Solar Panel fault?

fwor

We've not had much luck with solar panels over the years. This is a single monocrystaline 150W panel mounted on a camper van roof, and it seems to have failed (if so, it will be the second one to do so).

The reason I'm asking here as a question, is that the voltage and current output readings I'm getting are odd. The first one failed completely dead - near enough no output.

But this is unlike any failure that I've seen before. Open circuit in full sunshine is 22.6V (IIRC that's almost the full original spec) but the short-circuit current in full sunshine is 0.01A. I can't think how it can have failed in a way that results in those figures!

So - can anyone confirm that this is in fact a known failure mode for this type of panel, and it is just fit for the bin?

QrizB

I'd guess it's a high resistance failure in the panel. You'll get the right open circuit voltage but as soon as you apply a load the supply will collapse.

What make and model of panel? Is it one of those semi-flexible ones or a rigid framed one? Any manufacturer's warranty worthy of the name?

fwor

I *think* it's EcoWorthy, semi-flexible. Understood - the semi-flexible ones generally prove to be a lot less reliable than the rigid frames ones, but we don't want the extra 40mm of height of a rigid, as the van will just about go under most height restriction bars.

The warranty is probably a lost cause. It was stuck down with VHB tape and so the chances of getting it off in one piece are not great! And the Ebay shop that sold it to us no longer exists (though strictly that isn't relevant to a warranty claim).

QrizB

I can sympathise with the desire to stay low-profile and get into car parks! Sadly that means you're stuck with skinny panels, which generally means the semi-flexible ones.

Back in the day BP made a range of aluminium-backed panels which were more robust. I had one on a boat and it worked well. Sadly I think they stopped producing those 15-20 years ago.

fwor

Yes - I have an aluminium-back-sheet panel (not by BP though) on another camper van and that is still working after 8 years. Though the output is slowly declining and will need replacing fairly soon.

I wonder if the CIGS ultra-flexible ones are any more durable? But they are several times the price of the semi-flexis, so it's a bit of a gamble!

QrizB

CIGS panels are supposedly really rugged, but the scary prices always put me off.

I guess the only bright side is that panels in general keep getting cheaper. I see you can pick up a 150W panel for about £50 now.

fwor

Yes - we are going slightly more expensive to get an ETFE outer layer (because the first one we had did not and it went nice and milky within one year!) Should still be under £80 though (100W panel). 

We will also swap out the existing PWM controller for an MPPT to make up for the fact that it's a 100W panel instead of 150W. It won't compensate fully, but it will go some way towards it.

QrizB

I was thinking of mentioning about controllers, but didn't want to complicate things! Monocrystalline panels have a higher Vmp and lower Imp compared to polycrystalline, so a poly panel is a better match to a PWM controller. If you're changing to MPPT then you'll see the advantages of a mono panel.

Good luck with whatever you choose.