3M VHB Tape

[Mack1]

Gents. Which tape are you using to attach your solar panels? Is it 4950?? Thanks. Mark

[Cally]

Yes, 4950. Bought on Amazon.

[Mack1]

Originally Posted by Cally

Yes, 4950. Bought on Amazon.

Thanks!👍

[Hein]

We recommend 3M VHB 4611 which has a higher temperature range than 4950



All the best,
Hein
DIYvan
541 490 5098

[lsbrodsky]

AM Solar provided 4950 which implies that it has worked well for their installations and sales. That is what is on my roof.
Larry

[strangepod]

So let me get this straight, there is no issues with attaching solar panels to the roof using the VHB tape? Even under high winds etc? The reason I ask is I am about to add two 70W panels my rig and this would be a better way to do it vs the alt.


John

[lsbrodsky]

Look at the AM Solar recommended method, also used by Lew, with no reported "fly-offs". You need to clean the surface before applying the tape, then you protect the tape by applying Sikaflex on and around the mount. It has been fine for me.
Larry

[DotsDad]

3M’s VHB family of products are pretty amazing. When we had our big diesel pusher, we used VHB to attach solar panels, antennas, etc. 85 mph didn’t faze it. As others have said, it’s important to choose the right VHB product. Generally speaking, the things to consider are the VHB thickness, adhesive type and temperature range. 3M publishes a great selection guide that is attached.

Two VHB tapes are mentioned above. VHB 4950 and 4611 have a general-purpose adhesive suitable for aluminum. Both have a thickness of 1.1 mil. All VHB tapes perform well to 200 deg F.

My personal preference is VHB 4991. Again, a general-purpose adhesive suitable for aluminum, but with a thickness of 2.3 mil. In the attached 3m VHB information, 3m mentions that, “the necessary thickness of tape depends on the rigidity of the substrates and their flatness or irregularity. While the 3M VHB Tapes will conform to a certain amount of irregularity, they will not flow to fill gaps between materials.” They go on to say, “large parts where a higher degree of expansion and contraction is expected might need thicker tapes.”

Because the roof temperatures of our rigs can vary from sub-zero to well over 100 deg F, we need to use a product that works well in a high-expansion environment. Also, although aluminum is fairly rigid, the skins of our trailers are not always perfectly flat. Thicker foam substrates such as that in VHB 4991 will conform to and fill small gaps that could be present. 3m says, “consider the use of conformable or very conformable foam types to increase the contact area and reliability on rigid substrates.” This can result in greater adhesion and shear strength.

The size of the solar panel brackets and amount of tape used is important. Because the wind load will generally be spread across the bonded areas, a larger bracket fully covered with VHB trumps one with a smaller footprint.

It’s important to clean the 2 surfaces well before applying. 3m makes an adhesion promoter product available on Amazon.

Application temperature and cure times matter too. Ideal application temperature is 70-100 deg F. Minimum temps vary by product family and are listed in attachment. At room temperature approximately 50% of ultimate bond strength will be achieved after 20 minutes, 90% after 24 hours and 100% after 72 hours.


Mark

[GMFL]

Originally Posted by strangepod

So let me get this straight, there is no issues with attaching solar panels to the roof using the VHB tape? Even under high winds etc? The reason I ask is I am about to add two 70W panels my rig and this would be a better way to do it vs the alt.


John

Correct,
I’ve used it for years. With very simple and proper prep VHB will hold panels to the roof without issue.
The combination of VHB 4950 or 4941 and then cover with Sikaflex 221 or Dicor works GREAT

[Mollysdad]

3M sells VHB tape in rolls that are 36 yards long!
Okay for builders, but a lifetime supply for a handyman.
The stuff you buy on Amazon, like I did, are rewound from long rolls to small rolls, 15'. It effects the strength.
My first attempt to use it failed in 24 hours.
Amazon reviews say I'm not alone.

[Hittenstiehl]

Mollysdad would you be able to tell us which one you used and what kind of application you were using it on.

[Mollysdad]

Originally Posted by Hittenstiehl

Mollysdad would you be able to tell us which one you used and what kind of application you were using it on.

Okay.
Here's what I ordered, more because of width and length rather than number. 3M Scotch 5952 VHB Tape: 1 in. x 15 ft.
I got it to secure my microwave to a couple brackets so it doesn't move so much underway. Before I did that, I tried to attach a shower bracket to tile at home. It fell.
Currently, I'm using it to attach a 'Level Mate Pro' transmitter to a wood surface just inside the door before I drill any holes. So far, so good, but that only weighs an ounce or two.

[Hittenstiehl]

Thx Mollysdad, appreciate it.

[nvestysly]

I've used 3M VHB tapes in a number of engineering applications in the electronics industry. Those products experienced temperature from -40C to +100C but the forces involved were relatively small.

I too am surprised VHB works to secure solar panels to the roof of an RV. Lewster and others certainly have real-world experience and I will use the recommended VHB if/when the times comes that we install solar panels.

Regarding the failure that Mollysdad experienced. There are quite a few variables when using "double-sided" tape, even the super-duper 3M VHB. The most obvious is clean surfaces. Another obvious item is the amount of surface area for the joint. I don't know the force/unit area specs for VHB but additional surface area will certainly provide more holding power. Less obvious is applying pressure to allow the tape to cure. The longer the pressure can be applied the better. A few moments is okay, a few minutes is better, a clamp or the weight of the device (i.e. solar panel) to hold the joint in position is the best. In addition, 3M indicates the tape requires 72 hours for full cure. Molysdad may have experienced a failure if the item was placed in service too quickly. The least obvious of all the selection criteria is surface energy of the materials. Molysdad used 5952 which is intended for low surface energy materials. Not knowing all the materials involved in attempting to secure the microwave, or the shower head, etc. we don't know if 5952 was the right choice or not.

[Arash]

Does anyone have experience with 'removing' VHB tapes? I am trying to figure out what tape to use to install my flexible, lightweight solar panels, but I am also trying to be cognizant about removing them in case I need to replace a panel.

Also, my panels will most span across both the white coated part of the roof as well a bit of aluminum part. Would that be of any concern (taping to both surfaces)?

[goldenchase]

Originally Posted by Arash

Does anyone have experience with 'removing' VHB tapes?

Yes I do. If you apply VHB tape right it is really hard to get off. Applying it right is all about surface preparation. Having said that I have always been able to get it off without hurting the surface but sometimes it is an heroic effort.

[AKNate]

Originally Posted by Arash

Does anyone have experience with 'removing' VHB tapes? I am trying to figure out what tape to use to install my flexible, lightweight solar panels, but I am also trying to be cognizant about removing them in case I need to replace a panel.

Also, my panels will most span across both the white coated part of the roof as well a bit of aluminum part. Would that be of any concern (taping to both surfaces)?

I installed my flex panels with 3M Dual Lock SJ3870. It’s essentially VHB on one side and a super strong “Velcro” on the other. If I ever need to replace a panel I can just peel off the old panel, stick some new strips of Dual Lock to the new panel and stick it back on the roof. I wouldn’t want to ever try to remove VHB. It has a very high bond.

[Tater]

I remove the VHB with double stranded dental floss.