• Have you tried out dark mode?! Scroll to the bottom of any page to find a sun or moon icon to turn dark mode on or off!

diy solar

diy solar

Does it have to be VHB tape?

anunusedusername

New Member
Joined
Feb 21, 2025
Messages
20
Location
Straya
I'm going to stick some lightweight flexible panels directly to the horizontal roof of my RV. It's a flat aluminium surface. From my research it seems like the VHB tape may be overkill for my application. I'd expect they might reach 75 celcius (is that about 170f?) when stationary and be exposed to maybe 150kph (90mph) wind loads. Thanks.
 
if you apply the wrong (weaker) tape, it will be painful to remove it. So better to do the job once with the right tape.
 
is not over-kill if you use little'r pieces!

I do not run VHB tape on every available surface, only where needed to hold it, and removal is certain one day so I try to make it easy on future self.

I use 700-1,500 degree heat gun to remove it with with great difficulty, so 170 degrees should still be fine.

Aluminum, esp RV roofs, is still susceptible to "rotting". Putting the flex panel directly on the roof will eternally trap water which can galvanize or something the aluminum, I say can, not will. When the water is gone the roof will get very hot, and for fiberglass roofs I know it will discolor it, but I havent personally done this on aluminum. Think how you can put some currogated plastic under the panels so air can get under via the plastic flutes. You can do this with EternaBond tape and I have done that on fiberglass roof so there is 100% airflow under, though not a lot of it, but air will never be trapped, nor will water be trapped under a hot panel against a roof.

Do flex panels when needed, for weight or for their low profile, use glass otherwise. IDK how you will remove the VHB tape under a flex panel, you will destroy the panel possibly, but screwing a glass panel to an aluminum frame, then removing the aluminum frame's VHB tape with heat gun after is a lot easier.
Use quality flex panels, not the low cost ones which fail quicker
 
Last edited:
Maybe someone here can help- I am researching VHB tape and there were 2 kinds of 3M tape "5952" and the recommended by William Errol Prowse IV "RP32". I actually used his link on his site. It did bring up some tape which was the "RP32" but wasn't readily easy to find on its own. "5952" kept coming up and well a couple of his links on the website are outdated/not working so I thought maybe this "5952" is the newer version. Asked ChatGTP to compare it advised that the 5952 is the better of the two for mounting brackets on a vehicle roof. Brings me to why I am here. Im stuck on following advice from a human but also want to make sure the link to the amazon store front is displaying the tape he actually recommends and hadn't changed tapes! Man, this is a lot over some tape but its going on an ambulance roof, and I think that would be the ideal mounting method as its perfectly flat and the roof isnt going anywhere.
 
VHB varies. The best VHB cannot be bought in a hardware store because it is made for industrial applications, including holding satellites together. It is specifically designed for extreme situations of wide temperature variations. I used 3M 4950 VHB tape, using mounting brackets. I used only tape to adhere the brackets to my aluminum pitched roof ( common Monaco ) and tape and screws to attack the panels to the brackets. I went with the 4950 because it is the best... it is also butt-clenchingly expensive.

Tape

Plastic brackets
 
I have ordered from Amazon VHB Tape #5952 1” x 15’ four different times. That (and Dicore) is what holds my aluminum solar brackets to my fiberglass roof. Get the VHB primer too. (Also some screws for the first panel in the air stream).

It works very well - be sure and clean very well - put down primer and you are good.

My four corner brackets are 2”x 6” and I have two 1” x 5-1/2” strips of VHB per bracket.

Four years of full-time and none have loosened. Had to take one panel off to reposition (so I could add another and tilt). Had to use a wire saw to cut the tape.

Good Luck with your project!
 
VHB varies. The best VHB cannot be bought in a hardware store because it is made for industrial applications, including holding satellites together. It is specifically designed for extreme situations of wide temperature variations. I used 3M 4950 VHB tape, using mounting brackets. I used only tape to adhere the brackets to my aluminum pitched roof ( common Monaco ) and tape and screws to attack the panels to the brackets. I went with the 4950 because it is the best... it is also butt-clenchingly expensive.

