[RE-wrenches] PV panel backing

[Martin Herzfeld]

I concur with Dan.  Unless a controlled environment, a patch job on a
module with a customer is wrong on so many levels.

Martin Herzfeld
California Solar Contractor License  #833782
Trenching Contractor, Pole Installation & Maintenance, Instrumentation

UL Certified PV Installer #17, OSHA 30
Principal Contract Solar Technical Inspector
OSHA-Authorized Construction Trainer
CompTIA Certified Technical Classroom Trainer (CTT+) #T3NSZCNBBKB4QTQG
Project Contractor & Consultant

Telephone & Text: 510-243-0190

Ron,

It's been my experience the only adhesives that work reliably on PV
backsheets are those designed for the purpose, such as Dow 804 et. al..
Substances such as silicone sealant, tool polymerics, and others will
appear to be suitable when first applied, but they eventually peel loose
over a period of 1-5 years.

Issue #2: Heat of sufficient temperature to melt the backsheet may also
have been hot enough to affect solder joints on and among the cells.
Crystallized solder connections will conduct current, but are more
resistive, and eventually will degrade due to heating and cooling, leading
to overheating and eventual failure.  Then too there's a possibility of
micro-fractures created in the cells due to the heat, which take time to
become apparent, but will also cause a PV module to quit working .. or at
least quit working at its rated specifications.

Issue #3:  When PV are manufactured, the layers at a minimum are
manufactured from tempered glass, EVA, cells and buss, EVA, then the
backsheet (tedlar, kevlar, etc.), in that order.  The module is assembled
under conditions of heat and vacuum.  With the backsheet melted, the
environmental integrity of the laminate has been compromised, allowing
ambient humidity into the PV.  While it may be functional now, long-term
prospects for continued proper operation are questionable at best.

Unless there's a pressing reason to try to salvage the module, it's better
to replace it.

Dan Lepinski

--------------------------------------------
On Sun, 8/31/14, Ron Young <solareagle at solareagle.com> wrote:

Subject: [RE-wrenches] PV panel backing
To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
Date: Sunday, August 31, 2014, 6:32 AM

Hello Wrenches,

I have an installation of 165w PV on a pole mount that was exposed to a
fire from the rear when the customers shop burned. 6 of the 10 panels
survived with only replacement of the MC4 plugs required but one of the
panels that is still functioning had the rear coating melted off. The cells
and electrical grid still function. Can anyone recommend a replacement
coating that may salvage this panel for a few more years. I know if left
exposed it will soon deteriorate but am wondering if some kind of commonly
available non conductive rubberized or latex type of coating might do the
job?

Ron Young

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