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Solar cells in parallel and series

  1. Dec 10, 2012 #1
    Hi,

    I am conducting an experiment whereby I have to measure the individual performance (on a per-cell basis) of solar cells on a solar panel. The panel has 20 cells, which are 4 strings in parallel of 5 cells in series each. The entire panel has a +V and chassis GND wire that I can open or close.

    I have the solar panel positioned in front of a high power LED to ensure that it gets roughly the same amount of light. (I am not looking for raw cell performance, but, rather, before/after tests).

    What is the best way to hook up a multimeter to an individual cell so I can figure out how much it has degraded? I am hitting these solar cells with things, and seeing how they perform after cracked.

    Do I need to sever the electrical connections between them so the results are not skewed?

    The attached picture shows what I am doing.

    I am not even sure what the best way of evaluating the health is. Should I be measuring with different resistances so I can get some kind of rudimentary IV curve? I do not know the intensity of the controlled light setup and I have no way of finding out what the intensity is, either. All I know is that it is the same. I am thinking that all I can do is get a good idea for how the voltage/current changes before/after damage.
     

    Attached Files:

  2. jcsd
  3. Dec 10, 2012 #2

    davenn

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    Gold Member

    Hi there :0

    getting at individual cells is pretty much impossible for most solar panels as the individual cells are buried in a sealing compund ... epoxy, polyeurathane etc and any attempt to get at the electrical connections of am individual cell is likely to damage it beyond usefullness

    Dave
     
  4. Dec 11, 2012 #3
    What I have is not like most solar panels. The cells are individually placed on a PCB in a way that the + and - leads are fully visible and accessible to a multimeter. This solar panel was manually constructed, and is of the form shown in the diagram. Assume that all the wires in the diagram are fully accessible to a multimeter.
     
  5. Dec 11, 2012 #4
    Your goal seems to be to test each cell individually before and after damage. If that's the case, and you can't somehow disassemble the panel into its individual cells, I think I'd cover up all but one string and work on one string at a time. Use an ampmeter, a voltmeter, and a potmeter to graph the IV curve. Make sure you include the short-circuit current and open-circuit voltage in your measurement range. Short out a cell with a wire once it's damaged, before moving on to the next. What color is your LED light source?
     
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