[RE-wrenches] Commercial Project Performance Issue, Ground Fault, Bypass Diodes or something Else?

[Ryan J LeBlanc]

Is is possible that an un-meggered 11-String PV Output Circuit (CB to Inv),
that gets scuffed during a pull, inside PVC pipe underground could be
leaking to ground (the earth, not the wire), through say water in the pipe,
but not trip a Satcon 210 GFI?  

We are seeing a systems' performance drop off out of sync with a very
similar sub-array on site.  System is in High Dessert with snow around, a
hypothesis is perhaps that a fault occurs, allowing the rest of the
paralleled CB's to also leak into ground (the earth, not the wire), without
the inverter noticing, reducing overall performance.

Another theory might be that some of the SolarWorld mods may have faulty
bypass diodes, consuming some of the power by way of heat.

We took a FLIR around the site, and saw on one module we checked that had a
bit of shading at the time, had a cell that was 120°F while the others were
90, and then 80 as you got away from that cell.

Is this a normal temperature when the bypass diodes are working, and just
the cells in the string are feeding the shaded cell, or is this unusually
hot, perhaps caused by a faulty, or missing diode?

Any help is appreciated.     
  

Ryan J. LeBlanc
NABCEP™ Certified Solar PV Installer
Cell: 707.591.1950
Direct: 707.536.9839
ryan at NaturalEnergyWorks.com
http://www.NaturalEnergyWorks.com