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Blocking diode getting hot

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  • Sunking
    You diode current rating is too low is my guess. It makes it to physically small to dissipate the amount heat generated. It is also guaranteed to fail from excess current. Easy fix get one sized appropriately.

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  • inetdog
    Originally posted by J4mie82 View Post

    I was wondering if anyone could help me with a problem as I am new to solar panels.
    I have installed a 80w solar panel to a boat with a marlec wind/solar regulator. The details from marlec stated a blocking diode was needed. I installed one to the positive side of the solar panel ( p600d rectifier) that should be capable of doing the job. My question is should the diode be getting extremely hot. Too hot touch when there is full sunlight. The wires have not started to melt yet but I am getting concerned. I have seen diodes with heat sinks but sure for a 80w panel this would be over kill. Have I done something wrong or is this normal with diodes?

    Any help would be great,


    The diode is too small for the amount of current you are putting through it.
    It should be a low voltage (Schottky) diode. If it is a standard rectifier diode it will have a forward drop under load of about 1V. If your panel puts out 6A then it will dissipate ~7 watts and will for sure need a heat sink.
    Get a better diode and maybe a heat sink for it.
    A modern PV/RE type charge controller will have the diode function built in.

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