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Pliable Solar Cells on a Roll 241

klevin writes "New Scientist is running a story on someone else who's developed thin, flexible, photovoltaic cells: 'The thin and bendy solar panels can be stuck to fabrics, sheets or backpacks and promise a go-anywhere electricity supply.' Whatever happened to those sheets of solar cells that some university here in the US developed several years back? As I remember, the concept was that they could be draped across roof-tops and whatnot. Never heard anything after that." We had post about solar building clothing last year.
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Pliable Solar Cells on a Roll

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  • Hmmm. (Score:2, Insightful)

    by krymsin01 (700838)
    Would be good to use as a solar sail, I bet.
    • Not really (Score:3, Interesting)

      by Nomihn0 (739701)
      If I understand solar sails correctly, this is not how they work. Instead, they utilize the combined force of billions of subatomic particles radiated by stars hitting a parachute shaped foil to tow a capsule. This is why they are made to be exceptionally lightweight and large in their surface area.
      • Re:Not really (Score:2, Informative)

        by krymsin01 (700838)
        Yes, you are correct in that, but if you made the sail out of a large, lightweight, flexible solar panel, you'd be generating electricity and momentum.
        • Weight is the key... (Score:3, Informative)

          by The Kiloman (640270)
          Usually people imagine solar sails as being made of a very VERY thin film,on the order of a few micrometers thick... the point being that there's very little additional mass created by the sails themselves since you need so much surface area to create any appreciable force. Also, the less mass that's used for the sails, the more mass that's available for payload (or just plain not there, which means greater acceleration).

          Here's a few links (thanks Google and the obligatory Wikipedia):
          A geocities-looking []
        • you'd be generating electricity and momentum.

          you'd be generating electricity at the cost of momentum. If the sail absorbs the photons to make electricity it can't reflect the photons to make motion.

      • Re:Not really (Score:2, Informative)

        by Anonymous Coward
        Oddly enough, not so much the force but the momentum. And not subatomic particals so much as light. Stars appearently make a lot of light. And that's why solar sails, as opposed to cells, are reflective. The radiation pressure equation would probably provide more insight into this should you wish to investigate further.
      • Re:Not really (Score:3, Insightful)

        by lightsaber1 (686686)
        Holy Crap! Am I the only one that read this as a joke? Geez, some people take things way too seriously...and whoever modded this "Insightful" as opposed to "Funny" needs to grow a sense of humour.
    • um, no it wouldn't. i can't believe you got modded up insightful.

      solar sails need to be incredibly light and (as a consequence) thin.

      solar sales work on light pressure not by converting light to electricity to drive an engine.
    • Re:Hmmm. (Score:4, Interesting)

      by The_Dougster (308194) on Sunday December 19, 2004 @05:32AM (#11129072) Homepage
      Solar sail? Try relativity rocket.

      Just use the solar cells to power up a linear accelerator and shoot nuclei out the back at near the speed of light. If you can get 0.999c from a nucleus you get a tremendous thrust for one little atom. Remember, F mA when you approach the speed of light. Relativity rockets (super ion engines) are probably the best means of propulsion where electric power is plentiful but mass is dear. I'm sorry, but that tiny momentum of a photon is so small it is pathetic. Granted you get 2x boost for reflection vs 1x boost for adsorbtion, but 2 x 0 still equals 0. The only way to practically get around in space is to shoot nuclei out the back of a rocket engine at the speed of light.

      • The only way to practically get around in space is to shoot nuclei out the back of a rocket engine at the speed of light.

        The problem is that energy efficiency of space drives (i.e. how much kinetic energy ends up in the vehicle, rather than the exhaust) is inversely proportional to the speed of the exhaust.

        So, nuclei at 0.999c are very much *less* energetically efficient than chemical drives or normal ion drives; atleast unless you intend to travel at *very* high speeds- as in interstellar travel rather

      • How do you propose we get something like this, which is usually a few kilometers long, into space? The linear accelerator I mean, it's not like one 100 metres long will get you atomic nuclei traveling at 0.999 of lightspeed. The things are usually a few kilometres in size.

