VHB or Eternabond

[AJMike]

I have watched some videos which discussed attaching flexible solar panels using tape, three of them being the RVing with Tito, I'm Not Lost, I'm RVing and RVHobo. My Fuse's roof is fiberglass and the RVHobo video indicated the fiberglass was very good for taping.

I know that using tape to attach solar panels, even flexible ones, is a bit of a hot button issue for some people and I do not want to stir the pot, so to speak, but I did want to ask what the differences were between VHB and Eternabond tape. Are they equivalent? Or is one better than the other? Can either be removed after application? Or are they both "eternal" once applied?

[BobC]

They are completely different. VHB is a double-sided adhesive tape made by 3m that can be used to adhere your solar panel mounts to your roof in lieu of screws.

Eternabond tape is used to seal roof penetrations so they don't leak. If you were to adhere your solar panel mounts to your roof with screws, you would apply Eternabond over the top of the screws and mounting flange so it doesn't leak. In addition to the Eternabond, you'd want to use an appropriate sealant between the mount and the roof, and in the screw holes. Eternabond itself has no appreciable adhesive strength beyond what it needs to stick to the surface to which it's applied.

If you use VHB alone to mount your panels, there's no roof penetration, hence no need for Eternabond. If you use VHB in addition to screws, you'd need to use Eternabond as described above.

VHB + screws is a "belt-and-suspenders" approach to mounting solar panels.

Neither is eternal and both can be removed. Eternabond with a combination of a heat gun, a hard plastic scraper, mineral spirits and Acetone for final clean-up. It's a messy process but once you get the hang of it can go pretty quickly.

Since VHB is going to be hidden between the mount and the roof, I'd first use a steel guitar string or similar thin strong wire to "saw" it loose. Using a thin knife or hacksaw blade would also work but might damage your roof. Once the mount is removed you can remove the remaining residue as described in this link:

https://www.hunker.com/13415419/how-...ove-a-vhb-tape

(It's possible that the "sawing" step can be eliminated if the WD-40 or Goo Gone will seep in far enough to dissolve the bond.)

[AJMike]

Originally Posted by BobC

They are completely different. VHB is a double-sided adhesive tape made by 3m that can be used to adhere your solar panel mounts to your roof in lieu of screws.

Eternabond tape is used to seal roof penetrations so they don't leak. If you were to adhere your solar panel mounts to your roof with screws, you would apply Eternabond over the top of the screws and mounting flange so it doesn't leak. In addition to the Eternabond, you'd want to use an appropriate sealant between the mount and the roof, and in the screw holes. Eternabond itself has no appreciable adhesive strength beyond what it needs to stick to the surface to which it's applied.

If you use VHB alone to mount your panels, there's no roof penetration, hence no need for Eternabond. If you use VHB in addition to screws, you'd need to use Eternabond as described above.

VHB + screws is a "belt-and-suspenders" approach to mounting solar panels.

OK. Thanks.

I have looked for VHB tape on the internet (checked with Amazon first) and ran into what seems to be a serious issue, at least for me. I felt I needed at least 2" wide tape to make sure there was enough to secure both the side of the solar panel and the roof, but the only wide VHB tape came in very long rolls and were priced at over $200 for a single roll. I only need about 10 feet of the stuff so I was wondering if there was anyplace you knew about that sold smaller lengths, but in at least 2 inch widths. Google was not much help to me.

FWIW the online videos that I saw on "no drill" solar panel installation all used Eternabond, not VHB tape, and that seems surprising to me in light of what you posted. I am sure you are right, but am puzzled as to why the RV with Tito and I'm Not Lost videos would use Eternabond rather than VHB.

[WinnieView]

Originally Posted by AJMike

OK. Thanks.

I have looked for VHB tape on the internet (checked with Amazon first) and ran into what seems to be a serious issue, at least for me. I felt I needed at least 2" wide tape to make sure there was enough to secure both the side of the solar panel and the roof, but the only wide VHB tape came in very long rolls and were priced at over $200 for a single roll. I only need about 10 feet of the stuff so I was wondering if there was anyplace you knew about that sold smaller lengths, but in at least 2 inch widths. Google was not much help to me.

We just ordered the roll of 1" x 5 yd VHB tape and will use two strips as needed under each mounting bracket.

