From: John De Armond
Newsgroups: alt.energy.homepower
Subject: Re: advice on broken solar panel
Date: Wed, 18 Jun 2008 19:30:00 -0400
Message-ID: <ci5j54hdjbo00ml94i6hi4ik9nrq0bk1ac@4ax.com>

On Tue, 17 Jun 2008 10:16:34 -0700, "Ulysses" <eatmyspam@spamola.com/> wrote:


>I would be worried about the resin leaking through the cracks and making a
>big mess out of the whole thing.   Plus I've seen some clear resin turn
>yellow.  Do you have enough room to just put another piece of glass on top
>and seal the edges with some clear silicone?
>

Everything that has been suggested so far will either solarize (turn yellow)
or quickly decompose under sunlight.

Here's what I'd do.  I'd carefully cut away the broken glazing, leaving an
inch or so around the edges.  If it is glass, cut it with a glass cutter.  If
plastic, a scoring tool made to cut acrylic is available at Home Depot.

The remaining inch is used to cement a replacement glazing to.  I'd go to a
sign shop and buy a piece of clear >>UV stabilized<<< polycarbonate sign
plastic.  This is a laminate, the outer layer of which is a UV absorber.
Regular polycarb also quickly solarizes. GE guarantees their stabilized
polycarb for 10 years of direct sun exposure.  Let the sign shop cut it to
shape to save some work.

Bond that sheet to the perimeter using RTV*.  Why RTV? So that when the
polycarb finally does solarize, you can un-glue it easily.

A custom cut piece of tempered glass would be a good alternative but it likely
will cost more than the panel.  I would not use regular glass unless there is
absolutely zero chance of hail where you live.

The reason that I suggest bonding to a perimeter of old material instead of
just covering the whole case is that undoubtedly the original glazing mount
was designed to accommodate thermal expansion.  Bonding to the case may result
in a mis-match of expansion enough to make the seal fail.

* The hazard to copper of moisture-cured RTV, the kind that gives off acetic
acid fumes, is grossly exaggerated or perhaps just a fiction that's become a
truism.  I couldn't count the number of PCBs that I've potted in moisture-cure
self-leveling RTV, including some that are undoubtedly still in service at a
nuclear plant.  Like most urban legends, there is probably a kernel of truth
there somewhere - undoubtedly someone somewhere had problems under
pathological conditions or perhaps some other contamination caused the problem
- but it is certainly not as serious as commonly believed.

I do NOT like the "Silicone II" stuff.  It's picky about curing (look up the
data sheet and see how many things "inhibit cure" and it's not nearly as tough
as the old stuff.

From: John De Armond
Newsgroups: alt.energy.homepower
Subject: Re: advice on broken solar panel
Date: Sun, 22 Jun 2008 08:15:03 -0400
Message-ID: <kegs54d0a5sg912secj33ep274nkj4jgdp@4ax.com>

On Sat, 21 Jun 2008 10:55:59 +1000, "stu" <nowhere@justyet.com> wrote:

>> A custom cut piece of tempered glass would be a good alternative but it
>> likely will cost more than the panel.  I would not use regular glass
>> unless there is absolutely zero chance of hail where you live.
>
>If the rest of his panels have normal glass, why not use laminated glass?

Because laminated glass breaks just like regular glass.  The only difference
is, the pieces don't go flying.  Neither tempered glass nor Lexan will break
unless the hail is the size of Volkswagen and tempered glass may not break
even then.

John