[Zanshin]

I am installing 2 thin, semi-flexible solar panels on my deck. I cannot source any double-sided adhesive sheets and am going to use 4200 for the installation but have no experience with caulking. I think that getting the panels installed with 4200 shouldn't be too difficult, but wish to make a waterproof seal around the edges of the panels to prevent water ingress and have two questions for those in the know:

- Should this edge seal be done with 4200 or should I use a silicone sealant?
- How can I ensure doing a job which doesn't look like an absolute mess, i.e. smoothing the bead.

 

[Maine Sail]

I am installing 2 thin, semi-flexible solar panels on my deck. I cannot source any double-sided adhesive sheets and am going to use 4200 for the installation but have no experience with caulking. I think that getting the panels installed with 4200 shouldn't be too difficult, but wish to make a waterproof seal around the edges of the panels to prevent water ingress and have two questions for those in the know:

- Should this edge seal be done with 4200 or should I use a silicone sealant?
- How can I ensure doing a job which doesn't look like an absolute mess, i.e. smoothing the bead.

Installing this type of panel direct to a deck is often less than ideal. You can develop lots of heat, which can't escape, and that can leads to lower overall panel efficiency and in some cases early failure.. Some boat builders have tried this and it has created some issues with panel delamination even on custom 2 million dollar yachts.

Also, unless the panel was specifically laminated as a "walk on" I would not recommend you do this. Some panels are rated to be walked on and some others are not.

I would definitely not glue these things down with an adhesive like 4200 but that's just me.. You could sew on some canvas piping, similar to a luff tape, then use the plastic extruded channels to slide the luff tapes into and back the panel with some green house glass (polycarbonate) with the channels in it for air movement..

Still a deck mount for any solar panel would be an absolute last resort for me, due to the heat it creates, which then can't breathe or cool. In a best case scenario you only deal with a delaminated or failed panel sooner than expected but in a worst case you can damage the deck lamination, due to this heat.

 

[IStream]

Even if you don't go with Maine's smart suggestion and decide to glue them down, I would strongly suggest that you not try to make a completely waterproof bead. No glue joint is truly waterproof for long, better to leave gaps for drainage.

 

[Zanshin]

Thanks for the responses.

Oddly enough the panel manufacturer (Solbian) seems to recommend gluing the panels in place on deck. The CP125 panels are meant to be walked on (with the caveat of "no high heels") and the area where I am installing them won't see much, if any, foot traffic.
At the BOOT boat show a month ago I was surprised how many of the production cats now have factory-installed thin solar panels glued in; the one I asked about heat production and insulation said that they foresaw no problems - although they have a vested interest in minimizing issues prior to sale, they do warranty their installations and I doubt that they would intentionally continue with a practice that is detrimental to their bottom line.

I just came back from the canvas show and we'd discussed the luff rope approach, and their issue was with keeping proper tension on the panels over time and if just 2 sides are used for putting them on then wind can get under the panel and cause it to flop around, damaging itself in the process.

I will continue with gluing the panels in place as posted; but the two original questions remain unanswered.

 

[hellosailor]

An interesting dilemma, since the ideal adhesive would have to be both permanent AND removable for maintenance. You might be able to do something like this:
Get a thin (2mm?) sheet of white EDPM (or butyl or neoprene) from Grainger or other suppliers. Spray, carefully, with 3M's permanent spray adhesive. Check with 3M as to which one will be permanent, they're not all the same and not all heat-resistant.
Allow to dry, spray rear of panel with same adhesive. Bond together. Now neatly trim the edges flush, or on an angle (freehand or with a matte cutter) and then spray the new back side with the same adhesive, after making a pattern from the panel.
Solvent clean the deck, use the pattern to mask off an area, spray it with the same adhesive, and carefully lay the panel down. Sandbag to press while it dries.

That should give you a reasonably permanent, completely closed and sealed (no voids to grow mildew), slightly insulated bond between the panel and the deck. More work than 4200 but a way neater edge, and no needed to use a notched trowel or play other games making an even layer of bonding material.

In the worst case if it bonds too well and you need to get in there? The EDPM or other "rubber" will come apart, when you find a big enough gorilla to pull on the panel.

The hardest part will be finding a windless day to do the spraying.(G)

Unless 3M makes their VHB tape in sheet form, already set to go?

 

[IStream]

An interesting dilemma, since the ideal adhesive would have to be both permanent AND removable for maintenance. You might be able to do something like this:
Get a thin (2mm?) sheet of white EDPM (or butyl or neoprene) from Grainger or other suppliers. Spray, carefully, with 3M's permanent spray adhesive. Check with 3M as to which one will be permanent, they're not all the same and not all heat-resistant.
Allow to dry, spray rear of panel with same adhesive. Bond together. Now neatly trim the edges flush, or on an angle (freehand or with a matte cutter) and then spray the new back side with the same adhesive, after making a pattern from the panel.
Solvent clean the deck, use the pattern to mask off an area, spray it with the same adhesive, and carefully lay the panel down. Sandbag to press while it dries.

That should give you a reasonably permanent, completely closed and sealed (no voids to grow mildew), slightly insulated bond between the panel and the deck. More work than 4200 but a way neater edge, and no needed to use a notched trowel or play other games making an even layer of bonding material.

In the worst case if it bonds too well and you need to get in there? The EDPM or other "rubber" will come apart, when you find a big enough gorilla to pull on the panel.

The hardest part will be finding a windless day to do the spraying.(G)

Unless 3M makes their VHB tape in sheet form, already set to go?

I've had good luck with this in other demanding applications, might be worth a try:

Amazon.com: 3M 03616 Scotch-Mount 7/8" x 15' Molding Tape: [email protected]@[email protected]@http://ecx.images-amazon.com/images/I/[email protected]@[email protected]@51XCeXyx2qL

 

[boz86]

Zanshin,

I've read never to use silicon on fiberglass because you can never completely remove it. Which affects future projects.

Regarding the bead, how about a tool like this? STAR BRITE Caulk-Away & Caulk-Rite Caulking Tools | West Marine
I don't know if it'll work on 4200 but they're pretty common type tools for other caulking.

Those are my thoughts on your specific questions but I'm not an expert in this, just offering up what I've read to get more discussion going.