Introducing holes to roof with solar panel

[tunnelboy]

Kind of a newbie with a 2011 16' Bambi. I have a solar panel system, and managed to find room on the roof to place it. The big question is how to do it!

I have done some reading, and it seems some people are using 3m tape, but I just don't feel comfortable using tape or adhesives alone. I don't want the panel ending up in someone's windshield behind me.

Are there certain locations where brackets should be placed? Like studs? If so how do I find them? Are they wood or metal? If not, do I use sheet metal screws and caulk? How about heavy duty pop rivets? It's scary as heck drilling into this thing, but I don't see any other solution.

Someone somewhere mentioned the possibility of mounting it on top of the A/C shroud, but the solar panel is about 20x46" and I can see a gust of wind tearing that thing off the relatively small footprint of the A/C unit.

I *was* toying with the idea of just pulling the panel out and leaning it against the AS when camping and "locking" it to the frame, but I want a more no fuss solution.

Thanks in advance!

Sam

[idroba]

Use the 3M tape. Done properly it will never come off. The world has changed, and adhesives are long term solutions now.

[AtomicNo13]

In reality, you'll tear the aluminum skin before the panel will fly off!

[lewster]

Originally Posted by tunnelboy

Kind of a newbie with a 2011 16' Bambi. I have a solar panel system, and managed to find room on the roof to place it. The big question is how to do it!

I have done some reading, and it seems some people are using 3m tape, but I just don't feel comfortable using tape or adhesives alone. I don't want the panel ending up in someone's windshield behind me.

Are there certain locations where brackets should be placed? Like studs? If so how do I find them? Are they wood or metal? If not, do I use sheet metal screws and caulk? How about heavy duty pop rivets? It's scary as heck drilling into this thing, but I don't see any other solution.

Someone somewhere mentioned the possibility of mounting it on top of the A/C shroud, but the solar panel is about 20x46" and I can see a gust of wind tearing that thing off the relatively small footprint of the A/C unit.

I *was* toying with the idea of just pulling the panel out and leaning it against the AS when camping and "locking" it to the frame, but I want a more no fuss solution.

Thanks in advance!

Sam

Sam,

It's your trailer and you can, of course, proceed as you wish, but I have personally placed over 1000 solar modules on RV roofs over the last 10 years of installation and have yet to loose a single one. The great majority of those were bonded to the roof using 3M VHB tape and SikaFlex 221 sealant. The only panels that get mechanical fastener (screws) are those for any non-smooth surface like EPDM rubber or TPO and those with bubbly paint or other roof coatings.

Proper surface cleaning and preparation are key to getting the right bond from VHB tape. Once it's stuck down correctly……no worries! I have seen and removed many dealer installed panels that were screwed to Airstream roofs that were no where near as solid as my bonded panels!!

NO HOLES!!!

[WayneG]

Maybe it was overkill but I used the 3M tape that came with the AM Solar rocker mounts and I also used 2 screws in each mount on my motorhome. I don't care about losing a panel, I worry about what it could do to someone behind me.

I do believe properly applied VHB tape could probably handle the panels on its own. I use it for a lot of other internal RV fastenings.

My concern is that the 3M VHB tape looses about 50% of its shear strength when the surface temp gets to 150F. Except for the high end VHB tape the max long term temperature is 200F.
I am not sure what the skin temp gets to in desert country, but I bet it is over 150 all day long.

Being in the East, my bigger worry is that with the small footprint of the mounts and not all of them being over a rib or seam, if excessive snow accumulates on the panels, they could cause a skin dent at weaker mounting points.

[SCOTTinNJ]

Originally Posted by WayneG

Being in the East, my bigger worry is that with the small footprint of the mounts and not all of them being over a rib or seam, if excessive snow accumulates on the panels, they could cause a skin dent at weaker mounting points.

I have been looking into solar panels and while I haven't purchased or installed them yet, I assume you could buy a second set of feet and rotate them 180 degrees so you effectively double the contact surface area. If that would work it might mitigate some of your denting concern while also doubling the bond area.

[lewster]

I appreciate the over building of your installations, but consider that AM Solar has been using VHB tape with their current mounting foot system for over 15 years and they, being the designers and manufacturers of said system, have had no problems with it.

I would venture a guess that over that time frame, they have placed over 5000 solar panels on RV roofs, which translates to over 20,000 individual mounting feet!

No issues!!!! I would consider that a pretty good track record..............no?


Lew Farber
RVIA/RVDA Nationally Certified Master Tech
ABYC Certified Master Marine Electrician
Master Tech Energy Systems, Inc.
AM Solar Certified Installation Center*AMS Lithium Batteries
Lifeline AGM Batteries**Magnum Inverters
541-490-6357

[SCOTTinNJ]

Originally Posted by lewster

I would consider that a pretty good track record..............no?

Not disputing. Just offering alternatives to the OP who wants "belts and suspenders."

[Drathaar]

AM Solar has video on the 3M tape installations.

[rodsterinfl]

Don't worry about using the VHB tape and sikaflex. The two together are amazingly strong and... No holes!

[Outbackga]

Is there a specific 3M type number, VHB means Very High Bond, but there seems to be several types.

Dave

[drboyd]

I believe Lewster 100.00% when he say he has installed zillions of them with no problems.

That said, I live in Arizona, and my experience with any kind of adhesives in the summer sun has not been encouraging. I mounted my panels with stainless steel RivNuts, and stainless steel 1/4x20 socket head cap screws - all sealed with Sikaflex.

You can spot the "studs" easily - that's where the lines of skin rivets are. The closer to get to a stud, the better.

[tunnelboy]

Ok, you sold me! After the first reply, I searched for "solar" and "3m" and saw another debate on here about it. Will skip the piercing of the roof.

A few questions:

1) 3M VHB makes various numbers and sizes. Which number do I want? And any particular width? I assume I want maximum coverage under each pad. I live in N. Calif, and don't plan on going too far with it, but may see freezing temps in the Sierra's or possibly desert conditions on rare occasions.

2) Do I just slather on this Sikaflex over and around the pads? Do I wait for the 3m tape to "cure" a few days or do it right after applying the pads with the tape? How thick and how much coverage past the pads?

3) Prep. Some said alcohol, some said acetone. Should I bother roughing up the pads with fine sandpaper or just clean? They look like they are galvanized steel Z like brackets.

Thanks for the help! Who would have thought?

[WheelnStones]

Ditto, which VHB tape do we want? Tunnelboy, Lewster says do not use alcohol, use mineral spirits or carb/brake cleaner.

[AtomicNo13]

I like to wait a couple days for the adhesive to nano adhere to the surface.

[lewster]

Originally Posted by WheelnStones

Ditto, which VHB tape do we want? Tunnelboy, Lewster says do not use alcohol, use mineral spirits or carb/brake cleaner.

I believe it's VHB 4950, but I will check tomorrow to be sure.

Alcohol is great for the tape alone…... but NOT FOR SIKAFLEX, as it inhibits the bonding strength and the curing process (per Sika Corp. tech support). That's why I only use Carb cleaner……..always! It has never failed me.

[ghaynes755]

AM Solar told me they use VHB 4950. Got that a couple of years ago from Roger at AMSolar. You can get rolls on Amazon.

[WheelnStones]

4950 it is!! Thanks