Tape

Plastic brackets
Is this the same stuff? appears to be and decent chunk less $

https://www.amazon.com/dp/B0CFXB78F...?sp_csd=d2lkZ2V0TmFtZT1zcF9ocXBfc2hhcmVk&th=1
 
I have ordered from Amazon VHB Tape #5952 1” x 15’ four different times. That (and Dicore) is what holds my aluminum solar brackets to my fiberglass roof. Get the VHB primer too. (Also some screws for the first panel in the air stream).

It works very well - be sure and clean very well - put down primer and you are good.

My four corner brackets are 2”x 6” and I have two 1” x 5-1/2” strips of VHB per bracket.

Four years of full-time and none have loosened. Had to take one panel off to reposition (so I could add another and tilt). Had to use a wire saw to cut the tape.

Good Luck with your project!
Starting to seem like 3M just likes to add some numbers to practically the same application tapes. lol I do wish there was a more concise gauge of the tapes haha
 
Starting to seem like 3M just likes to add some numbers to practically the same application tapes. lol I do wish there was a more concise gauge of the tapes haha

Ain't that the truth. I've gone down the rabbit hole of trying to find the tape with the most stick and it's frustrating.

I will say that for some circumstances, double sided Eternabond is incredibly strong.
 
I asked Google to compare 5952 to 4950 and this is what it came up with. I don't know how accurate this is, but it sure is a heck of a lot easier asking Google to compare them than tracking down on the 3M site last time I looked.
1745174459657.png

Somebody out there has to have a simple Rosetta Stone type guide to VHB models.

Sometimes when I can't figure out which model of something to use (like tape), the more expensive model is the one I gravitate towards. At least on Amazon, the 4950 is $10 more expensive than the 5952. I don't know if that method works here or not.

4950 (same listing that RvNaut provided)

5952
 
The design guide is a good start but low/medium/high adhesion descriptions don't tell me enough. What I really want are the exact tensile numbers for each model of tape. (Tensile may not be the best metric to gauge to compare the tape models from, but from my layman's perspective, it's what I've got.)

The 3M LSE-060WF has high adhesion to both HSE and LSE. Once again, going on just price ($104 for 2"x5') it's the best. But if you compare the tensile strength of that to the 5952, the 5952 comes out slightly ahead. Of course, I had to dig for the tensile numbers in separate datasheets.

LSE-060WF

5952
 
3M puts out technical documents for the various applications, but they are not particularly helpful for our application
As it was put to me by someone in industrial sales div of 3M.... they will in no way talk about, mention or otherwise discuss using any of their products to attach anything to any RV or other vehicle.... lawyers.
 
@Rocketman @RvNaut @nosys @anunusedusername @Will Prowse

I found this graph here that lists tapes. It's some custom label, sticker they cut shapes in paper in shit including tape and talked about the 3M line. It appears from what they are saying the different number lines 4950, 5952, RP32 etc are practically all the same in adhesion and solvent resistance but varies in thickness and short and long term temperature resistance. I found it helpful/ just peace of mind knowing lol cause it was bugging me the so many different number variations on the VHB tape. I tagged @Will Prowse because I was wondering if there was a reason besides it working he had RP32? It's a bit thinner but also has much lower temp resistance (still high enough I would think). Anyways, that was more than I meant to type. Thanks for the help each of you, thanks for the book Will.

https://coastlabel.com/portfolio-type/3m-vhb/
 
As it was put to me by someone in industrial sales div of 3M.... they will in no way talk about, mention or otherwise discuss using any of their products to attach anything to any RV or other vehicle.... lawyers.
Lol but they will say it can replace rivets, bolts, welds etc thats typical
 
3M puts out technical documents for the various applications, but they are not particularly helpful for our application see https://multimedia.3m.com/mws/media/1400379O/3m-vhb-tape-design-guide.pdf and https://multimedia.3m.com/mws/media/1235572O/uv-primer-technical-data-sheet-canada-english-pdf.pdf
dang, I didnt see this before I posted my link what I found haha.. thank you all im going to stop for now cause yeah. I forgot to refresh my page that was open from last night and bunch of you posted new information. I'll just leave for now. We now have a decentVHB tape thread as non technical I think answers the questions.
 
