3M VHB Tape

[Wavery]

Originally Posted by Hdlaut

Thanks rickst29. Good input and confirmation regarding thru-bolting and mount spacing.

I bought the brand new Panasonic panel locally for $100 from a guy who gets them from a friend who is a large distributor with leftovers. I helped my son purchase 4.8KW - 12 panels - from the same guy last year for $2k.

I would highly recommend NOT drilling through the TM roof. If you decide to do that, be sure to insert 1" long crush spacers in the roof for the bolts to go through and take all of the force of the compression when tightening the bolts. If you do not use crush spacers (sleeves), The vibration of driving down the road will cause the styrofoam in the roof to crush which will result in having to tighten the nuts farther to keep the panel secure against the roof. Over time, the roof may become severely crushed.

The square tube spacers are an excellent idea for raising the panel off the roof. However, instead of bolting the double tubes together, I would (again) recommend the VHB tape. If you double up those spacers and make them 6" long, you'd end up with 12 sq inches of surface contact with the roof (per leg). that would result in 48sq inches of VHB tape which would result in 3,360# of shear strength and 4,080# of tensile strength. That means that you could lift the entire TrailManor off the ground by the solar panel before that tape would separate.

[Hdlaut]

Originally Posted by Wavery

I would highly recommend NOT drilling through the TM roof. If you decide to do that, be sure to insert 1" long crush spacers in the roof for the bolts to go through and take all of the force of the compression when tightening the bolts. If you do not use crush spacers (sleeves), The vibration of driving down the road will cause the styrofoam in the roof to crush which will result in having to tighten the nuts farther to keep the panel secure against the roof. Over time, the roof may become severely crushed.

The square tube spacers are an excellent idea for raising the panel off the roof. However, instead of bolting the double tubes together, I would (again) recommend the VHB tape. If you double up those spacers and make them 6" long, you'd end up with 12 sq inches of surface contact with the roof (per leg). that would result in 48sq inches of VHB tape which would result in 3,360# of shear strength and 4,080# of tensile strength. That means that you could lift the entire TrailManor off the ground by the solar panel before that tape would separate.

Wow! Food for thought. This may be the best forum on the internet. Thanks!

[jagizzi]

Originally Posted by Wavery

I would highly recommend NOT drilling through the TM roof. If you decide to do that, be sure to insert 1" long crush spacers in the roof for the bolts to go through and take all of the force of the compression when tightening the bolts. If you do not use crush spacers (sleeves), The vibration of driving down the road will cause the styrofoam in the roof to crush which will result in having to tighten the nuts farther to keep the panel secure against the roof. Over time, the roof may become severely crushed.

The square tube spacers are an excellent idea for raising the panel off the roof. However, instead of bolting the double tubes together, I would (again) recommend the VHB tape. If you double up those spacers and make them 6" long, you'd end up with 12 sq inches of surface contact with the roof (per leg). that would result in 48sq inches of VHB tape which would result in 3,360# of shear strength and 4,080# of tensile strength. That means that you could lift the entire TrailManor off the ground by the solar panel before that tape would separate.

I agree with you about the bolts crushing the roof if they were the principal means of attachment. They are merely back up to the UV4000 Adhesive Sealant. If the sealant fails I won't have the panel go sailing away on the freeway, and I will get a failure indication when it rains as the leak will end up on the bed.

In regards to doubling up the square tubes to increase surface area I am in complete agreement. So much so that if you look at the photo closely you'll notice just that. I doubled up to increase the surface area ;-) for the adhesive.

[jagizzi]

I have a lot of faith in VHB tape but I also understand that things fail, over time, with weather, sun and heat exposure. I chose an adhesive with a mechanical backup based on those thoughts and some personal experience.

I have always had rain guards on each of my three Ford F-150's. Ford parts with preinstalled VHB tape on the guards. Each truck had 4 guards for a total of 12 over the years. One of them came off of the truck going down the highway. The tape was on the truck but the guard had come away from the tape and left the vehicle. Poor surface prep on the part of a factory I am sure.

My techs used VHB tape for simple window handle installs in my service department for Yachts and boats. Almost always we had no problems, customers were happy and we never saw them again once the handles were reinstalled but...there were several times that the handles came away from the tape and we had to do the job over. Poor install conditions most certainly in one case and bad surface prep in another that i can remember.

A factory install failure and several failures on a low stress part convinced me that I would prefer to have a mechanical fastener as a safety backup. My choice, based on my experience. Was something done incorrectly with regards to surface prep or install conditions (temp, humidity etc) with the VHB tape, most certainly. This makes any spec for bonding strength invalid.

This was my thought process for my install.

[jagizzi]

And I wholeheartedly agree that this is one of the best forums on the web. i would not have been able to get through my 2005 2720 refit without it, and those that participate in it. Thanks to all of you for your thoughts, discussions and comments. I am still learning tons ;-)

[Wavery]

Originally Posted by jagizzi

I agree with you about the bolts crushing the roof if they were the principal means of attachment. They are merely back up to the UV4000 Adhesive Sealant. If the sealant fails I won't have the panel go sailing away on the freeway, and I will get a failure indication when it rains as the leak will end up on the bed.

In regards to doubling up the square tubes to increase surface area I am in complete agreement. So much so that if you look at the photo closely you'll notice just that. I doubled up to increase the surface area ;-) for the adhesive.

My main concern about the through bolting is that your solar panel is fairly heavy and mounted behind the trailer axle. When the TrailManor goes down the road, everything behind the axle has upward AND downward thrust, like a whip. The pressure of the downward thrust will be lessened by the 3M4200 sealant that you used. However, the upward thrust will pull the bolt and backing plate up against the roof panel. The combination of the 2 will most certainly cause the styrofoam between the inner and outer skin to compress if you do not have a crush sleeve in there.