  • by aheath (628369) * <<adam.heath> <at> <>> on Sunday December 19, 2004 @02:09AM (#11128669)
    I wonder if there are other applications that make more sense than clothing that can charge a cell phone.

    I think this type of material could be very useful to provide electricity in places that do not have access to a reliable electrical grid.

    How many watts are needed to run a a phone, a refrigerator, a radio or a computer?

    • Quite a bit more than I would think can be powered by embedded solar cells. It is hard enough for a regular solar cell to power anything with somewhat demanding electricity usage. Besides the fact that solar energy is not exactly the 100% uptime 24h solution.
      • it isn't 24hr, but it is a 100% uptime solution. Many people think that you need direct sunlight, but if you can see, then there's enough light hitting the panels to generate some electricity. It may not generate as much as you'd get when the panels are in direct, full sunlight, but you get something.
        • "if you can see" - well, technically, yes, but the dynamic range of the eye is amazing. The difference in the amount of energy you could get in dim light (say, just enough to read by) and the amount in full sunlight is so enormously large that the former might as well be zero. Even in fairly good light (e.g. under a 60W bulb 2-3 feet away) the amount of energy you can practically recover is very small (enough to run a calculator, not much more). Even with full sunlight and high efficiency, you still need

    • I think this type of material could be very useful to provide electricity in places that do not have access to a reliable electrical grid.

      Solar cells are already used in lots of applications that don't have access to an electrical grid, reliable or not. Pliable solar cells might be useful in more applications, but the ones we have now are used quite a bit.

      What applications, you might ask? `35 mph school zone' lights (it's easier to add solar cells than to run wires.) Remote creek monitoring stati

      • Well, my laptop power supply is rated at 65W.
        It takes about as long to charge the battery (while still using the computer) as to exhaust the battery so i'd imagine the power consumption of the laptop itself is about half this.

        Regarding the mobile phone. My charger has a rating of less than 7W, and i usually need to charge it for about 2.5 hours every 3 days. This is very manageable with solar cells (you have 72 hours to accumulate 21 watt-hours of energy).
      • that reply is so American it's not funny. []

        for non-US readers, we have nifty governmental regs that require yellow energy consumption labels on the side of most kitchen appliances, that include likely annual operating costs, to allow the consumer to make a better informed choice...

  • The new Apple fashion: instead of black shadow people in their iPod advertisements, everyone is now covered with solar panels. (This might actually help the batter life, though, so it's not a total loss.)
  • WARNING (Score:3, Interesting)

    by Dash'n'SlashDot (841636) <<moc.liamg> <ta> <drazzahmilc>> on Sunday December 19, 2004 @02:15AM (#11128688) Homepage
    God, solar panelling on the clothes. try to imagine the warning labels they would put on thee things: WARNING! DO NOT USE WHILE BATHING OR WHILE HAVING SEX. ... Don't laugh. You heard it here first. Expect it on your self-heating winter coats next year.
    • Normally winter occurs because there's less sunlight than usual. I don't think they're going to be producing your imagined self heated clothing through solar panels any time soon.


      I think that warning is pretty redundant for most people around here...
    • "Expect it on your self-heating winter coats next year."

      Uh, we already have those. They're called "dark colors". Direct light to heat conversion. Very efficient.
    • WARNING! DO NOT USE WHILE BATHING OR WHILE HAVING SEX. ... Don't laugh. You heard it here first.

      True, I did hear it here first.

      But I couldn't help myself -- I laughed.

