Parallel panels and shade

shift
shift Solar Expert Posts: 48 ✭
in Solar Beginners Corner #1
If you wire 2 panels in parallel connected to a charge controller(with a diode) and one panel is in sun/one shaded. Will there be any negative effect? or is it worth installing a separate diode on each panel?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,642 admin
    #2
    Re: Parallel panels and shade

    I would not install a blocking diode... The solar panels are usually spec'ed to their Voc rating for "back voltage"... And even in shade, the panels still develop most of their forward voltage--they just are not capable of providing any forward current until the shaded panels are back in full/equal sun.

    The blocking diodes were primarly present to stop batteries from discharging to direct attached panels at night (discharging current). Even then, diodes were not really even needed for 12 volt battery banks, break even for 12 volt, and could save energy for 48 volt batteries.

    But since pretty much everyone uses charge controllers these days--Charge controllers block reverse current flow so blocking diodes are not needed anyway to save power at night.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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