Solar panel problem

Thanks Allan, I thought these things were pretty bullet proof, cheers.

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.

The panel was disconnected from the regulator, I don't remember seeing any thing across the wires, will check though. Thanks.

Does it have a plastic terminal box mounted to the panel, if so then
open the box and check the voltage on the flat strips coming from the panel.

The diode is normally mounted in the terminal box if it has a normal panel setup though in this application there may not be either the box or diode.

There was a small plastic box where I tested the flat strips, cheers.

Then it would appear it's a bin job.

Before the reg, no battery, it was straight off the panel, cheers.