Question - adhering flexible solar modules

pbjosh · 01-28-2015, 10:45 AM

Hey there,

We finally raptor-lined our poptop and have a pair of flexible TPT backed solar modules. This isn't the module we have, but it's very similar and the materials are the same:

http://www.carid.com/carmanah/go-pow...FYlefgodcg4A1A

I am going to glue down the panels. We have Euro friends who have adhered their panels with Sika 252. The (very helpful and highly recommended) gentleman from whom we bought our solar bits, Larry at Starlight Solar (http://www.starlightsolar.com/Home.html), recommended we use Loctite S30 Polyurethane Roof & Flashing Sealant. I am going with glue-only, and he said that he also screws through the grommets but that the glue would hold fine.

My gut says scuffing the back of the panels for adhesion and Sika 252 is the way to go, but I'd love opinions if others have done this.

I'm also planning on sealing around the edges of the panels with self-leveling dicor to keep them from collecting crap and to keep things from running under them in the channels.

Cheers,
Josh

JackTuppVan · 01-28-2015, 05:39 PM

If this were my project i would not glue the solar modules directly to the penthouse top. Reason being if the solar modules failed for any reason it would be nearly impossible to remove with out damaging the raptor lining and possibly the top itself. and if the solar modules come with a warranty i would imagine they would have to be returned in order to be replaced. What i would do is attach the solar modules to a piece of sheet metal /aluminum . On the penthouse top i would fab up some strips to fill the recesses / channels under the aluminum panel now you have a level mounting pad. I would choose composite decking material for the strips ( this material can be planed to the desired thickness on a wood planer ) and then would bevel the leading and trailing edges, glue these strips into the channels. Now you can screw/glue the aluminum backed solar modules directly into/ onto the strips

pbjosh · 01-28-2015, 06:11 PM

Thanks for the thoughts. I have three desires in gluing the panels down (not that I can't be talked out of it):

-Lowest profile possible, fitting in a container for international shipping (we are already alarmingly close to the door height on a 40' tall cube and will most certainly need to air down). We are taking the van to
South America for 2-3 years and, for security reasons, absolutely won't ship RORO (roll-on roll-off, everything that isn't glued down is stolen, inside and outside the vehicle, it happens to everyone despite what the ports and shippers will say).

-Lowest profile possible, to avoid damage to panels or any chance of panels tearing off or catching a leading edge on branch scrapes, which will happen. We are field biologists and birders and are in the forest and jungle all the time, that's why we are building the vehicle.

-Making it impossible for the panels to get stolen. There are a lot of things just bolted onto a Sportsmobile and, if you get unlucky, thieves are pretty clever. I DOUBT panels that appear adhered would get stolen even if they technically are removable, but if they look like they're just bolted/screwed on, I would worry about them disappearing. (Along this line I'm currently still mulling over how to reasonably keep tension on a winch cable while taking the hook off and sucking the rope back inside the bumper so the hook doesn't get stolen. I thought about welding or otherwise making permanent the clevis pin on the winch hook but I have a synthetic rope and it would really suck if someone cut the rope to get the hook, but that's a different discussion).

In any case, I know it would be ghastly to get the panels up. If there is a broken panel, I'll be less worried about the warranty issues than the difficulty of removal and potential difficulty of replacing the panel with a similary spec'd panel, which will be my primary concern...

Cheers,
Josh

JackTuppVan · 01-28-2015, 10:21 PM

Josh , Sounds like you are embarking on an adventure of a lifetime . Addressing the low profile concern ,what i was proposing would only increase the height the thickness of the sheet metal /aluminum used ....approx .060" (thickness of a street sign) . You can apply the adhesive only to the strips (no screws). Concerning the winch hook problem this may be a solution http://www.amazon.com/Factor55-ProLink- ... B00KDJ94A0

rockbender · 01-28-2015, 11:09 PM

I'll likely be adhering a panel or two this spring and had planned on using 3M VHB tape. I know others have used this with success on solar panels and roof rack rails as well. I like your idea of sealing at a minimum the leading edge of the panel to prevent crud from accumulating underneath.

Please let us know which way you go!

JWA · 01-29-2015, 06:28 AM

Were this me I'd follow the suggestions where the flex material is first bonded to a substrate which would then be affixed to the body. Ease of removal if replacement or service is ever required would be monumentally important.

I'd use either a liquid adhesive spread completely over the substrate for maximum adhesion without gaps between the two pieces. While the 3M VHB tape would be good even at its thinnest it still raises the flex panel above any substrate which could be problematic.

If going the liquid or spreadable adhesive route make sure the material is compatible with the flex panels.

