PV solar panel cell discoloration

[BobBoyce]

Several days ago I noticed some discoloration on cells of some of my PV solar panels. This is not the usual variation in the shade of cells, but a whitish bleaching of parts of the area of cell surfaces. The discolorations have sharply defined borders and are mainly clustered around the surface contact areas of the cells.

I took the array down for a closer inspection and cleaning, and it looks like this problem is confined only to the Siemens brand of panels. The glass is clear with no sign of moisture, condensation, mold, mildew, ect growing underneath. All 4 Siemens panels have this discoloration to some degree, and were purchased at the same time.

These panels have been up for less than 2 years at this location, prior to that they spent many years in storage, out of the weather. I have worked with and used PV solar for a long time, and have never seen this type of localized spots of discoloration before.

I did voltage and current tests today, and those panels seem to still have good output power. It was slightly overcast, so I could only compare them against other panels in my array of the same rating. The output was about 90% of rating in these lighting conditions. They actually had a little higher output than the other brands of panels of the same ratings.

This discoloration still has me concerned. The panels are still under warranty, but with the output seemingly unaffected, I doubt that warranty would come into play. My concern is that whatever this discoloration is may ultimately affect the operation and longevity of the panels in the future.

Weather permitting, I'll try to get a picture or two of this and post it so others can see what I'm talking about. I'm curious to see if anyone else has seen this type of discoloration before.

Bob

[mightybooboo]

What model panels and are they single crystal?
Just curious,I may get,or consider, Seimens and would like to know.

BooBoo

[BobBoyce]

They are Siemens M55 single crystal panels. Here is a picture taken before the panels were assembled to the array a bit over a year ago.



Here is a picture taken today of two of the panels.



And here is a closer picture of the upper two cells in the left row of the right panel in the above picture. My digital camera is fixed focus, so the closeup shot is not the clearest, but it is the best that camera will do.



I sent these pictures off to Shell Solar today as well to ask their opinion. They bought out Siemens Solar a couple of years ago. If anyone has any ideas as to what this discoloration could be from, I'd like to hear them.

We had a nice clear day today, perfect solar weather, so I performed tests on all 4 panels. Despite the discolorations, all 4 panels tested out beyond rated specs by 5% to 10%. I'm still worried about this affecting performance and longevity on down the road.

Bob

[mightybooboo]

BoB,keep us updated please.Ive never seen such a thing before.Actually was considering the Shells if I cant get BP solar monocrystallines.Thanks for the post.BTW,looks like acid or alkalai damage maybe?
FWIW my 6 years in use BPs look brand new.

BooBoo

[BobBoyce]

Will do. Still no word from them. I'm going to wait intil next week before putting the array back up.

I have the main part of the array standing against the mounting pole facing the southern sky and strapped in place from behind. Wouldn't want the wind to blow it over and end up with damage to the other panels.

If I have to, I can mount the array minus the Siemens panels for now. It'll knock me down to about a KW, but it's better than nothing. I have 5 more of the 150 watt panels in storage, but they are way too big (39" X 44" each) to add to this array. They need an array of their own.

Bob

[BobBoyce]

Well it took a while but I finally heard back from Shell Solar. Their engineers came to the conclusion that it was more than likely caused by moisture from condensation on the metal contacts that spread out away from the metal onto the surrounding cell surfaces.

They said it would be classified as a cosmetic blemish. Their warranty does not cover cosmetic blemishes, even if caused by poor panel sealing on their part. Obviously it's a problem with materials or workmanship. Since testing showed output is still above the 90% criteria for repair or replacement, there is nothing they will do about getting this resolved. My solution is I will not ever buy any of their products again, nor recommend their products to anyone.

Bob

[mightybooboo]

I guess if the warranty says 90% or better is OK,then when they fall below 90 you get replacement?

Bet they've seen it before too,sure seems like a manufacturing defect,but what do I know?

Doesnt sound good at all though,Shell goes off my list from this point forward.

Thats very valuable info Bob,thanks a lot! :worship:

BooBoo

ps,reading back I see they are Siemens.Ive never really been impressed by Siemens products,so Im not that surprised(just ME folks,YMMV).Still dont like Shell blowing it off though,that still sounds bad and I will stay away from them for that reason.

Anyone else have SHELL panels that can chime in here?Their SQ-80 looks like a clone of my BP panels.Would like to hear of warranty issues if youve ever had any.

[BobBoyce]

Shell still sells the M55 under the Siemens name as well. They now only offer a 10 year warranty on these panels. When I bought mine, it was a 25 year warranty. I was told that my warranty is now 10 years as well. Nice to know that I overpaid for a "good" warranty that is now totally worthless. I can buy the same panels retail now for a lot less than I originally paid for these wholesale. I've had these for so long that they would be out of warranty by now at 10 years.

I have had most of my panels in dark storage to prevent decay for about 7 years before putting them in use here. We were too busy trying to get the land paid for, prepped, and a house in. I didn't pull the panels out of storage and assemble the array until a little over a year ago.

If they had sealed these panels properly, then moisture should not have been able to get in there to do damage. Granted we get a lot of cold weather and freezing temperatures, but the other brands of panels exposed to these exact same conditions have not done this.

Bob