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solar cell fail

Discussion in 'General Electronics Discussion' started by quantumtangles, Mar 30, 2013.

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  1. quantumtangles


    Dec 19, 2012
    After discovering that the resistivity of distilled water is enormous (about 2 megaohms) but that adding NaCl (salt) reduces the resistivity to a mere 2 ohms...I decided to try mixing various compounds together to check their photochemistry (if any) and electrical properties. Somehow the idea that a boundary layer in gelatinous water (jelly) might be interesting took root so I tested the idea.

    Mixed NaCl, TiO2 (titanium dioxide) and strawberry jelly together in a bid to make a solar cell/battery.

    Put the mixture in the fridge to set for a couple of days.

    No photochemistry evident at all which was perhaps predictable.

    So I put copper and aluminium electrodes on opposing sides of vessels containing the gel mixture.

    With an uncalibrated handheld multimeter, a potential difference appeared between the copper and aluminium electrodes (0.5 volts per cell). There was no linear relationship in terms of voltage increase in series, just slight increase in voltage (I used glass jars prone to Leyden capacitive effects...curiosity demanded fast answers over accuracy).

    But when I used plain old fashioned salt water instead of my fancy TiO2 NaCl gel mixture, I got 1.1v per cell in terms of potential difference between the copper and aluminium electrodes. In other words, the gel I made was less effective as an electrolyte than ordinary salt water.

    Photos attached.

    Attached Files:

    Last edited: Mar 31, 2013
  2. nLite


    Jan 27, 2013
    When you say that you used copper and aluminum electrodes with a salt water solution, it seems like the 1.1 V difference might be due to a redox reaction. You may want to try a control experiment with no light to confirm.
  3. alfa88


    Dec 1, 2010
    It sounds like a saltwater cell(battery) to me. Yeah, redox.
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    Damn, and I purchased all those strawberry jam batteries from China the other day. Don't go and tell me now that strawberry jam isn't a premium battery electrolyte!

  5. davenn

    davenn Moderator

    Sep 5, 2009
    alfa, buddy

    you are still about .... cool!!

    hadnt heard from you for a while and thought some one must have sacrificed you to Pele in the volcano to appease the god of fire ;)

    keep up the posts :)

  6. alfa88


    Dec 1, 2010
    It beats Aunt Bea's pickles.

    There's too many uber brainiacs beating me to the answers but I just got a pic programmer so I'll have plenty o' questions soon.
    I once contemplated a saltwater battery to power our condo but the cost of replacing the zinc anodes would be prohibitive as well as environmentally irresponsible. I once saw an experiment popping the top of a TO3 - 2N3055 where it produced a measurable current when exposed to light.
    Last edited: Apr 5, 2013
  7. quantumtangles


    Dec 19, 2012
    Yeah Redox

    I did not think for one moment that the salt water cell was a 'solar' cell.

    On the contrary, after the TiO2 NACl cell failed (in terms of photochemistry), I tested it in terms of it being a conventional chemical battery, using copper and aluminium electrodes.

    I got about half a volt per cell.

    In order to have a point of reference (a comparator), I used the same type of electrodes in a salt water solution. I got a higher voltage (about twice as high) using plain old salt water.

    This proved that my TiO2 NACl cells were useless in more ways than I had imagined. They were outperformed by ordinary seawater even in redox terms.

    If I gave the impression anything other than a redox reaction was going on in the saline comparator cell, I sincerely and contritely apologise. It was so obvious there was no photochemistry going on that I did not bother to test the saline cell in that regard.

    Ran out of time to try other combos, and made a mess in my kitchlab. Also had to get rid of the strawberry TIO2NACl jelly fast in case the dog ate it and I had to explain myself to a vet.

    And in terms of transistors, Alfa is right. There is a video on youtube where Rimstar powers a calculator using (I think) 2N3055 power transistors with the backs taken off and exposed to light (instead of conventional solar cells).

    I also found in earlier experiments (long after everyone else I suspect) that shining light at LED bulbs produces a potential difference. LED bulbs are mildly inefficient solar cells.
    Last edited: Apr 14, 2013
  8. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    Shining light at almost any semiconductor junction will produce a voltage.
  9. quantumtangles


    Dec 19, 2012
    Thanks Steve. I did not know that.

    If ignorance were a criminal offence I would be in ADX Florence.
  10. GonzoEngineer


    Dec 2, 2011
    Years ago, just for shits and giggles, me and a buddy made a camera with a UV erasable EEPROM. It worked pretty damn good, except the window caused a marked distortion to the image.:D
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