Odd response from 3M about VHB 4950 tape

[woundedpig]

I contacted 3M trying to get some help figuring out how to get appropriate width of VHB to get full coverage of some solar panel mounts I plan to use for some Renogy panels.

I got this response: ? Is this a CYA response? Maybe I should have expected it. I don't know what tape number or how much they use to hold trucks together but it is not 4 sq inches per pound of weight supported.

Thoughts?

David

__________________________________________________ ____________

Thank you for contacting 3M, where we apply science to life.

I am not sure where you heard the 4950 VHB tape is frequently used for this type of application. We do not suggest that particular VHB, and in fact, VHB can be used for this application, but we suggest it in conjunction with mechanical fasteners. VHB was not intended for this application as a sole means of bonding it due to many factors. The 4950 tape is mostly used for metal to metal applications. We have other VHB tapes that will bond much better to fiberglass. I would suggest to test our VHB tape #5962 along with our adhesion promoter 111. We suggest to use 4 square inches of tape, per pound of weight it will support. I have attached the data page for review. Please read over all the application instructions as surface prep, how much tape to use, set up time, etc. is all listed. You won't need to get an exact width of tape for the width of the panels, as long as you can get the 4 sq. inches per pound around the diameter. Also, use the mechanical fasteners in addition to the tape. This is suggested to support the wind loads it will see going down the highway.

You can find these products on Amazon.com, R S Hughes, or Grainger, usually in smaller rolls or broken cases.

If you need further/additional assistance or prefer to speak directly with a specialist please call 1-800-362-3550 for the first available representative.

Regards,

Lisa P.
3M Product Application Support
Industrial Business
1-800-362-3550

[uncle_bob]

Hi

If you have a 50 lb solar panel and go with 200 square inches, that's four strips of 50 square inches each. If they are 48" long they each would be an inch wide. At 36" long you would get up to about 1.5" wide. Overkill maybe. I've had a number of things like this degrade in odd ways at either very high or very low temperatures.

Bob

[RVDreamer]

Originally Posted by woundedpig

The 4950 tape is mostly used for metal to metal applications. We have other VHB tapes that will bond much better to fiberglass.

From the information in the response, it appears they didn't realize you were bonding the panels to an Airstream. They assumed you were bonding to a fiberglass roof whereas Airstreams have a metal roof. That makes all the difference in the bonding strength.

Lewster uses this tape all the time for solar panel attachment to Airstreams and so far hasn't had any problems.

[Al and Missy]

I thought Lewster used UHB tape, a different animal.

Al

[lsbrodsky]

My solar from AMSolar came with VHB tape attached to the feet and that is what Lewster uses, I believe. He also uses Sikaflex to seal and increase adhesion around the feet.

Larry

[woundedpig]

Well, actually - I was considering using VHB 4950 with a new fiberglass roof on a Class C motorhome application because I thought that was the practice at AMSolar. Should have specified that. Big difference.

David

[PDXPaulie]

I just added a panel to the top of my AI. From their website MSDS, 3m VHB 4950 will hold something like 80 lbs per square inch when fully cured. If you're using the Renogy mounts, 4x 1"x4"strips = well you can do the math.

Heres the link. It does say metal, glass, and "high energy" substrates, theres also another sheet that says 4950 is an acceptable application for glass/epoxy substrates. But you can also check with Lewster or call or email Roger at AM Solar.

http://multimedia.3m.com/mws/media/1...alty-tapes.pdf

[Pygmypoacher]

I'm installing 3 160w AMSolar panels on my AS. I stuck with the VHB tape provided by AMSolar but doubled up the feet - two per corner. No screws through my roof!

Sorry about the pun... Couldn't resist.

[WayneG]

The tapes strength is reduced at higher temperatures.
My panel mounts use tape & screws

[guskmg]

I have 8 Panels secured buy lewsters 3M tape and Silkaflex around the foot perimeters. After install, trailer was towed from FL to TX at 80 mph. None have come loose
in one and a half years.
guskmg

[adobehome]

I did the same as others stated above. 3m VHB tape bought from Amazon and Silkaflex around the feet of the mounting system that I made. I installed one panel on roof of my 1962 Globetrotter nearly 2 years ago. I cleaned the metal of the roof with mineral spirits, first. I live near Phoenix, AZ, travel all over the southwest and, last summer, traveled over 10,000 miles to Acadia National Park and back. NO, the GT is NOT garage kept and YES, we get a bit warm around here. No problems.