    • Self-heating winter coats... so they take photons, convert it to electricity then convert it to heat.. ingenious.

      or you can just wear a black shirt and skip the whole electricity part.
  • by Anonymous Coward
    The poster might have been thinking about Iowa Thin Film Techologies []...
  • by sahrss (565657) on Sunday December 19, 2004 @02:20AM (#11128703)
    To address some of Klevin's confusion, since I've been following solar panel advancements:

    Thin, flexible cells have been around for a while. One reason they haven't caught on heavily is because they're nowhere near as 'powerful' (efficient at conversion) as hard panels. Did a quick search (don't take this data *too* seriously, but it represents what's normal); compare panels from these two pages:
    Flexible []
    Solid []

    Specifically, compare "Unisolar 32 watt flexible solar panel" from the first link to "Shell ST40 thin film CIS 40 watt solar panel" on the second. The flexible panel is 940 sq. inches and 32 watts, while the solid panel 663 sq. inches and 40 watts. Big difference in watt per area.

    I ended up choosing a big solid one to fit in the rear dash of my car; flexible would have been easier to deal with, but it won't fold, and produces less power. (I use the panel in my car to power my laptop/cell phone combo while camping and stuff, it's very cool and gets a lot of questions from random interested people!)

    Here's another chart to compare the two: Product Page []
    Tried to find an efficiency rating chart comparing the two types, but no luck. The numbers are out there somewhere...
  • sweet! (Score:2, Funny)

    by Cannedbread (841645)
    i live in oregon and i really cant wait to get a solor powered raincoat. oh wait
  • Cheap solar panels (Score:2, Insightful)

    by Squalish (542159)
    Screw clothing to charge cellphones, etc. I can't think of a more petty use.

    The major impact of this tech has nothing to do with its portability/flexibility. The article estimates that the price for a final process fab will be about 1 euro per watt, compared to a highly competitive market which has so far only produced 5.6 euro per watt glass panels.

    Simply put, this would make photovoltaics as an energy source an order of magnitude more competitive, if the process is scalable.
    • by Squalish (542159)
      Okay, was reading the wrong data, that was peak price, the lowest prices one can find are around E2.66 per watt for crystalline + E3.15 for thin film.

      Still, 1 euro per watt would make a HUGE difference in the viability of solar.
  • I don't care what anyone says.

    Now matter how pliable or environmentally friendly, solar cells are not good on a roll. They taste absolutely nothing like butter, and quite frankly, I find them barely palatable.

    Don't the editors try this these things themselves? This is as bad as that " 41&tid=126" story. Trust me, those things taste absolutely nothing like fruit-rollups.
  • by thorpie (656838) on Sunday December 19, 2004 @02:49AM (#11128769)

    They quote 7% efficiency, 1 euro per watt.
    Full sun is 1000 watts/sq metre, so with 7% efficiency we get 70 watts/square metre, so it has a cost of 70 euros/sq metre or, at 1.33 euros to the dollar, about $US52.60/sq metre.
    Cover a 10 * 4 metre area of roof for $2,100 and get enough energy, in the middle of summer, to boil your 2 kw electic kettle all day.
    At 12c per kwH for electricity, @ 2.8 kw * 6 hours/day * 365 days/year gives a cost saving of $735 pa, or a repayment of the $2,100 capital in 3 years

    Are these numbers OK?

    At this price will it be practical to disconnect from the grid sometime soon?

    • I think you 1.33 US dollars to 1 euro.
    • by drphil (320469) on Sunday December 19, 2004 @06:28AM (#11129200)
      Although there is nothing wrong with your calculation per se, there are a lot of costs it doesn't include, so it is low by quite a bit. The 1 euro per W (peak Watt or average W - article doesn't say) is only the cost for just the solar cell at high volume manufacturing. At that point you are still quite a long ways from installing this on your roof cost-wise. You still have to put the solar cell in a module, then install it in a panel, then install the panel on your roof along with a rectifier (since your house expects AC) plus other equipment and power storage if you want to be competely off-grid - there are costs, of course, each step of the way.

      The rule of thumb I came across when I was studying the econ of solar cells ~18 months ago was that for thin film cell solar to be viable (without govt subsidy) it had to be manufactured for $1/pW (or one euro, depending on exchange rate) and had to have at least 10% efficiency. If the 10% efficiency is not met then the downstream costs eat you alive because you have to install so much more area of solar cells to get the required power.

