Panels with small strange spots

[molle the man]

I made an order from a manufactorer and more then half of the panels had four small brown spots on each cell and it looks almost exactly the same on every panel that have this. The spots are very small and brownish, and they sit at almost exactly the same places on all cells and on all these panels, just slightly diagonal from the spot on the cell above and under. does any one know what this can be?

[silversaver]

No brand name panels? Probably the soldering point from cell assembly or burn mark from the iron

[molle the man]

Its from a mayor brand, i will reveal it when the replacement process is over to not spread badwill before I know how they will handle this. The question is, would they work?

[Mike90250]

generally, when you purchase bare cells, you get 2nd's from the production line, the prime #1 cells go to panel assembly houses.

I would expect them to work, the discoloration is only a small % of the surface area,

[MGE]

My Suniva 260w panels had them on a couple when I did my install 3 years ago. Not a problem they all work perfectly. Probably a solder burn as suggested, nothing to worry about IMO. Your going to replace them?

[solarix]

This is not a common problem and you are right to raise the issue at installation rather than waiting on the off chance that this is an actual problem. Please let us know (someday) who the manufacturer is....

[littleharbor]

Those spots are most likely inherent to the automated manufacturing process used to mass produce multicrystalline cells. I buy and sell solar panels and have noticed these markings on many panels from many different mfg. They (the markings) are all located on the same area of every cell in many A grade modules I have seen.

[solnoob]

When you refer to the process used to mass produce the multicrystalline cells, are you referring to doping specifically?

"Doping - The traditional way of doping (adding impurities to) silicon wafers with boron and phosphorous is to introduce a small amount of boron during the Czochralski process in step #3 above. The wafers are then sealed back to back and placed in a furnace to be heated to slightly below the melting point of silicon (2,570 degrees Fahrenheit or 1,410 degrees Celsius) in the presence of phosphorous gas. The phosphorous atoms "burrow" into the silicon, which is more porous because it is close to becoming a liquid. The temperature and time given to the process is carefully controlled to ensure a uniform junction of proper depth.

A more recent way of doping silicon with phosphorous is to use a small particle accelerator to shoot phosphorous ions into the ingot. By controlling the speed of the ions, it is possible to control their penetrating depth. This new process, however, has generally not been accepted by commercial manufacturers."

[littleharbor]

I say multicrystalline because I don't notice these marks on Monocrystalline cells, But of course mono cells are produced differently.

[molle the man]

Those spots are most likely inherent to the automated manufacturing process used to mass produce multicrystalline cells. I buy and sell solar panels and have noticed these markings on many panels from many different mfg. They (the markings) are all located on the same area of every cell in many A grade modules I have seen.

So in the panels that you have seen before, have there been any problem with them?


"This is not a common problem and you are right to raise the issue at installation rather than waiting on the off chance that this is an actual problem. Please let us know (someday) who the manufacturer is...."

The reason I cant turn to the installer is becouse I am the installer, and this happends on my first project I am dealing with the mfg at the moment have have been given a few options, will let you all know how it played out when project is complete.


Then next question for you guys, do you know any god way to test panels,

there is a guide here https://www.solarpaneltalk.com/priva...cation/25016/1

but it only deals with the open circut voltage,

[littleharbor]

No problem. These are new A grade modules. As I said I believe this comes with automated manufacturing being that the small spot is on the exact same location on every cell. If you had a stack of factory wrapped cells you would see the marks all lined up on the edge of the cells in the stack.

[solnoob]

Were you able to ID the issue or get it resolved?

[ncs55]

They look like blemished modules or seconds. Blems can be visual or electrical related and usually have a sticker on the back Identifying which type. Did you get a smokin deal on them? I see the same thing, even cracking of the crystalline and they test fine. But will they last? Willing to gamble with your customers money? If you were sold a blem then it was up to the seller to notify you of that. The module in this picture had 9 out of 60 cells like what you see and was producing within its specs, however it is only a few years old and we are monitoring it and the others like it.

[gendil]

every body look at picture of ncs55 that is the same as my case ....the panels still work ....but what is this ,,,hotspot?....snailtrail? or microcrack? what cateorgy it is ..? and how

serious it is ??

[Mike90250]

Looks like a crack in the wafers and burned spots. Either the panel flexed and cracked, something hit it, or bad from factory and just needed some heat to show it up.
Bummer.

[gendil]

how frustrated i am ...it is just 5 months of work ..by the way i am not fixing my panel to any thing just i put it vertically along the roof "i have vertical roof "

and at the start of december and the cold weather and some rains ...i saw those lines ....before in the hot days it was just fine ...so sir it is not heat related ...it is either

water--humidity or cold related failure....by saying failure i am exaggerating because tests shows that still the panel prodcuing its promised output