Tuesday, Nov 22, 2016 at 10:21
Wayne, electronic devices are innately fragile. They can fail for no discernible reason. In the case of
Solar Panels, they are constructed of a number of PV cells connected in series, in your case probably 30 to 36 cells. Being in series, if one cell fails and goes open-circuit, then the whole series chain is open-circuit and no current can be produced. Sometimes the array is composed of groups of cells each with a 'bypass diode' to allow (diminished) current to pass a non-performing cell group, but this is probably unlikely in your
panel. Also sometimes a diode is positioned at the
panel output to prevent current 'back-flow' at night time. This diode is in series with the output not "across" as has been suggested. In any case, if the
panel has been furnished with a regulator, this diode is usually omitted as you have indicated.
If access were available to the rear of your cells then it may be possible to
test each cell and isolate a faulty one but typical construction of an array usually precludes access and repair. It is a virtual 'sealed unit'.
By disconnecting the battery and regulator then testing directly across the
panel output as you have done, you have isolated the fault to be within the
panel.
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