[RE-wrenches] GE 200 watt module failure

[William Miller]

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: william at millersolar.com
http://millersolar.com
License No. C-10-773985