Scalf77 · 01-29-2015, 07:16 AM

This was one of the nicer flat panel installs: It may give you some more ideas. In the end you may just need to follow your gut.

http://www.sportsmobileforum.com/vie...11&hilit=solar

-greg

pbjosh · 01-31-2015, 10:25 PM

Hello again folks,

Sorry I haven't responded in a day or three. Been busy crimping and welding and hole cutting and spray gluing vinyl and all the other fun stuff that goes into actually finishing a build! Also just made a final todo list. They're all small things, but man there are a lot of them

I've been reading along but waiting until I had time to chime back in. I really appreciate the thoughts.

Jack, thank you very much for the Prolink info. I hadn't really looked into that can of worms yet. That is EXACTLY what I am looking for, solves the problem elegantly - gets the synthetic rope out of the sun, avoids winch hook theft, a shackle is more secure than a hook, all around looks great. It's a bit spendy but it's a specialty product and I really, really like it when you can solve something well, it is worth paying for.

In any case, back to panels, I fully understand all the thoughts about the perils of gluing down. But gluing down something in the channels on the roof, then using shallow mounting screws into that, doesn't float my boat. If you're going to glue into the channels THEN glue onto the stuff in the channels, might as well just glue the panels to the roof and eliminate a step, some weight, and an extra layer to bond. As far as a sheet of material in between - bonding aluminum, despite all manufacturer and adhesive recommendations and ratings, is non trivial, and I have a bit of experience there, we've built our entire van of aluminum and plastic. If I'm going to glue down, it might as well be the panels instead of a sheet of 5052. I want panels to stay on, bar none, take a beating, and not be able to be torn off. We absolutely, 100% positively, will thrash these panels and will hit them with hanging branches, perhaps hanging wires, and who knows what else. They will be dirty, they will be covered in bird shit and mud and grime and who knows what in between cleanings, and they will get rained on for hours per day, every day. I want the cleanest, strongest, lowest profile adhesion possible. I don't think screws are necessary, but I am fairly convinced that glue directly to the roof is.

I realize glue down is (relatively) permanent. It could take many blades and many many hours or perhaps many days to cut the adhesives should I need to remove a panel, but I've tested the panels well, they are well vouched for by the vendor I purchased them from (whom I trust quite well), and if there is an issue, we are going to be a long way from a replacement panel anyways. Instead, we'll move to alternator charging or 1 panel charging should a panel crap out. I'd rather have peace of mind and spend 3 days carefully cutting Sikaflex than I would worry about a multi-layer mounting system or screws and leaks in the roof and things getting torn off. It takes a bit of commitment to glue down. I have that commitment, I'm just not sure of glue yet. I sort of have "two best options" as recommended by various people who have succeeded in using the products - Sika 252 and the Loctite S30. I will call both manufacturers, we'll see what they have to say.

I assume (and it's a HUGE assumption) that it is easy to adhere to bedliner. There is plenty of texture there! But realistically, it is just an assumption.

I will do a test adhesion with a line of each adhesive on my roof to a panel soon. I'll clean and prep correctly, press them both in, anchor / clamp / insure good conditions for curing, and in a few days I'll try to rip them up or if necessary cut them off. I'd rather tear Raptor-liner off my roof, or risk tearing a panel now, and know what's going to work, than I would glue down and cross fingers that nothing can go wrong long term.

Again, if anyone has used Polyurethane flexible curing construction / roofing adhesives or any other adhesives to fix things to a Raptor-liner covered roof, or has adhered TPT backed flexible modules to their roof, I'd love to hear what you used and how it worked out! I've heard of people taping down with VHB type tape, but I don't know much about it, really. More reading for tonight...

Again, thanks all for the thoughts and I don't mind being called crazy/stupid/etc. I really believe in lots of research, lots of testing, then just going with the best solution, even if it sometimes is hard to reverse. I can, almost always, readily remove/fix/re-arrange what I need in the van. But there are things that will be painful to undo if necessary. Thankfully I'm confident in what I've done there, and thankfully beers and patience and tropical weather assuage the frustration of invariably undoing at least one of those things down the road.

Cheers all, I do appreciate any and all information shared!

Josh

JWA · 02-01-2015, 06:30 AM

Josh in the end this is your van so your choices are what you believe will work best for this from start to finish.

Like anything else if the so-called downsides of any of our suggestions don't pose any problems that's fine---after all you were asking for suggestions not necessarily the one and only way to tackle your solar panel install.

Hope to hear of your progress and maybe see some photos too!

**daveb** · 02-01-2015, 10:29 AM

My Solara panels were glued down and they worked fine until the panels failed. That took a few years. It was a bit of a job pulling them off but doable. I would of had to re-gel coat the top but went the rhino lining way and put glass panels up. I'd never go with glass panels on a venture like you're planning for reason you've stated. I don't know how well a flat panel would stay down on a fully sprayed top but you could always just spray around them if it turns out to be an issue. Sure wouldn't want to find out they stick poorly on a sprayed on roof out in the field.