Solar Sails

Discussion in 'Boat Design' started by anton_mr, Apr 12, 2012.

  1. anton_mr
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    anton_mr Junior Member

    It's news from 2008 but I couldn't find a mention on this forum with a search tool.

    So there's a fairly new solar energy technology http://www.g24i.com/ which uses dye sensitized cell, thin-film to be certain.
    More about the technology http://www.g24i.com/pages,technology,73.html

    The potential for ship design is huge: the panels they make can be fit into sails and anywhere on the boat due to them being flexible, thin, having good resistance from water.

    Here's an experiment gone well with solar sail:
    http://www.g24i.com/press,2041-and-g24i-debut-first-solar-sail,129.html

    It's inspiring to say the least. Opinions?
     
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  2. Stumble
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    Stumble Senior Member

    I found the article about the film being applied to sails, but I couldn't find any follow up on either the boats project, or the manufacturers one.

    Fundamentally I am pretty skeptical though. Sails need to be incredibly robust to last even brief periods of time, and even more common materials really make poor sail cloth. In addition the weight added from the panels would significantly reduce righting moment, and add to the vessels instability.

    Finally since boats tend to have a huge demand for power as compared to their production capability the $/watt is less critical than the $/sq foot. This is a departure from land based applications, where the reverse is true because there is typically more space than money. I would be interested in reading more, but absent brag sheets at least I have to think the application is pretty marginal.
     
  3. BPL
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    BPL Senior Member

    Skeptical but following this thread.
     
  4. CDK
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    CDK retired engineer

    The absence of follow up is significant.
    Flexible photovoltaic products have been discussed here before, but it seems none of the proposed new technologies have reached the production stage.

    What people tend to forget is the wiring necessary to get the electricity where it is needed. If a solar panel the size of a main sail could be made and had an efficiency comparable with conventional technology , the weight of copper conductors would endanger the stability of the boat.
     
  5. Submarine Tom

    Submarine Tom Previous Member

    Opinion?

    Sure.

    Sails are already solar powered, by the wind!
     
  6. anton_mr
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    anton_mr Junior Member

    Well the mentioned company has reached the production stage as their website claims.
    As far as the weight of copper conductors go I don't know but still, things can be done to overcome that I believe. At least this is the closest I've seen to a good solution of solar energy in boats. It's a dream come true to have sails and engine combined with solar energy (or other source of energy) that will power the engine when needed therefore decreasing dependance on fossil fuels and decreasing costs of boat maintenance.
     
  7. anton_mr
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    anton_mr Junior Member

    Well, not to the top of their potential ;)
     
  8. CDK
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    CDK retired engineer

    I admit to being wrong, the G24i.com company has at least one real product: http://www.g24i.com/pages,outdoor-applications,64.html

    It is not really the printed on fabric type, because it has a substrate that makes it rather stiff, but nevertheless....

    Imagine such a breakthrough innovation stitched or glued to a sail of 30 sq. meters. Are sails that big? Yes, sometimes they are. The product measures 200x254 mm or roughly .05 sq.m., so there are 600 units of 50 grams on the sail, 30 kg total. With both sides of the sail done that way it is 60 kg., not counting the wiring.

    The wiring is not a significant factor here, because:
    The spec. sheet says they produce 70 mW at 0.1 sun, the intensity to expect from a sail that by nature is never facing the sun. That makes a total power output of 42 watts for a single sided sail, 84 watts for a double one, about the same as can be obtained from a real solar panel of .5 or 1 sq.m. facing the sun.

    Conclusion: an utterly useless invention.

    Also note that the company warrants their product for 1 year, because they know dyes bleach pretty fast and there hasn't been any thin film solar panel yet that retained its output power after being exposed to sunlight for one season.
     
  9. anton_mr
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    anton_mr Junior Member

    Thanks for the explanation, CDK.

    Yeah, I think their main purpose was to install such thin panels in different devices for recharging and small power output. I think I saw a concept of a cellphone with that thing somewhere. So any step in that direction is not useless but I see now that it's not likely to be applied for boats yet.

    It would be interesting to hear from someone who participated in that boat experiment they write about. They can't simply lie that it happened.

    Some time ago when I stumbled upon their website when searching for something in that area I wrote them a question about such sails and got this response:
    "Do you have specific power requirements for the sails on your boat?
    This will give us a better idea of feasibility."
     
  10. Submarine Tom

    Submarine Tom Previous Member


    Potential, PUN, I get it, funny...
     
  11. anton_mr
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    anton_mr Junior Member

    On a related note, do you reckon there is a possibility to use the sun energy that is reflected from the sea by installing panels on the hull? I don't think such panels exist yet, but theoretically, the disadvantage I can think of is that they will be exposed to a lot of damage.
     
  12. FAST FRED
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    FAST FRED Senior Member

    What people tend to forget is the wiring necessary to get the electricity where it is needed. If a solar panel the size of a main sail could be made and had an efficiency comparable with conventional technology , the weight of copper conductors would endanger the stability of the boat.


    The newer tech in solar panels uses a simple inverter on each unit to boost the voltage to 120v or up to 400v.

    Far thinner / cheaper wires to hook many panels together.

    Google "Home Power" magazine.

    FF
     
  13. CDK
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    CDK retired engineer

    Average total radiation from the sun is 1000 W/sq. meter; the best solar panels can harvest up to 20%. Reflection from the sea surface is no more than 10%, so a panel receiving the reflected radiation will collect 20 W/sq.m. Not very impressive!
     

  14. kerosene
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    kerosene Senior Member

    not quite relevant but anyway. I am about to start a cross country motorcycle trip that is largely on dirt and a lot of times in very remote areas. My bike has only electric start and draining battery because of any other issues (like trouble shooting any other engine problem) would mean being stranded.

    My buddy who climbs mountains and does such crazy things is lending me his 26W folding flexible solar panel. I can use it in an emergency to charge my bike battery if I just take a day of chilling out.

    Price is in hair over $300 range and folded size is like a medium sized notebook.

    No business in sails as the weight is significant for small size.

    I am not sure the copper wiring would weigh THAT much. Really it all boils down to voltage. Higher voltage can carry a lot of power with less current (smaller wire). Of course high voltages are other wise riskier.
     
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