Moisture in rigid solar panels

[Steve928]

I've had 3 mono rigid/framed solar panels, all appearing to be good quality and from the same German supplier, that have suffered from water ingress around the periphery adjacent to the frame. The moisture lies between the backsheet and the EVA encapsulant (so below the cells) and in 2 of the panels has not affected output. The 3rd. panel, however,  had dropped in output significantly and as it was in series ended up reducing the output of the entire system. Interestingly after only a day standing on end with a small slit in the backsheet to allow the moisture out it has returned to full output.

Now clearly framed panels lying flat on a motorhome roof tend to sit with a pool of water against the 1-2mm upstand created by the frame and in winter are rarely dry. Presumably they should be able to cope with this though without any special precautions? Has anyone else suffered the same problem and put in place any preventative measures e.g. silicone sealing around the frame edge, cutting a drain slot in the frame etc. or have I just been unlucky with this supplier?

I've put new panels up today and it's great to see the system performing well again with the batteries fully charged and the AES light on even in low February sunlight. I'd prefer these new panels not to go the same way though..

[Globebuster1]

I don't think it's a bad idea to try and future-proof the new panels Steve.

When I fitted mine last year I 'gunned' in all around where the panel meets the frame.

I used clear CT1, as it's a PU based product so shouldn't affect the anodised aluminium.

I personally would avoid using silicone.

I did think about a couple of limber holes in the frame, but decided against that.

[Steve928]

Yes I think I'll run some sealant around the frame, it can't do any harm. I only mentioned silicone because I know that's the only clear sealant I have in my armoury, but I'll use my favourite Soudal RV61 and try and be neat.
The original, damp frames do have limber holes in the base of the double-wall section of the frame while the new ones (from low-energie-supermarket) don't, but I've added them in the end frame sections which have been drilled for the securing screws.

I'll see how it goes; hopefully there'll be a remote chance of some comeback under warranty if these go the same way.