Solar panel output questions

[Oscarpop]

We installed 2 flexible solbian panels to our bimini in march last year. They are meant to produce 5.25 amps each and generally have been doing so.

However I am not sure that they are still working as efficiently.

Yesterday in full sun at 1 pm they were only putting out 5 amps between them. One was producing 1.5 and the other 3.5

Now I had a 2am start yesterday, and when I'm tired I tend to worry unduly that everything on the boat has broken.
However can I assume that at the end of August, the sun will be too low in the sky to allow the panels to produce more than 50% of their previous output?
Secondly . If a panel fails does it normally fail totally, or does the output wane ?

I have examined both panels and they are unmarked. There is no sign of de lamination or any wear on the unit/wires/ junction box

 

[noelex]

Compare the output of the two panels in near identical conditions. Check there are no shadows on one panel and the output should be closely matched.

 

[charles_reed]

Flexible (or semi-flexible) panels do have a lower output and shorter working life than glass ones. However, a shadow across the one panel could easily account for the difference in output.

A 50% efficiency is, in my experience, unless the panel is adjustable to maximise insolation, a pretty good output especially in the UK.

 

[john_morris_uk]

Surely the state of the batteries will affect things as well. If the batteries are completely full, perhaps the amps mentioned were all that they would accept?

 

[pcatterall]

Surely the state of the batteries will affect things as well. If the batteries are completely full, perhaps the amps mentioned were all that they would accept?

Yes that is a valid point but why is one producing more than the other? It must be position in respect of sun or shade ( just a rope or pole) affecting one or one panel for some reason is failing( but only 2 seasons old) or connections or...... what have I forgotten??

 

[heard28]

Are the two panels directly in parallel? I could imagine that if there is a slight difference in output voltage, then one would naturally provide more current than the other in that situation, especially if the batteries were reasonably near full. You could isolate each panel in turn, and compare output without the other panel interfering, maybe? However, I know that my own (smaller) panel drops output very quickly with only a small shadow across it - even the shade of a shroud seems to make a noticeable difference.