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Mixing PV panels

Discussion in 'Photovoltaics' started by Starbase, Apr 9, 2004.

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  1. Starbase

    Starbase Guest

    Hi group,

    I currently have one large 64 watt amorphous panel from United Solar Systems
    Corp (model US-64) which is proving a little under powered for my current
    use, especially in the winter months.

    As my budget is limited I have purchased a second 80 watt BP Solar BP380U
    off e-bay. My question is;

    Is it possible to add panels of different types connected in PARALLEL (if
    not an explination would be appreciated, maybe it will have something to do
    with voltage differences ??) or should I run the two panels seperately. My
    current charge controller will handle both panels comfortably so this is my
    prefered method of use, otherwise I feel a small electronics project


    Chris Newman
  2. Luc Collin

    Luc Collin Guest


    The two modules/technologies have different electrical characteristic.
    Specifically, they have different sensitivity to light and different maximum
    power point. So if you do hook them in parallel, two things may happen

    1- both will underperform because neither will operate in MPP.
    2- back feeding into another panel because they operated differently at
    different light intensity.

    I would either isolate them using a diode, or if you are charging a battery
    I would use a seperate controller. Getting a sunguard is probably if few
    buck more expensive but it will be easier to install and probably more

  3. For 12-volt systems you can simply hook the modules in parallel
    as the battery state of charge determines the operating voltage
    and current. The UL listing of the modules may require fuses
    in series with each module, check the instructions that UL
    requires be furnished with each module.

    Bill Kaszeta
    Photovoltaic Resources Int'l
    Tempe Arizona USA
  4. Starbase

    Starbase Guest

    Thanks for your replies chaps, the second panel has arrived and I have
    decided to rig them up to the same charge controller for the present time
    pending experimenting with some circuits I have seen on the internet (I also
    have a 15 watt solar panel with a blocking diode so I am just going to
    connect that straight accross the 200 Ah battery bank, thus bypassing the
    charge controller as I am always drawing about 10 watts from the system
    anyway, so I reckon that will be more efficient).

    Welcome to the Collective

    The future is Borg
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