Scratches on PV Panels

[Reddy]

Hi,

Just had 16 PV panels fitted last week and all seemed to go well, but have just noticed a few of the panels have quite long scratches (see images) on the top of them (scaffolding is still up, so I went up for a look)! I can really only see the bottom row of panels and 3 out of these 8 are scratched. Is this likely to effect the efficiency of the panels and do you think its reasonable to expect the company to replace them?



thanks in advance for any help.

David

 

[whinmoor]

It's not ideal. Imagine if you spent £10k on a new car and it turned up like this. It might drive ok but would you be a happy bunny? I'd be withholding final payment until sorted although with the FiT rush, you may find your hands are tied. Better to act now otherwise the scaffolding will disappear and cost/hassle will increase.

 

[Reddy]

Thanks for replying. Unfortunately, the final payment was made last week after installation so I could get the MCS Cert and get everything sent off for the FIT application. I only went up to have a look today out of curiosity and that's when I noticed the scratches. I will get in touch with the company and see what they have to say.

Does anyone know if this will any effect on power output?

 

[whinmoor]

Power output initially wouldn't be much affected but I expect the scratched panel will degrade quicker and the anti-reflective coating may well be compromised. Are the scratches definitely on the outside of the glass? Can you feel them when you run your fingernail across them?

 

[Reddy]

Hi, the scratches are on the outside of the glass.

 

[and]

I had the same: 10 out of 16 panels scratched on my install 3 Nov.

Installer replaced one panel that had a 'stone chip' in it, wasn't keen to replace any of the scratched panels though.

It's difficult to know what to do ... I got a cheap install (10K) and that was the week all the panic had kicked off - lucky to get an install at all, lucky to get REC 245 panels and Power One 3600 ... I do remain unhappy about the scratches though.

The scratches were (I'm 99.9% sure) caused by installers stacking them flat up on the scaffolding with just one person handling them and effectively dragging the aluminium frame of one panel across the glass of the one below ... I thought at the time it was a crap way to be dealing with the panels.

Now all the panic is over, perhaps I ought to chase up the installer ... I was being perhaps a bit too kind to him, knowing that they were working under a lot of pressure trying to get materials and installs fitted in before the deadline.

I'll pop up on the roof on a dry day and see if the scraches have weathered away at all.

 

[Guest123]

Would you be happy taking delivery of any other item of 'brand new' equipment with dirty great scratches on it......I certainly wouldn't.

 

[moggy1968]

it will compromise the performance of the panels and now the coating has been compromised water and frost will get in, causing it to lift even more. degredation of the panels will be significantly accelerated.
In ten years time the condition and performance of your panels will be significantly less than you would expect (maybe sooner)
it just isn't acceptable.

 

[solarcat]

I really do not agree that the scratches can in any way affect the panel's durability. All MCS accredited panels are encapsulated in very thick glass and a scratch isn't going to make water go anywhere near the PV cells.

What may happen however is that the scratches may cause some very slight shading onto some cells, and even if only a couple of cells experience some shading the output loss may not be insignificant as cells are connected in series and so are the panels..,

I would suggest you ask for a replacement. If the modules were already scratched when the installer received them, the module warranty should cover that.

 

[moggy1968]

does shading afect the performance of a panel, yes, do scratches inpair the performance of a panel, yes, in exactly the same way. It's not to do with the cells, it's to do with the transmittence of light. Solar panels (good ones anyway!)have hydrophobic and antireflection coatings on them to improve the transmittence of light (by about 8%) and the panels ability to self clean. If you damage this coating water can get underneith. this then causes lifting of the rest of the coating, causing a delaminating effect over the surface of the panel. This forms crazing of the coating which will block the light transmittence and will become more and more extensive as more time passes. The effect accelerates with time as the affected surface area gets larger. superficial scratches that don't penetrate the coating you'll get away with, but deeper ones are a problem. by deep bear in mind the coating is nanometers thick (thats 1.0x10 to the power of minus 9)
but then what do I know, I've only got a degree in optics!

 

[moggy1968]

coincidently my mate rang me just after I posted so I asked him. He confirmed the above.
He's a doctor of physics specialising in thin films technology, probably one of the top 3 specialists in his field in the world so I think I'll take notice of what he says!

 

[and]

Thanks moggy1968 for the info concerning scatches. I've just written to my installer now the busy period is over to see what he advises.

Reddy - can you keep posting to let me know how you are getting on with dealing with the scratches on your panels.

I include a photo of one of my nine scratched panels

 

[moggy1968]

eek, thats bad!!

 

[Reddy]

thanks moggy for the information. I have emailed the company today and will keep you informed as to the outcome.

 

[and]

Sent the following email (and photo of a scratched panel) to REC headquarters in Norway yesterday (no UK office):


“Please could you advise me on whether an 'alloy scratch' on my solar panel (caused by the aluminium frame of one panel being slid over the glass of another panel) will have any of the following adverse effects:

- void the 25 year output warranty
- damage the integrity of the anti-reflective coating
- be likely to cause the panel to degrade/lose output quicker than an unscratched panel

Please could you also confirm that indeed the anti-reflective coating is on the exposed side of the glass.”


A reply came back today:


“Dear Sir,

Thanks for contacting us.
No, this small scratch will not affect your product warranty.
Moreover, we find it very unlikely that this scratch will cause the module to degrade over time.
So nothing to worry about.

