Series/parallel problem?

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engage
engage Registered Users Posts: 5 ✭
in Solar Beginners Corner #1
I am having trouble diagnosing my CIS solar panel (see attached for a picture of how I wired it - I appologize in advance for the ghetto way of attaching it as I suck at picture editing). I wired three cells in series and the rest in parallel.

Each cell produces roughly 5.5 volts and 35mA. The total voltage I get in full sun is 16.6VDC, which is good, but my amps is only 122mA. It is as if only 1 line of cells is working right. By my calculation I should be getting around 600mA or more and I have no idea why my amps are so low. I checked each cell and they produce around 35mA each.

I am hoping the problem is simple as this is my first attempt at wiring a cell. Please help!
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #2
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    Re: Series/parallel problem?

    there's your problem if you actually wired it as you have shown. a series string is always + to - or end to end like flashlight batteries are. what you have shown is that 1 cell of each string has been reversed. this counteracts the general flow and it can damage that reversed cell.
    i am confused how you measured 16+v when you don't have enough cells in series to achieve that as each cell is usually in the neighborhood of about .55v and not 5.5v. for most 12v pvs there is usually 36 cells all going + to minus in series. you have 5 strings of 6 cells with a cell reversed in each string. if all were in series at .55v each this gives a voc of 16.5v so are you sure the diagram is correct in how it was wired?
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  • engage
    engage Registered Users Posts: 5 ✭
    #3
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    Re: Series/parallel problem?

    I achieve 16.6 volts because they are CIS cells and not a typical silicon cell. Each cell produces around 5.5volts. I'm not an expert or even close but I read they are more-or-less mini panels so they hit higher volts for each cell.

    Thanks for your response. I guess I will have to go back to the drawning board on how to wire a 5 row 6 column panel with 3 or 4 in series (to hit between 16-22 volts) and the rest in parallel to up the amps.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #4
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    Re: Series/parallel problem?

    ok, assuming the 5.5v each cell then is it your goal to have 33v output open circuit? 6 x 5.5v = 33v. if it is desired then disregard the rest.
    33v would be high for 12v operations as 4 of those cells in series would yield good open circuit voltage for 12v operations. 4 x 5.5v = 22voc. you would not be able to utilize all 30 cells as it would be 4 cells x 7strings = 28 cells used. at the specs you have listed this would give 7 strings x 35ma = 245ma.
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  • engage
    engage Registered Users Posts: 5 ✭
    #5
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    Re: Series/parallel problem?

    I would like to have at least three (maybe four) in series to get adaquate voltage for a 12volt system. The rest would be in parallel to up the amps. I would have to do it with 5 rows of 6 cells. How could I wire it to get those specifications?
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #6
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    Re: Series/parallel problem?

    it won't be easy, but you do have to rewire the last 2 righthand cells of each row anyway so you automatically have 5 rows of 4 after the last 2 cells of each are disconnected. once those end cells are removed you can then place them so as to have it as a 2 above 2 arrangement and 2 of these can be done in the same space that you have leaving 2 out all together. rewiring all of those strings can be problematic depending on your mounting arrangement. if the present arrangement is permanent without the possibility of removing them, then possibly the best that you could do is tap between the 4th and 5th cells to parallel the strings from that polarity and this would omit 10 cells. if none of these are possible then you have 30 junk cells in a junk module as it is presently not usable as it is.
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  • GreenPowerManiac
    GreenPowerManiac Solar Expert Posts: 453 ✭✭✭
    #7
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    Re: Series/parallel problem?

    Engage,

    Your setup looks like about 4-8 volts per string(in series) then a total of 4 more rows, all in parallel. The voltage you're receiving is about right at 5.5v. You're missing about 6 more cells and some different wiring.

    My solar panels have 36 cells in series starting with the negative tab wires and end with the two positives giving about 19-20v in bright sunlight no load. I'll show an example. If you wish to achieve a 12volt system, then each panel(the cells) are wired in series and "panel to panel" are parallel to stack the amps and maintain a constant voltage.
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  • engage
    engage Registered Users Posts: 5 ✭
    #8
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    Re: Series/parallel problem?

    I went back to the drawing board and I think I came up with a way to get 4 in series and parallel them all together (I added a sixth row of cells). Would you guys mind looking over my diagram and tell me if I got this one right before embarking on a soldering spree? Thanks!
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #9
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    Re: Series/parallel problem?

    4 cells in series, and 9 strings in parallel ? Should work, if all cells are same size.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #10
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    Re: Series/parallel problem?

    looks ok to me too and was basically what i had in mind in the drawing except that you added 2 more cells to complete another string.
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