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Question: Connecting multiple panels

Discussion in 'Photovoltaics' started by Hans Kroeger, Sep 28, 2003.

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  1. Hans Kroeger

    Hans Kroeger Guest


    is it correct to say that 2 of the same type of panels can be connected
    in parallel to a single charge regulator.
    If true, is it also correct to say that half of the total power is
    available if one of the 2 panels is shaded, whereas the other one is

    Thanks for the help !

    Kind Regards
  2. Hans Kroeger

    Hans Kroeger Guest

    Hi Duane,

    thanks so much for the explanations!
    Is this what some manufacturers call "blocking" diodes?
    I thought that normally these blocking diodes are already included in
    the panel.
    If they are, can I assume two unconditional YES to my original

    Kind Regards, Hans
  3. Hans Kroeger

    Hans Kroeger Guest


    many thanks again....BTW I like your homepage!


  4. If you are referencing 12-volt systems, then you can parallel the modules
    (some manufacturers recommend series fuses) as the battery state of
    charge and charge rate will establish the operating voltage.

    In the 12-volt case, shading a module (or even only a few cells) will
    effectively stop the output of the shaded module. The other module
    will continue to function.

    There are both Bypass and Blocking diodes associated with
    PV module wiring. I suggest visiting a major PV manufacturer's
    web site and downloading a module user manual. Shell has a
    good one for the SP75 series. This will explain the diodes.

    Above 12 volts the bypass diodes and either blocking diodes or
    fuses are required to avoid hot spot damage if a cell is shaded.
    The bypass diodes limit the reverse voltage that can cause a cell
    to heat up and perhaps burn due to shading. All first class modules
    that meet UL, EU, or IEC standards must have installation instructions
    that detail the required diodes. Many manufacturers include the
    bypass diodes within the junction box. Few include blocking diodes,
    but some have a place to install them in the junction box.


    Bill Kaszeta
    Photovoltaic Resources Int'l
    Tempe Arizona USA
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