Poly panel turns black and loses power

DMJ72

Anyone ever see this before?

that string of three (230W Poly panels - Chinese Ningo Quixin) produced half the power of the other 3. When I looked at the cells closely, there is a dark hue over most of them, with loss of the usual polycrystalline variance.

Could this be moisture ingress as a result of a bad seal? the thing is, these panels were in storage until today.

inetdog

Re: Poly panel turns black and loses power

DMJ72 wrote: »

Anyone ever see this before?

that string of three (230W Poly panels - Chinese Ningo Quixin) produced half the power of the other 3. When I looked at the cells closely, there is a dark hue over most of them, with loss of the usual polycrystalline variance.

Could this be moisture ingress as a result of a bad seal? the thing is, these panels were in storage until today.

The color change implies some change in the active surface of the cell. Moisture related chemical action is certainly the most likely and will cause both a visual and a performance change.
Totally excessive heat might also have an effect on the silicon.

PNjunction

Re: Poly panel turns black and loses power

I would verify that there are no blown bypass diodes inside the panel's junction box. Also make sure that polarity was wired up correctly. These things are known to be built on a fast production line.

It looks kind of like reverse-bias overheating, but could be just a blown bypass diode, or one panel that is using a slightly different chemical makeup. Prior to storage, was this one panel always in the shade?

It looks like you are obviously testing them, but be aware of the heat issue - you don't want to set your grass on fire. I'd get some more separation or at least tilt them a bit while testing.

DMJ72

Re: Poly panel turns black and loses power

PNjunction wrote: »

I would verify that there are no blown bypass diodes inside the panel's junction box. Also make sure that polarity was wired up correctly. These things are known to be built on a fast production line.

It looks kind of like reverse-bias overheating, but could be just a blown bypass diode, or one panel that is using a slightly different chemical makeup. Prior to storage, was this one panel always in the shade?

It looks like you are obviously testing them, but be aware of the heat issue - you don't want to set your grass on fire. I'd get some more separation or at least tilt them a bit while testing.

Hi PNjuntion, I returned the panel yesterday for a replacement. The junction box had a security clip on it, therefore I left it alone as I did not want to cause an issue with the warranty. I will definitely take your advice with the elevation.