Cell Discolouration

[whinmoor]

We fitted some black Upsolar poly panels last week. Our customer has noticed that one cell on one panel is a different colour.

His suggestion is: " It looks as if there is liquid in the panel or the silicon is not of the correct consistency."

I can't believe that there is liquid in the panel but has anyone got a convincing explanation for this? The performance appears to be unaffected but it's difficult to tell as the system is very new.

Has anyone else come across this?

 

[Gavin A]

trick of the light, though it looks a little like the panel maybe a little distorted, as if the bottom corner has been pulled down a bit by the clip / the rails aren't entirely flat.

Poly cells themselves aren't exactly renowned for being uniform in colour either.

 

[whinmoor]

I asked the same question to the supplier who said:

"This discolouration is normal, it will not affect the performance. It is not water, and it will be fine. It is just a natural variation in the crystals of the silicon."

 

[SpitfireW'sale]

To be fair it is not uncommon to have slightly different colour across cells and modules in an array - this would not be viewed as an issue other than with aesthetics. The unusual thing with this example is that is appears to be a line across the module itself rather than different colour cells? Either way, unless you can prove the module is underperforming then the chances of Upsolar replacing it are practically nil so unless you want to foot the bill yourself the customer will have to live with it. Gavin A's explanation sounds plausible - it would only need to be a small amount that the panel was pulled off square to change the colour reflected from the cells.

 

[whinmoor]

It turns out the customer isn't referring so much to the darker cell. He has noticed a diagonal line running across the panel which I hadn't grasped from his description. Spitfire did pick up on this though. This wasn't apparent from the photos I took when we had finished the installation - although I obviously wasn't focussing on this aspect when snapping our handiwork.

 

[Gavin A]

that was what I was referring to as well, it looks a bit like a stress line in the glass as if the panel is bent slightly, which could be the bottom left corner being even a few mill lower than the rest when clipped in.

 

[SolarCity]

Good God, you fellas have got good eyes. Even after having it pointed out to me I can barely see it.

 

[whinmoor]

I went up on the roof to view this installation this morning. The discolouration was not visible from either the ground or roof. I was pretty pleased with the workmanship actually. The cables were tied up nicely and everything looked ok. I’d have preferred a couple of inches off the rails but apart from that minor gripe, I was happy.

The customer and I looked at the photos on his PC and came to the conclusion that there was nothing to see. It’s on Solar Edge so the shading impact should be limited and the generation meter is clocking up nicely. I only wanted to put four panels to keep farther away from the dormer but he insisted on five.

When I was packing up my stuff, his dog bit me! It was only a nip which didn't draw blood but gave me quite a handy negotiating platform. I'm not planning to sue!

 

[Worcester]

That discolouration line in the first photo (first post) shows a very similar line to the shadow shown in photo 2 of your latest post - could it be dew / condensation on the panel. or parts of the panel at a different temperature and so showing a colour variation?

 

[whinmoor]

That discolouration line in the first photo (first post) shows a very similar line to the shadow shown in photo 2 of your latest post - could it be dew / condensation on the panel. or parts of the panel at a different temperature and so showing a colour variation?

Nicely put. I might plaigiarise this summary as a final explanation to the customer.

 

[whinmoor]

The customer has just phoned me to say that the "mark" is back. He reckons it's in the same place as previously. I'm not in the area so can't get there to check it out.

 

[Worcester]

What time did the sun come up on it ....?

 

[whinmoor]

What time did the sun come up on it ....?

The sun was shining nicely from 9am til 11am and it's been dull ever since. These panels face a few degrees north of east. The photo you were referring to with the diagonal shading line was taken in the sunshine at about 9:45am yesterday so I guess the same thing would have happened today. It's quite possible the anomaly occurred yesterday but was out or didn't notice it.

He phoned me at 11:45am today to say he could see the discolouration again . He wanted me to go round and view it but that wasn't possible. I asked him if he could tell whether it was wet on the outside of the glass but he couldn't say either way.

It's a bit annoying really as he hasn't finished paying yet. I'd like to get a bit tough with him but we've just taken the deposit for doing his son's house so I don't want to upset the applecart at this stage.

 

[whinmoor]

This was Upsolar's response - presumably from China or Taiwan:

"I focused on the lower cell in the middle that appeared darker, now looking to the last pics I see the different shade that is not following any cell paths.

If any liquid was there, inverter would alarm for insulation problem, can we exclude this possibility since the system is working? This is the only point, I really concern about, because it is for safety reason.

On the other hand, it happened before in country like France and Germany, that modules in the morning have been showing different shade due to humidity on the glass or icing. The other option is soiling on the glass.

We can ask customer if he can take more photos in the morning and at mid-day, also from different angles.

FYI, I have seen only one laminate with humidity inside, but it had been de-laminated."

 

[whinmoor]

The customer has now gone on the roof and taken his own photos. Only this one panel is affected so it's got to be something to do with the diagonal shading. It looks like it's under the glass and I can only presume a reaction to the temperature.

The distance photos were taken at 10:30am and the close-ups at 13:30. It's difficult to tell whether the mark has moved in that time or not.

The was the first time we've used Upsolar. I thought they were a decent brand and worth a try but I might steer clear in the future.