As it was put to me by someone in industrial sales div of 3M.... they will in no way talk about, mention or otherwise discuss using any of their products to attach anything to any RV or other vehicle.... lawyers.
Perhaps not but they will brag about using it to attach body panels to cargo trailers without bolts or rivets
 
The problem I find with all of the published data is that none of it directly applies to our use case, ie primarily dynamic shear loads at elevated temperatures
 
I forced ChatGTP to pick one explicitly-

Question: "Which 3m vhb tape will hold a solar panel down at high wind speeds and or high speeds? Which one is the stickiest/ would stay connected to an ambulance roof like if it were stuck in the middle of a tornado? Pick one"

Answer:

Alright — if you’re going into battle with a tornado and trusting tape to keep your solar panels down, here’s the absolute beast:

3M VHB 5952
• Type: Heavy-duty acrylic foam tape
• Stickiness level: Ultra-mega (technical term)
• Thickness: 0.045 in (1.1 mm)
• Features:
• Bonds to low surface energy materials (like powder coat, painted metal, plastics)
• Excellent for metal-to-metal bonding (perfect for your aluminum panel frame to ambulance roof)
• Rated for extreme weather, vibration, and shear loads
• Survives -40°F to 200°F+
• People have mounted solar panels, truck panels, spoilers, and wings with this stuff

Why this one?
3M makes a bunch of VHBs, but 5952 is widely trusted for:
• Automotive-grade applications
• Adhering to painted metal and sealed surfaces
• Long-term bonding that doesn’t let go

Cautionary Tornado Note:
VHB 5952 is strong — like strong enough to rip the paint off before the tape lets go — but your mounting surface and prep have to be flawless:
• Clean with isopropyl alcohol (not Windex)
• Avoid dust, grease, or heat while applying
• Apply pressure evenly and let it cure for 72 hours if possible

TL;DR:
Get this one:
→ 3M VHB 5952
It’s your best shot at surviving the next Mad Max storm with panels still stuck to your rig.

I went on to ask why not 4950 or RP32. 4950, the original VHB tape, is also a great contender but is less resilient then 5952. Stiffer, not great on curved surfaces and materials need to be perfectly smooth, it's a bit picky. ChatGTP said a tornado would laugh at RP32.


I appreciate the exchange with everyone here it has been helpful!
 
I am adding another 2 305 watt panels to the roof of my coach (bringing the total to 1110 watts) at the moment and am using 5952 VHB to secure them (Aluminum L brackets to Anodized Aluminum roof after stripping off the old chalky paint (I will be repainting it with Bus Kote thermal insulated paint). I opted to use 5925 (oops typo I used 5952) as it appears to be stronger at elevated temperatures than the other prime options, at least compared to 4950.

The most exposed 305W LG Neon panel at the front of the coach will be held down with almost 100 sq inches of VHB, and the other one due to its location towards the back of the coach will use different brackets and only be held down with about 64 sq inches due to nearby obstacles (roof vents).
 
Last edited:
Remember you are taping the panels to the paint. No matter how will the tape sticks to the paint - If the paint peels, the panels might end up traveling thru the windshield of the person following you.
 
I don't know if you were replying to my message directly above yours or not, but I stripped the paint to the bare anodized Aluminum roof before applying the VHB tape so there is no paint between the VHB and the roof or the brackets

p.s. I would challenge ANYONE to try to pull 2 pieces of Anodized Aluminum apart that are stuck together with 6-12 sq inches (the amount each of my brackets has depending on if side, corner, etc.) of 5952 VHB, after using 3M Adhesive promoter on both surfaces after they have been cleaned with Acetone and IPA. If you can pull just one apart without using pry tools, blades, etc. then we can talk about wind blowing them off the roof.
 
Last edited:
That deal you find on Amazon, eBay, other bargin sites. Probably isn't real 3M tape.
Buy a roll off McMaster. It will cost more, but actually be the real stuff. Once you use that, it is clear the others are fakes.

I've had several rolls of VHB and thought it was decent, but nothing special that I hear about. One time I ended up going through the specs and ordering a roll of the real stuff. OK, now I see the difference. REAL VHB is some pretty impressive stuff. Makes the fakes look like they came from the dollar store closeout bin
 
I agree there are a lot of counterfeit and expired product out there
p.s. I have bought mine from Amazon, but only from the actual 3M storefront
 

diy solar

diy solar
Back
Top