      The current advances in flexible solar have been excellent and the solar market is growing at ~30% (although still >90% c-Si cells), but unless you are willing pay a price to be "green" or your govt gives you a fat subsidy for installing the solar power it will take you many years to repay your capital - on the order of 10 or more if you currently have ready access to the power grid. If you are remote from the grid, solar is actually a great deal cheaper today - but by using Si-based solar which is manufactured on relatively large scale today and has 15% efficiencies versus thin film.

      Govt subsidies are still going strong in Japan - Germany is wavering. With G(lobal) W(arming) Bush in office the increase in solar in the US is going to be from the Eco-minded willing to take a bath $$-wise or off grid applications - well, there are also cats who are pretty good at utilizing passive solar power.
      • well, there are also cats who are pretty good at utilizing passive solar power.

        I'm going to have to agree with drphil on this one. I myself have three cats, and they're extremely well versed at passively utilizing the solar power entering through the window.

      • then install the panel on your roof along with a rectifier (since your house expects AC)

        You don't necessarily need to run much or any through a rectifier and lose power that way.

        Forty-five years ago my parents had a 12V DC generator, they still have a pile of 12V bulbs and other bits. 12V DC lighting has improved a lot since then, and there are a lot of appliances (including refrigerators) that run off 12V DC. Your computer lives on 12V, some LCD screens can too. Buying a whole lot of stuff that runs o

    • No, they're not. While insolation at 1AU from the sun is indeed about 1300 watts per square meter, that, or anything approaching it, can't be used as an average insolation value *anywhere* on the earth's surface.

      In Albequerque, New Mexico, the yearly average (taking into account both day *and* night, when the sun doesn't shine at all), is actually only about 250 watts per square meter. So you're already off by a factor of 4. Move to a city like Seattle, which is a lot farther north (less sunlight) and w
    • Let's say it's 1 Euro/watt. That's about $1.33 USD/watt, or about $1,330/kW.

      The next factor to consider is the solar insolation [] for your area. This tells you how many hours of direct sunlight you get, for your area, each day. In my case, the annual average is about 4.5 hours / day.

      At that rate, 1 kW of photovoltaics will give me about 4.5 kWh of electricity, per day, on average.

      Also in my area, electricity is about 7 cent/kWh. Consequently, that 1 kW PV array will save me about 31.5 cents/day, on ave
  • Without even glancing at the article (this IS /.) I'm curious how this is different than the rollable flexible solar cells that have been on the market forever.

    I can buy them at canadian tire, thats how common they are. Product # 11-1575-0 for example. (might neet to enter a postal code, v1p1c7 works.)

    Maybe they are more efficient or something? These seem about the same as a rigid solar panel for the size. More expensive though obviously.

    FINE, I just looked at the article..seems the only advantage is th
    • FINE, I just looked at the article..seems the only advantage is they are expected to be dirt cheap. I've heard that before. I'm still waiting to wallpaper my house in transparent OLED film :)

      I've got my north wall wallpapered with an OLED screen broadcasting a white image and my south wall wallpapered with solar panels to catch it all.

      I hereby claim prior art for all the future perpetual motion/infinite energy machine creators who attempt to patent my brilliant idea.
  • As I remember, the concept was that they could be draped across roof-tops and whatnot. Never heard anything after that. e fault.asp []

    SSP as mentioned on Slashdots pior story for having solar "denim" has small flexible solar panels avaliable now in Canadian Tire. Not that this helps those of you not in Canada... But you can buy them now.
  • Any reasonably useful photovoltaic system is going to need about 1kW output under typical conditions. So with this material, for around $1000 you can generate maybe 50 cents worth of electicity each day. Obviously you aren't going to get rich by selling power back to the grid with a scheme like this but 1kW of totally free power would be kind of nice to have.

