Friends:
We were called to resolve problems with an off-grid PV install done by
others. The installation is 18 200 watt GE modules about 6 years old. The
modules are direct mounted on S5 clips in strings of three. We found half
of the modules were in failure. A few showed signs of heat damage in the
connection box but most did not. The failure mode is that the voltage was
reduced by 1/3 or 2/3, indicating failed internal strings.
The owner had soldered in some replacement diodes on a few modules. Being
solder in diodes, these do not seem like they are intended to field
replaceable so I did not offer to test or replace them.
The owner had also reported that the installer had come back after a
failure and worked on the wiring but did not describe exactly what was
done. Each string had a home run but all wiring was laying on the roof
with many taped splices.
Several of the modules exhibited a fluctuating output voltage when the
frames were flexed and even changed voltage when laid flat versus tipped up
for testing.
We removed the defective modules and reinstalled the remaining with new PV
cables connected directly to j-boxes and conduit back to the combiner.
I am wondering why so many of these modules failed. I have tried to deduce
some scenario that would explain this, including any mis-wiring
conditions. I am also wondering if modules direct mounted to S5 clips in a
very hot environment (Paso Robles, CA) could cause over heating.
Does anyone out there have any idea as to what may have caused these failures?
Thanks in advance for any wisdom passed my way.
William Miller
Miller Solar
Voice :805-438-5600
email: will...@millersolar.com
http://millersolar.com
License No. C-10-773985
_______________________________________________
List sponsored by Home Power magazine
List Address: RE-wrenches@lists.re-wrenches.org
Options & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
List rules & etiquette:
www.re-wrenches.org/etiquette.htm
Check out participant bios:
www.members.re-wrenches.org