Regards,
Christian Heinlein”
Christian Heinlein Ph.D. | Senior Product Manager | REC Solar AS
Mobile: +47 928 28 546| Fax: +47 67 57 44 99
www.recgroup.com

 

[moggy1968]

ok, well that sounds reassuring!
still, given the example above I wouldn't want a new car with a scratch on it!

 

[yorkshiremike]

Are they actually scratches? It depends what the anti-reflection coat is (some are quite hard), but glass is a lot harder than aluminium and you can't usually scratch it with aluminium. However, you can 'draw' on glass with aluminium and leave a thin layer of aluminium on the glass. It's a common problem where aluminium pots and pans are used on glass hobs. Usually solution is to leave some dilute bleach on the mark for a hour or so (which corrodes the aluminium) then rub off - not sure I'd do this on a panel though unless knew that the bleach wouldn't attack the AR coat and it would need keeping off the aluminium panel frame.

 

[moggy1968]

it will attack the AR coat. best bet might be spectacle cleaner!!
It is possible to scratch the coating not the glass. the coatings aren't as hard as the glass.

 

[deeyup]

Try methylated spirit

 

[and]

Certainly on my panels the 'scratches' are indeed a thin layer of aluminium.

The installer wanted to clean these off using a stanley blade but I pointed out on a downloaded REC maintenance sheet that such things were on the DO NOT list.

If the scratches are as the Norwegien REC man says, not likely to degrade the integrity of the panel, then perhpas they are best left.

It is indeed like having a scratch on a new car, it shouldn't be there.

 

[moggy1968]

yep, we use meths in the optical industry for cleaning coated lenses so that should be ok, just don't use it on ploycarbonate!!

 

[SolarCity]

If I were you, I'd date and keep a copy of that email they sent. If there ever is an issue, it'll give you some leverage.

 

[Reddy]

Hi All, Just an update. Top marks to the installation company, they have agreed to replace the scratched panels

 

[Worcester]

@moggy, I read your comments and whilst we all now about the efects of shading - do you have some evidence with regards to your claims of long term detriminetal effect - e.g. case studies, published papers etc that I could read?

And yes I've talked to my brother who actively works in the field that you qualified in and abandoned

 

[moggy1968]

The effect I have seen are specifically on optical lenses where you see a pattern of delamination along the dges of a scratch on an AR coat. you don't see it that often because by and large spectacle lenses are replaced every couple of years or so but I have seen it on older lenses and those with inferior coatings from companies that suggest you should have gone to, but I think maybe you shouldn't!
Clearly any marking on an optical surface will affect the transmission of light through that surface, be it dirt, scratches, or shade (although not strictly a marking on the surface.

 

[and]

Reddy - Very good news that you are getting your scratched panels replaced ... I haven't yet heard back from my installer since I emailed him a couple of days ago, but you getting your scratched panels replaced at least sets a precedent.

I think logic dictates that what moggy1968 points out about degredation of AR surfaces is correct, and it concerns me that fifteen years down the line these scratches might indeed have caused degredation.

It is an expensive and long-term investment that ought to be installed scratch free.

 

[Reddy]

Very pleased - the installation company replaced the 3 scratched panels yesterday, no questions asked. They asked me to check the new panels after they had done and they all looked fine.

and - hope you get your panels sorted. The fact my installer replaced my scratched panels without argument suggests that it was the 'right' thing to do and they were aware that scratched panels could suffer problems in the future.

 

[fiardor]

Very pleased - the installation company replaced the 3 scratched panels yesterday, no questions asked. They asked me to check the new panels after they had done and they all looked fine.

and - hope you get your panels sorted. The fact my installer replaced my scratched panels without argument suggests that it was the 'right' thing to do and they were aware that scratched panels could suffer problems in the future.

That company wouldnt be Eco-Fusion by any chance?

 

[Reddy]

Hi fiardor, no the company is not called Eco-Fusion.

 

[and]

Have had the worst one of my nine 'scratched' panels replaced, which I'm happy with.

I'll keep my eye on any degredation around the 'scratches' on the panels to see if it affects the AR coating.

It's difficult to say, but up on the roof it looked like the 'scratches' (caused by aluminium frame of one panel coming into contact witht the glass of another) may be being weathered away.

It was reassuring that REC said such scratches do not affect the 25 year warranty and that they think it unlikely that the AR coating will have been affected.

All in all, I'm just happy to have a nice system on the full FiT rate that I now feel happy about. Am looking forward to sunnier days, though am impressed that it's clocked up nearly 100kW in December!

 

[Reddy]

Good news and!

Wow 100kW in December, mine have only managed to clock up 7kW in about the last 2 weeks (4kW system, SW facing, Manchester)! Does this seem right?

 

[and]

Well, I believe I'm heading for 100kW by the end of December to be more accurate, from 1 Dec to yesterday, it is exactly 86kW.

Sunday 18 Dec, the sun was out = 8.8kW, yesterday it was grey and rainy = 0.5kW.

At the end of the day, it just depends on if the sun is out or not.

As you can see from the above, on a grey winters day, the output is negligable.

I chart my output on:

REC3.92kW 3.920kW

I also look at others outputs in various parts of the UK with similar sized arrays (3.92kW) ... which will be more interesting and relevant come spring and summer when it will be useful to know that my array is generating what it should be by comparing it to others.