[AJMike]

I must have been up too late last night because I just re-read your post and it has answered most of my questions. If I wanted to use VHB tape for the solar panels the tape would have to sit between the roof and the solar panel since it is two sided. The Eternabond is single sided tape and was used to tape the panels on top of the roof directly.

Simple. Thanks again.

[AJMike]

Originally Posted by WinnieView

We just ordered the roll of 1" x 5 yd VHB tape and will use two strips as needed under each mounting bracket.

Yes. I was thinking about this all wrong. The VHB tape would be used to hold the brackets but if I wanted to tape the solar panels directly to the roof I guess I would use the Eternabond.

[BobC]

Originally Posted by AJMike

FWIW the online videos that I saw on "no drill" solar panel installation all used Eternabond, not VHB tape, and that seems surprising to me in light of what you posted. I am sure you are right, but am puzzled as to why the RV with Tito and I'm Not Lost videos would use Eternabond rather than VHB.

I took a look at the RV with Tito page (https://rvwithtito.com/articles/how-...el-no-drilling) and he's using Eternabond to mount flexible panels, which is altogether different from mounting traditional solar panels and mounts. There would be no upward force exerted on the flexible panel since it's tight against the roof, plus there are more square inches of tape adhering it than you'd have on a traditional mount. Without a link, I can't tell for sure what I'm Not Lost video you've looked at but if you post the link, I'll check it out.

[AJMike]

Originally Posted by BobC

if you post the link, I'll check it out.

https://www.youtube.com/watch?v=mFK-iIHLx94

[BobC]

Again, flexible panels, a completely different animal. If that's what you're installing, Eternabond is probably OK. If I was doing it, just to be safe, I'd use a few pieces of VHB at the corners, and maybe in the middle of each edge and then put Eternabond around the edges.

Traditional solar panels are going to have some form of aluminum mounting feet that will hold it above the roof, four to six per panel and there's no way that Eternabond is going to hold them down.

IMHO it's not a good idea to secure traditional rigid panels directly to the roof. First of all, your roof is curved so there's not going to be a solid bond all the way around. Second, the wiring comes from beneath the panel, and third, you want to be able easily remove the panel if necessary. In any case if you were to want to mount it directly, since it's 1 1/2" - 2" thick, you're going to want to use VHB, not Eternabond.

[AJMike]

Originally Posted by BobC

If I was doing it, just to be safe, I'd use a few pieces of VHB at the corners, and maybe in the middle of each edge and then put Eternabond around the edges.

Yes. That sounds like a really good idea.

[rarebear.nm]

Many people like flex solar panels for various reasons and that's great. Just a word here- carefully checkout the warranty for whatever flex panel you are looking at. Some are much better than others. Also review the real life times for these panels and how you might replace them if required. Not trying to steer you in any direction, just have your eyes open up front.

Have fun and be safe...

[AJMike]

Originally Posted by rarebear.nm

Many people like flex solar panels for various reasons and that's great. Just a word here- carefully checkout the warranty for whatever flex panel you are looking at. Some are much better than others. Also review the real life times for these panels and how you might replace them if required. Not trying to steer you in any direction, just have your eyes open up front.

Those are great suggestions. As for the reviews, I read them before I bought the panel and they were all very good. Doesn't mean that people still feel that way after a year or two but I did check. I did check the warranty and it says "5 year power, 2 year product" whatever that means. I don't see how you can separate product from power.

One more comment. I realized when I bought this panel that I was taking a chance. I am investing little in the purchase - the panel (about $200), an adapter to convert from MC4 to SAE ($20) and the mounting material (VHB tape and silicon sealant. All together perhaps $260. If any of these panels fail I will remove them and replace them with rigid panels, and I will then have some idea what I am doing. At least I hope I will ...

[BobC]

You'll probably be OK, just don't walk on them.

[rarebear.nm]

Looks like your investment is not very great and is worth the chance as you say. Either way it will prove a learning experience. But life is like that.

Very short note on warranties:

A power warranty basically says that after some time period the panel will still produce some percentage of it's original rated output. Common number for fixed panels is like 80% after 20-25 years. Varies all over the market place.

An equipment warranty more or less covers product and workmanship for a stated period. Again great variations are seen.

IMO Sunpower has some of the better warranties. But there are so many players and its always changing. There are some combination warranties and other what not and frequently lots of fine print.
Here's one link that might help some:

Solar panel warranty vs. performance guarantee: What’s the difference?

Hey, just get started and see where it goes for you. There's is no one right or best solution for everyone.