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Roll-Up Solar Panels

Continued from page 1

By Prachi Patel

Thursday, June 04, 2009
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Other companies, notably Heliovolt and Nanosolar, are in a race to make thin-film panels using copper indium gallium selenide (CIGS) cells. These have shown efficiencies on par with crystalline silicon and can be made on flexible substrates. In comparison with amorphous silicon, CIGS is a relatively difficult material to work with, and no one has been able to create low-cost products consistently in large quantities, says Ryan Boas, an analyst with Photon Consulting, in Boston.

Building integrated photovoltaics (BIPV), especially rooftop applications, would be the biggest market for flexible PV technology, Boas says. That's because flexible products are inherently very light, in addition to being quick and easy to install. "Imagine carrying a roll of flexible product on the roof and unrolling it," he says. "Workers are already used to unrolling roofing material."

But there are hidden risks and costs associated with BIPV, Schmidtke says. "BIPV is often touted as low cost," she says, "but in actuality, you've got greater risk in terms of a watertight system [for roofing materials] or fire risk, and that increases total installation cost." However, BIPV does have the advantage of being more aesthetically pleasing, which is important to consumers, she says.

So far, Xunlight has raised $40 million from investors. In December, the state of Ohio gave the company a $7 million loan to speed up the construction of a 25-megawatt production line for its flexible solar modules. The company expects to have commercial products available in 2010.

Tags

energy nanocrystals photovoltaics solar thin films

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Comments
  • price
    How tough is it as far as walking on it or cleaning it, like scraping snow or scrubbing oily soot off?  Where I live, we get dry desert sand storms and a lot of lighting.  How would such a thing covering a roof act with heavy static electricity?  Would my house act like a big capacitor?  It is a hard life as a roof in many cities. 
    Rate this comment: 12345

    StupidPeasan...
    06/04/2009
    Posts:35
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    • Re: price
      Walking on it (carefully, with proper shoes) is ok.  Cleaning it with water jet is ok - has to be done at least once a year - the uneven plastic surface is a magnet for soot, dust, etc.   In cold climates, it is a magnet for snow (unlike tilted glass panels).  Scraping and scrubbing is not recommended (may lower efficiency and even damage the laminates).

      Read here:
      http://www.marcegaglia.com/building/pdf/man_mont_Solar_EN_magg09.pdf

      Don't expect these things to last 20 years (Unisolar's warranty is 20 years at 80% rated power, but it likely won't hold, based on some data by NREL)
      Rate this comment: 12345

      ECD Fan
      06/07/2009
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  • roll to roll as differentiator?
    United Solar and Stan O were proud to be roll to roll many years ago, no? Not sure why the author implies that this is the advantage for Xunlight over United Solar Ovonic?

    I remember an old video on PBS highlighting Ovshinsky and Energy Conversion Devices not only for the NIMH and Hydrogen, but for the roll to roll thin film solar incorporated into roofing materials.  On top of that, I am quite sure that Uni-Solar's efficiency is higher than the 8% mentioned for Xunlight.

    This seems like a copy cat company to me, not innovation unfortunately.

    http://www.uni-solar.com/uploadedFiles/Uni-SolarTechnologyandManufacturingProcessAppendix.pdf

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    designbus
    06/04/2009
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    • Re: roll to roll as differentiator?
      I agree with Designbus, this seems like another company trying to develop a roll out solar cell. Unfortunately, it has not caught on yet. WHY?
      I surmise that the Price per square foot is too high. And price per generated KW hour is too high.
        A smart business owner, or home owner, would go for this, but the time to recoup the investment of Solar Celling your Roof, should be less than 2 year, especially, in this bad economy.
        So imaging a electrical saving of $300 to $400 per year for a normal house, returned over two year, would at max limit the initial investment amount $1 to $2k. If they could manage to reduce the price to this level, I would image solar cells being ubiquitous. Currently I think solar celling a house cost around $10K to $15K which is way to high! 
        Hence, I am most interested in manufacturing cost reductions, unfortunately this article does not mention anything about cost : (
      Next time tell us how much per square foot!
      Dr. Brian Glassman
      Ph.D in Innovation Management from Purdue University.
      Brian.Glassman@Gmail.com
      Rate this comment: 12345

      briang1621
      06/06/2009
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      • Re: roll to roll as differentiator?
        briang1621:  Photovoltaics is NOT a roofing material, despite what certain manufacturers, consultants, and article authors may try to claim!  It is an alternative way of generating electricity, and thus its "cost" should be measured in price per Watt, or more precisely, in price per KWH delivered over the warranted life of the system.  But if you want price per sq ft, take the lowest theoretical, $5 per Watt, all-in system cost for Unisolar's laminates, for example, and note that they deliver 4-5 peak Watts per sq ft, and you will come up with $20-25 per sq ft, at best, or 5x-20x more expensive than a roofing material.

