Panels with small strange spots

[Mike90250]

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

[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

[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

[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]

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

[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.

[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.