    I always thought that a cool thing to do would be to use the excess electricity from PV cells to crack water and make Hydrogen gas rather than goofing

    • Yes, you will get rich. If a $1000 investment yields $0.50 per day worth of electricity on average, then that results in $182.50 per year in revenue. Assuming no maintenance, land, installation, or other overhead costs, you are earning 18.25% yearly on your investment. It would be like printing money!
      • Yeah, now that you mention it, I believe that it used to cost around $5000 for a 1kW PV array. This is a 5X price drop in capital equipment costs. If you set up shop like in New Mexico, you might make more like 90 cents per day's worth of power also because of the increased solar mean day index, and desert land in NM is probably super cheap.

        Hooking up to the grid is both tricky and lossy. You must feed in a synchronous AC signal which is in phase with the grid. Typically you would use a DC->AC motor/gen

    • Any reasonably useful photovoltaic system is going to need about 1kW output under typical conditions. So with this material, for around $1000 you can generate maybe 50 cents worth of electicity each day. Obviously you aren't going to get rich by selling power back to the grid with a scheme like this but 1kW of totally free power would be kind of nice to have.

      There are two key price points;
      Cheaper than a consumer can buy electricity,
      and cheaper than the electric company can make electricity.

      From the f

  • by dr.Flake (601029) on Sunday December 19, 2004 @05:03AM (#11129007)
    What amazes me is that all this investment time and "energy" is spent on cells that produce electricity.

    Whereas the collection of Heat is as simple as it can get, but rarely used.
    Though most mediteranian countries use solar heat for heating their domestic water, but that is about it.

    What i have in mind is the use of solar heat, collected during summer, to warm domestic homes during winter. (Thats where real amounts of energy (read CO2) are needed !)
    Water is an exellent storage container for heat and is dirt cheap.

    The only problem is where to store all the warm water. Probably the easiest solution would be to pump up ground water, heat it, and pump it back. (The ground is actually an exellent therman insulator!)
    Use the 1kW of solar energy from a couple of M2 of these cells to make water run through 100 m2 of cheap solar heat collectors.

    Now we are SAVING evergy.
    • by TheLoneCabbage (323135) on Sunday December 19, 2004 @06:35AM (#11129224) Homepage
      Most solar researchers in this veign are using Sodium Cloride (table salt). It has a much higher specific heat than water. Tends to be less explosive when heated to 600c (you really want to build your house on top of an aging steam boiler with the equivalent energy of dynamite?), and is even cheaper than water and dirt (water aint cheap where I come from)! When molten it's conduction of heat is so efficient you don't even need pumps, it's own confection currents do the work for you.

      Now you just need a near perfect insulator and your all set. (say an underground tank insulated with airogel)

      The real trick isn't in just heating homes though. It's also running things like ovens and stoves. For that your going to need a liquid that stays a liquid between -10c and 250c, without dangerous pressure build up, freezing, corroding or screwing up your pumps. (and it can't pollute the environment when it leaks)

      Once you can safely transport high temperatures 2-3 times boiling point, you can do some pretty amazing things. Like running your A/C from the heat well. (two sterling engines hooked up to eachoter in reverse) Water pumps, air tools, and electrical generators (40-50% efficient in sealed systems like sterlings, but much higher for open ended boilers. The trick as you put it is to avoid converting the energy from one form to another untill it's absolutly necesary.

  • I think solar power would be great for my home,

    It spends a lot of time out in the sun.
    But my clothing?
    I don't spend nearly as much time in the sun as my home does ;)

    -- The Dude
  • Yay! At long last! Mr Solar [] is a reality. :-D
  • From US companies, too. The current leader in thinness is PowerFilm flexible solar panels. [] Flexible panels have been available for years from Ovonics; they're widely used on boats. Some sailboats have solar panels in the sails.
  • Solar power? (Score:2, Informative)

    Several U.S. Companies now provide solar shingles, in fact, my company has two vendors that carry them, they're just not quite popular yet because they're still a tad pricey.

10 to the 6th power Bicycles = 2 megacycles