Solar panel backsheet scratch

[fabieville]

My 24v 250watt solar panel backsheet(tedlar) has some few scratches due to improper handling during installation. Will these superficial scratches cause any issues on the panel lifespan? will it allow moisture/water or debris to reach the cells?

I saw in a forum where someone was suggesting that you can use the electronic grade silicone to cover the scratches and that will do a perfect job of repairing the area, keeping out moisture,water and debris plus maintaining the full longevity of the panel.

Please give me your thoughts and ideas on this matter. I anxiously await your responses. I have uploaded a pic to let you see the scratches.

[DamonHD]

Hi,

I'd be concerned that the contact with the rear of the panel had caused mechanical stress and cracking in the silicon cells, weakening them in the face of thermal stresses or even reducing output right now.

Rgds

Damon

[fabieville]

Looking at the cells above the scratch area it looks fine. I dont see any cracks And when i do a short circuit test on the panel in full sunlight i am producing more than what the manufacturer stated. So does that suggest there isn't any damage to the cells or the encapsulated area and i am in the clear?

[DamonHD]

That may well be OK, or problems may show up later.  Don't confuse me with any sort of expert!

It is at least promising.

Rgds

Damon

[richhagen]

If the Tedlar is scratched through, then I think your concerns are well founded.  Any stress related issues caused by pressure on the cells you will be unable to do much about.  As for the scratch itself, I have seen older panels were damage appears to have spread from such a scratch or penetration.  I would be inclined to caulk over it or seal it in some way, specifically to keep moisture away from the EVA, which is more permeable to moisture as that could lead to corrosion in the leads or the cell backs.  As Damon pointed out for himself, though, I am no expert, just a bit of experience with old panels.  Rich

[OperaHouse]

If there actually is a puncture, I think tape would be a better option.  Something like kapton.  Most silicone calks produce acetic acid.

[clockmanFRA]

About 8 years ago, I was offered some Sharpe 190w PV panels that were seconds.

I chose and tested and got 17off.

While at the manufacturers/assemblers, they recommended that any repairs to the rear film or lead out box, as mostly all had some slight damage, that I use specifically only this stuff, and not just any ordinary silicone.

The panels have been excellent ever since, and the mastic stays and does the job.

Pics.
The special mastic.
Rear of the panels showing the scratches all covered, I couldn't get white colour.
I even re-sealed the front glass edge, it works well as we have a new eco system growing, haha.

 
   

[fabieville]

About 8 years ago, I was offered some Sharpe 190w PV panels that were seconds.

I chose and tested and got 17off.

While at the manufacturers/assemblers, they recommended that any repairs to the rear film or lead out box, as mostly all had some slight damage, that I use specifically only this stuff, and not just any ordinary silicone.

The panels have been excellent ever since, and the mastic stays and does the job.

Pics.
The special mastic.
Rear of the panels showing the scratches all covered, I couldn't get white colour.
I even re-sealed the front glass edge, it works well as we have a new eco system growing, haha.

 
 

In regards to the post above would the Clear Electronic Grade Silicone that I used works just as good as the silicone mention above? It contains good Dielectric Properties and it does not contain any acetic acid.

Do I have to clean the surface with pure IPA Isopropyl Alcohol 99.9% before applying the silicone?

[SparWeb]

Hi Fabieville,
I think patching it like you're doing is probably fine.  Yes, cleaning any surface before applying an adhesive is recommended, and your choice of IPA is a good one.
I can't be certain what the problem right now: is the scratch just in the Tedlar, or through the cell backing, or is it a scratch on the cell that you can see through the tedlar??  Exactly where is the flaw?  The picture looks like a pencil mark on the tedlar - hardly a matter for concern at all.

Anyway, I agree with Richhagen's opinion that a scratch on the cell isn't something you can do much about.  If there is a scratch on the cell then it's a discontinuity on the surface so thermal stress may reduce the life of the cell, but if it's clean under the tedlar and you patch it well then you've done everything you can to preserve it.

A scratch in the tedlar just needs a patch to fix like you're doing.  Questions about stress if the tedlar is ripped are a bit overblown since the tedlar is hardly going to apply any stress to the cell that the cell won't feel already due to heat and pressure etc.

[fabieville]

looking at the panel i cant tell if the scratch has reach as far as the cell backing. If it is a case where it has reach as far as the cell backing by passing through the encapsulated(eva) backing but didn't get to go through or scrape the cell backing then would the silicone patch be enough to fix the problem and maintain the full lifespan of the panel?

[SparWeb]

If it hasn't even scratched through the tedlar then the repair you are doing now is all you need.

[fabieville]

didn't really quite understand the last post. Did u mean if it has scratch through the eva or the tedlar then the repair is all that is needed?

And can someone please tell me if the repair will still maintain the full lifespan for the panel?