Panels with small strange spots

[pvexperience]

IMG_20191128_130152489.jpgIMG_20191128_130007635_MP(1).jpgIMG_20191128_130207877.jpgIMG_20191128_125856794_HDR(2).jpg Should I replace this panel that has burn marks? What is the best way to test its performance? Will this limit performance of just this panel or the entire string? There are 14 of these in series and another 14 in series, those 2 strings in parallel to a SMA SB7000. They have been in service since 2014

Don't know about the warranty from back then, but it is currently normal to have a 10-year workmanship warranty, and it looks like just that, a workmanship problem. The backsheet is open to the world, and it is designed to protect people from getting electrocuted. This should be replaced ASAP (I know this reply is years late, but better late than never). My bet is that the backside ribbon is significantly offset from the cell, because that is a very unusual place for overheating on a cell.

[pvexperience]

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?

Sorry for the late replay, just getting on this forum. These look like shadow marks from the PECVD process. This is the process that deposits the thin layer that makes the cell look blue.

[montana]

Warranty seems to say free from defects for 12 months and after that, only warranty if does not produce rated power. Also says to initiate claim through vendor I bought them from, which was from EBay, also says I pay freight both ways. So I have very dim hopes for a warranty replacement. Does anyone know best way to test power output, I have not tested open circuit voltage yet. I am less concerned if it is only affecting this one panel , I guess maybe I should take the one panel out of the string and see if the 7000 watt inverter makes more power with or without it. Shipping makes replacing one panel kind of expensive, also would need to find a panel that is the exact same width. https://www.energymatters.com.au/wp-content/uploads/2014/08/sharp-warranty.pdf This may not be the correct warranty document.
I attached a trend of the SB7000 production, the inverter with the burnt panel is the blue pen (28, 240 watt panels), The cyan pen are 28, 250 watt Q-cells, the red pen are Sharp 28, 240 watt panels but they are roof mounted at a shallow angle and make less power. The angle of the ground mounted Q-Cells are about 2 degrees steeper vs the ground mounted Sharps. Average power production delta between the ground mounted Q-Cells vs Sharps is now about 420 watts and was very similar in 2015. So power production does not seem to be greatly affected yet.

SB7000 Watts.png

[Mike90250]

That would be a warranty replacemet, the cells should not crack and scorch the backsheet. If something impacted the backsheet, that could crack it

[montana]

IMG_20191128_130152489.jpgIMG_20191128_130007635_MP(1).jpgIMG_20191128_130207877.jpgIMG_20191128_125856794_HDR(2).jpg Should I replace this panel that has burn marks? What is the best way to test its performance? Will this limit performance of just this panel or the entire string? There are 14 of these in series and another 14 in series, those 2 strings in parallel to a SMA SB7000. They have been in service since 2014

[gendil]

no it is Chinese made panel ...bought it from company that offers solar panels ...however because i install it my self i doubt they offer any warranty...so i am alone in this

problem ..i will just wait till it really dies ...0 volts ...then i replace it or fix it if that is possible ...i have installed smaller panels no-name chinese panels before none showed this

symptom however i noticed the following


all the ones i bought before were small panels around 60 watt or some thing they worked fine now i store them in my storage room it is time to pull them out again


so the psychical size make it easy for those to large "250 watt panel " to crack

at least that what happen with me and that is my experience with those panels ...i should have bought 2 100watt instead of one large 250 watt

[Mike90250]

Is this a home made panel with surplus cells ? The cracking will never heal itself, and will only get worse,

[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

[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]

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 ??

[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."

[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.

[solnoob]

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

[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.

[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,