Brian,
I was general manager of 2 solar factories. There is lots of literature
about EVA and moisture. For example
http://www.nrel.gov/docs/fy02osti/30841.pdf
I am sure moisture (H2O) can enter laminates from the edge. EVA does not
protect the cells from moisture. EVA provides a path for moisture to wick
into glass and non-glass laminates.
Frameless laminates are laminated the same way as framed modules. The
laminate seal and the distance that moisture must travel from the edge of
the laminate to the cell, grid, and interconnects are the only protection
from moisture. Most manufacturers use a gasket held in place by the frame to
protect and seal the laminate edge.
Dow 739 and other room temperature vulcanizing (RTV) silicone elastomers are
good for edge-sealing laminates and fastening and sealing junction boxes.
Joel Davidson
----- Original Message -----
From: "Brian Teitelbaum" <[email protected]>
To: "RE-wrenches" <[email protected]>
Sent: Wednesday, June 24, 2009 5:42 PM
Subject: Re: [RE-wrenches] module frame separation
Joel,
Are you sure that water can enter the laminate from the edge? My
understanding is that the aluminum frame is only needed for structural
support, and that the laminate itself is sealed at the edge. I'd like to
know if I'm wrong. Maybe a module manu rep can chime in.
How are frame-less laminates edge sealed in any way different than a
framed module?
I know that in years past, when we had long and skinny modules, it was not
uncommon for installers to remove the bottom part of the frame in order to
allow better snow and dirt shedding (although I certainly wouldn't suggest
that with today's large glass).
On the silicone sealant: Best to use one that does not outgas acetic acid.
Dow 739 is one type, but there are others. These sealants are 100%
silicone, and are hydroscopic, in that they draw water out of the air for
the curing process, instead of the more usual silicone caulks that cure in
a chemical process that outgases acetic acid as a byproduct. It's really
nice stuff to work with, since it doesn't have that harsh smell, and is
really easy on the skin (mine anyway).
I don't know if acetic acid will damage any of the modern encapsulates,
but I used to keep a tube of 739 in my toolbox to seal damaged back skins,
and seal module's JB's. I do know that acetic acid can damage metallic
parts, including cell metallization and internal JB metal parts.
Brian Teitelbaum
AEE Solar
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Joel
Davidson
Sent: Wednesday, June 24, 2009 2:00 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] module frame separation
William,
The main concerns are physical damage to the unsupported laminate and
moisture penetration at the exposed edge of the laminate. If the frame can
be pushed back in place without breaking the laminate, you can fasten a
flat
bar across the back of the module to keep the frame in place. EVA is
hydroscopic and moisture will wick into the laminate from the exposed
edge.
Run a bead of silicone caulk along the edge of the laminate before
securing
the frame back in place.
Joel Davidson
----- Original Message -----
From: "William Korthof" <[email protected]>
To: <[email protected]>
Sent: Wednesday, June 24, 2009 1:39 PM
Subject: [RE-wrenches] module frame separation
Recently we've had a few modules (~5 year old) exhibit frame separation
from the glass...
in one case, it's minor separation of the long edge of frame on one or
both sides of a few modules... the frames seem okay and reasonably
secure
when attached on the roof, but were loose during handling.
In another case, the customer is located in snow-impacted mountains.
Apparently, a sheet of icy snow pulled the bottom (short) edge of the
frame apart from the glass and side frame pieces. No damage to the
glass,
but the lower edges of 6+ frames are now dangling by a thread.
I don't think the module warranties cover this problem---the power
output
remains within spec and there is no evident damage to the glass. But if
we don't provide some sort of repair, the modules will break.
Any suggestions for this kind of repair?
What kind of glue would we use to reattach the glass to the aluminum
frames?
Thanks,
William Korthof
Energy Efficiency Solar
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