluminum so cheap
        Guest (mike) on 04/26/2006 at 12:00 AM
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        It's about as useless as sand as an ore and consumes a lot of energy to refine.
        Rate this comment: 12345
        • Cheap aluminum
          Guest (ted) on 04/26/2006 at 12:00 AM
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          Aluminum manufacturers are usually ble to buy electricity very cheaply.
          Rate this comment: 12345
          • they certainly can
            Guest (peter segaar) on 04/28/2006 at 12:00 AM
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            in my country (Netherlands) the big alu melter Pechiney sits on the neck of our only nuclear reactor (that the guv boys decided NOT to shut down, the b....s). Their contract with the nuke boys is top secret. What do you think they will pay for a kilowatthour?
            Rate this comment: 12345
      • Diamond conspiracy
        Guest (Paul Palmer) on 04/26/2006 at 12:00 AM
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        It's funny that you chose diamonds because the DeBeers Company of South Africa runs a well known conspiracy to keep diamonds off the market and the price high. They've been doing it for about a hundred years, and their tentacles reach to  Russia, Amsterdam and the US. Diamonds could be much more plentiful without their market control. So far as I know this only holds for diamonds.
        Rate this comment: 12345
    • Silicon loves oxygen
      Guest (Silicon chemist) on 04/25/2006 at 12:00 AM
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      It takes an enormous amount of energy to convince otherwise.  The various reduction processes used require enormous temperatures, and the high purity required for a solar cell requires multiple processing steps.

      One could argue that hydrogen should be easy to come by, as we have an ocean full of it.  Unfortunately, like silicon, it has already combined with oxygen.
      Rate this comment: 12345
      • Re: Silicon loves oxygen
        Coreyjacob on 08/14/2007 at 6:04 PM
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        This brings to mind the whole "Dust to Dust" calculations of solar. Whether it truly is renewable. The sun is only as renewable and efficient as the process involved in producing, using, maintaining, and destruction or recycling of the panels themselves.

        If the panels are not recyclable, then its not renewable. Eventually you will run out of a particular resource needed to produce them. Thus making the sun's renewable energy is mute. For the whole process is as strong as the weakest link.
        Rate this comment: 12345
    • Purification
      Guest (Paul Allen) on 04/26/2006 at 12:00 AM
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      Solar Cells are made starting from silicon of extremely high purity.  Trace impurities interfere with the photoelectric effect.  Removing these impurities takes quite a bit of electricity.  Indeed, a solar cell has to operate 15-20 years before it generates as much electrial energy as was used to manufacture it!  This is the principle reason solar cells are not cost effective.
      Rate this comment: 12345
      • Energy payback
        Guest (Carl Lenox) on 04/26/2006 at 12:00 AM
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        This is absolutely untrue.  Many life-cycle studies have been done on this issue.  PV modules take 2 to 5 years to generate the amount of energy required to manufacture them.  The biggest contributor to the energy intensity is the aluminum frames.

        Silicon for solar cells (and semiconductors) is currently very expensive for two reasons.  First as noted, it needs to be very high purity.  Second is simply supply and demand.  Silicon demand has skyrocketed as PV has taken off.  Sometime this year, the PV industry will be using more silicon than the rest of the semiconductor industry behind.  This took polysilicon manufacturers by surprise.  Polysilcion plants are capital intensive and take a couple of years to come on line.  So, right now there is a shortage.  Most likely, as plants come online over the next coupel of years, there will be overcapacity for a while and prices for polysilicon will fall dramatically.
        Rate this comment: 12345
        • Meant to say
          Guest (CL) on 04/26/2006 at 12:00 AM
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          "Sometime this year, the PV industry will be using more silicon than the rest of the semiconductor industry COMBINED."
          Rate this comment: 12345
      • Re: Purification
        Guest (Robert Loest) on 04/26/2006 at 12:00 AM
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        The payback can be much shorter if you equate dollars with energy. Newer PV panels are made out of silicon wafers unsuitable for semiconductor needs. Newer processes can also manufacture it cheaper. But in the US. tax incentives have simply pushed up the cost by the amount of the highest incentives. The exact same panel in Europe will cost half as much as in the US.
        Rate this comment: 12345
        • US v Europe panel cost
          Guest on 04/27/2006 at 12:00 AM
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          That is not true. See
          http://solarbuzz.com/
          Rate this comment: 12345
          • Re: US v Europe panel cost
            Genesis on 11/11/2008 at 10:57 PM
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            It is too...I just called. Hey, the issue is energy self reliance. Would you rather we remain dependent on OPEC?
            Rate this comment: 12345
        • Re: Purification
          Coreyjacob on 08/14/2007 at 6:12 PM
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          The true key is not the Dollar itself but how much of a particular energy intensive process you use.

          If you could some how minimize or eliminate the aluminum for example then the payback for energy will be shorter in that its less energy intensive to produce. The key is finding less energy intensive and renewable process to make it sustainable in the end. Through minimizing resource + recycling
          Rate this comment: 12345
    • Re: my question is being that silicon is found
      Genesis on 11/11/2008 at 10:55 PM
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      sILICOM IS VERY COMMON IN THE sAHARA AND gOBI DESERTS. In fact my friend Muamar has lots of problems clearing the city after sandstorms. Besides if they could be manufactured w/o leaving a carbom footprint, then, why not?
      Rate this comment: 12345
  • Typical Layperson article
    Guest (Harvey) on 04/25/2006 at 12:00 AM
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    There is not a word in the article about how the device is actually constructed. This is supposed to be MIT "Technology" review, but it appears to be written for investors and consumers. How does a hologram concentrate light from different directions and of different frequencies onto strips which appear from the picture to be lying next to them? Not a hint of a technological explanation! Like most of the articles in this magazine.
    Rate this comment: 12345
    • solar panacea?
      Guest (kitk) on 04/25/2006 at 12:00 AM
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      There are always problems with dispersed energy generation. Silicone is indeed incredibly common--and unusable in its natural form. It requires large factories and a hell of a lot of energy to be turned from sand to pure silicone. Solar panels are relatively fragile, and would not easily withstand severe storms. Geothermal sounds great, but unless you have a large circulating body of fluid, like hot water, you will only get a little energy before you have chilled the rock around your well. This is why we have power plants burning coal: they work well at our technology level.
      Rate this comment: 1234