Solar Panel Spec Question

Discussion in 'General Electronics Chat' started by ErnieM, Sep 8, 2012.

  1. ErnieM

    Thread Starter AAC Fanatic!

    Apr 24, 2011
    I am currently reviewing an existing solar power system for the Huntington Lighthouse. Our system is powered by three Solar module SM46 panels. installed as "spares" by the USCG during their last rework of the power for the light itself. The light is still an official and active aid to navigation.

    My issue is the current output of these panels. They are rated for 46 watts or 3.15 amps at 14.6 volts. However, the Voltage-current characteristic curve (at same irradiance) indicates a current of half this value.

    Does anyone know why this discrepancy exists? Is there some other factor I am unaware of?

    • V-I.GIF
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  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
    Post the whole spec document. I'm seeing footnote (5) which likely holds the key to the explanation, but without the verbage, I don't understand it...

    ps. I see that you did post the link to data sheet. I'm guessing that Siemens screwed up and included the wrong diagram...
    If I was buying a new one, I'd be calling their customer service dept.
    Last edited: Sep 8, 2012
  3. ErnieM

    Thread Starter AAC Fanatic!

    Apr 24, 2011
    You caught the link but the footnote 5 is in the image anyway.

    This is an existing installation, and I agree: looks like the incorrect figure was pasted into the document.

    Thanks for stopping by. :D
  4. #12


    Nov 30, 2010
    I'm with MikeML. Phone Customer Service.
  5. ErnieM

    Thread Starter AAC Fanatic!

    Apr 24, 2011
    If one follows the link in the SM46 document you discover a "spoof" sight and not the Siemens Solar sight. Hitting Siemens directly yields no hits on the SM46 panel, nor for "solar module" in general.

    It seems Solar Siemens is out of the solar panel game. Some of their units may be out there in distribution chains which is why I do find some data sheets out there. This is the first time I researched a solar panel; looking at several other units I discovered no apparent contradictions. The end points of the V-I characteristic matched the ratings of the electrical characteristics.

    All I really need to evaluate what we have is the numbers off the electrical characteristics table, so I will call this done and good.

    This is an existing installation so I don't see any need to bug someone for some data about a product they no longer make. Only if I was going to purchase something new would I give em a call.

    Thanks for letting me pick your brains. :p