Mixing Solar Panels Sizes

Discussion in 'Solar Power' started by Vennwood, Apr 2, 2009.

  1. Vennwood

    Vennwood Read Only Funster

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    Hi All,

    I'm trying to discover if there is any issues with having different size solar panels within the same circuit - does anyone have any answers?

    I'm wanting to add a 120W and possibly a 80W panel to my two 130W kyoceras. Finally does anyone have the diffinative answer for the size of regulator that would be needed for say total panels of 425W with a 25Amps regulator?

    Pete
     
    Last edited: Apr 2, 2009
  2. pappajohn

    pappajohn Funster Life Member

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    hi pete,

    your questions a bit confusing as you answered your own question....25amp minimum.

    watts divided by volts equals amps

    425w / 17v (panel output) = 25amps.

    cant see any reason not to mix panels providing the voltage for each is the same all the amps will be used.
    a bit like filling a bucket using 4 taps.
     
  3. 656

    656 Read Only Funster

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    I have a 60 watt and an 85 watt one, both in the same circuit with no problems.
     
  4. scotjimland

    scotjimland Funster Life Member

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    You can mix and match any size panels.. with the proviso that John stated.. :thumb:
     
  5. Vennwood

    Vennwood Read Only Funster

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    Thanks guys,

    It's just that I have been told by a supplier that mixing isn't possible AND that, and I quote

    "When we perform system design we us the "Photovoltaics in Buildings - Guide to the Installation of PV Systems", 2nd edition. This is used by the industry until a British Standard is available. This standard requires that all dc components (including charge controllers) must be rated at Isc x 1.25. This is due to the fact that Isc are given at standard test conditions (stc). However in the field conditions can vary considerably from stc, and so the multiplication factor of 1.25 is used to allow for maximum values that may be experienced. In your case with 3 panels this would be 24.06 x 1.25 = 30.075A"

    I've tried contacting Kyocera but no joy.

    EDIT: Sorry forgot to say - I have a SunSaver Duo regulator rated at 425W and 25 Amps
     
    Last edited: Apr 2, 2009
  6. scotjimland

    scotjimland Funster Life Member

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    Hi
    It's normal electrical practice when designing a system to specify control equipment rated at more than the max load, so their guidance on charge controllers makes sense.. but as you already have a 25A unit I would fit it and see how it performs.
     
  7. Vennwood

    Vennwood Read Only Funster

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    Thanks again,

    Just heard back from Morningstar tech support and they confirm that its ok to add panels up to the rated output of the Duo without problems so that's what I'll do.

    Pete
     
  8. Vennwood

    Vennwood Read Only Funster

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    Hi All again,

    Just an update on this thread as I have heard back from Kyocera and they say in relation to mixing panels

    - "then the either the voltage or the current the of that
    circuit will be limited to the "weakest" modules values.
    For sure this will work. However, you will face energy losses compared to the
    optimal solution."


    So they advise you NOT to mix panels but use same size......

    Pete
     
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