        But that's not the reason why it has not "caught up" yet.  The reason is that the PV laminates are a very expensive and risky way to generate electricity. You can find the economics details here:

        http://ecdfan.blogspot.com/2009/05/unisolar-dilemma-not-selling-or-selling_27.html

        Putting tilted glass panels on the roofs results in a cheaper way to generate electricity than trying to glue laminates, using today's prices.  In addition, the dark-blue laminates (Xunlight's exhibit a more reddish tint) heat up the roof, leading up to 20% increase in HVAC electricity costs in certain cases (while glass panels cast shadows and improve air ventilation, thus cool the roof).

        Don't hold your breath on manufacturing cost reductions for the PV laminates.  Mr. Deng and company have been working on that for 20 years.  The results have been dismal ($2 per Watt cost of manufacturing, at 100MW+ production level, with below 7% efficiencies on panel-level).  On the other hand, First Solar's cost of manufacturing are below $1 per Watt, and their panels are 11% efficient.  Some crystalline guys are making big progress on costs as well, as their raw material has become abundant (and they are 14%+ efficient).

        And, by the way, a $2K system, at today's prices, even after all rebates and tax incentives (if you are lucky!), will probably get you just 500 Watt peak worth of laminates, which will save you less than $150 a year in electricity costs.
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        ECD Fan
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    • Re: roll to roll as differentiator?
      designbus:  Well guess who worked with Mr. O on those roll-to-roll machines and processes those many years ago  - it was Mr. Deng, of course.

      You (and the article's author) are wrong about efficiencies.  Take a look at the table below, with numbers taken directly from official panel datasheets :

      http://spreadsheets.google.com/ccc?key=rN3EmdvOo2Lw5bs_fSJ-XxA&hl=en

      As you can see, Xunlight's efficiency is below 7%.  And so is Unisolar's.  Despite all those hundreds, if not thousands, of man-years wasted in improving the roll-to-roll process, it remains high-cost ($2 per Watt) and results in INefficient product (compare to 11% for First Solar, and 15% and over for crystalline). 
      Rate this comment: 12345

      ECD Fan
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      • Re: roll to roll as differentiator?
        Nice. I did not know that regarding Mr. Deng. Also, I must admit that the words "quite sure" were probably an overstatement when speaking of the efficiencies. I had utilized a chart found via google (see link below), that I'd seen for the first time as I was writing the comment. Obviously not the best source.

        http://www.wikinvest.com/stock/Energy_Conversion_Devices_(ENER)

        I suppose my motivation for commenting in the first place was less to argue that ECD is somehow superior to Xunlight (or First Solar for that matter) and more that they had been doing roll to roll for years while the author seemed to be implying that Xunlight was blazing the trail.
        Rate this comment: 12345

        designbus
        06/09/2009
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  • [no subject]
    Here are some problems with this article:

    1. Xunlight's product is a poor choice for notebook chargers, given its low-efficiency.  Chargers with monocrystalline cells are most durable and take 3x less area. Next best choice are CIGS-based cells.

    2. a-Si cells are not cheaper than crystalline cells, especially after properly adjusting for the low-efficiency that results in higher balance-of-system costs. a-Si cell do not use polysilicon - they are made directly from silane (or disilane) mixtures - in other words, the a-Si manufacturing is essentially vertically integrated, and thus, quite expensive.  Unisolar's current cost of goods manufactured is $2 per Watt, at 100MW+ annual production run rate.  Adjusted for efficiency, that makes it over $2.40 per watt (or above crystalline's cost of manufacturing).  Xunlight, of course, has no no scale, thus, their costs are higher than Unisolar's, and thus, they probably won't survive the current downturn.

    3. Xunlight's XR-36 "panel" is rated 330 Watts indeed, but it is just 6.9% efficient on module-level (divide the rated watts by the total area of the laminate in square meters, and multiply by 10).  Sunpower's SP-315 module with the same area will be rated 2.8x higher, or over 920 Watts (not just 740 Watts).

    4.  Mr. Boas from Photon Consulting is wrong when he says that the laminates are "quick and easy to install."  Real world data indicate that the hit to balance-of-system costs from the low efficiency of the laminates outweights any savings from lack of racks, easier handling, etc.  As a result, Unisolar's laminates balance-of-system costs are about $3.50 per Watt, while crystalline's are about $2 per watt.  All-in system costs are $6.50 per Watt for Unisolar, and below $6 per watt for crystalline modules.  First Solar is even promising $3.50 per Watt all-in costs.

    See: http://ecdfan.blogspot.com/2009/05/is-350-per-watt-all-in-reality.html


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    ECD Fan
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