The other thread got me to thinking if there is a solution that the SF guru’s might know...

I’m replacing my flexible solar panels that died this summer with fixed solar panels on the roof of my RV. In my particular circumstances the manufacturer advised getting 2, eight foot lengths of some sort of metal bar and position it perpendicular to the camper and screw it down on the three raised sections to secure it. I would then mount the panels to these bars.

I ended up getting some 80/20 channel due to it’s strength and weight but I really have a phobia about drilling into the fiberglass roof so I was wondering if there is any adhesive that would allow me to permanently bond aluminum to the fiberglass roof...

They use adhesives to build jets so there must be something out there that is strong enough and not affected by UV etc.

Any suggestions?
Thanks.

The marine industry uses a 3M product called 5200. A lot of boat people hate it, because after it cures, NOTHING will get it off. They also have 4200, about the same, but you can at least cut it off. Any online marine parts place will most likely have both. Defender .com, Hamiltonmarine.com, westmarine.om, etc.

In looking at the 3M 5200 there is some question about its ability to bond to aluminum.. I think I’m going to call 3M and ask them...

UPDATE :

So I decided to call the technical support hotline at 3M (877-666-2277) and the guy said yes it will bond fiberglass to aluminum. Just be sure to give both surfaces a light scuffing and make sure that you don’t intend to remove it as the bond is permanent!

Contact this guy, he's about the best around in RV Solar. His contact information is at the bottom of the Contact Us tab. He should be able to tell you what you need.

Brian Boone Link

There are also epoxies that work well bonding fiberglass and aluminum.

For example, West Systems G/Flex is a tough, flexible epoxy that gets used for applying fiberglass patches over holes in aluminum boats.

I tackled the same project on my RV Motorhome.
I have 6 approx 6" panels on the roof for a total of 2000watts output.
I used 2x4 aluminum bars mounted with the 2" side to the roof (I did this to make up for the difference in the slope of the roof, the inside bars are on the 4" side to the roof.)
I used zinc plated hinges to secure the panels to the bars on the outside so the panels can be tilted and if they need to be taken off all that is needed is to knock the hinge pins out.
I have one bank of 3 panels that are all tied together and lift as 1 unit. These are commercial panels and about 70# each so 210# total.

I also had read about 3m 5200 as a good for ever adhesive. I too did not want to drill holes in my roof.Many Rv'ers and installers use the 3m VHB tape to mount there panels. I was skeptical about a double sided tape, I figured the 5200 would be the answer.
WAS I WRONG!
I mounted cables to each end of my panels so I could lift the panels about 85degrees. I did this so I could work on the roof without having to deal with thin walk ways between panels on the left and right of the roof. I picked this angle because it would help stop the panel banks from blowing over while I was working on the roof.

I have the RV in my backyard. My deck in the yard is raised. I can sit on the deck and see the roof of the RV.
I had the panels raised to the 85degree angle because I'm still working on the install.
This was during the summer and the temps here in Chicago were in the 90's for weeks.
One evening I was sitting on the deck and glanced at the RV. I could NOT see my 3 panel bank that was raised. I went out to the yard and saw the entire 3 panel unit laying on the ground next to the RV.To the credit of the panels all were OK.
The "good for ever, never going to come apart 5200 had catastrophically failed!
To say the least I was emotionally crushed, ALL the work I did was undone.
I had roughed both surfaces with a belt sander with 40 grit belts. I cleaned both surfaces and I used liberal amounts of 5200.I did this last year so the 5200 had over 1 year to cure.

When I went to perform the autopsy as to the failure, I saw that the 5200 bonded well on the fiberglass ( I sanded the gel coat off and brought the fiberglass to the surface to give the 5200 a better bond than just the gel coat on top)
I found the 5200 only attached itself to the aluminum in a few small area. I also saw that heat had softened the 5200. I found this when I went to remove the 5200.An application of heat on the dried 5200 would soften it so I could scrape it off with a chisel, easily.

I was able to raise the entire panel back to the roof. This time I chose 3M 760 adhesive. I hope its bonding to fiberglass and aluminum will work much better.

I will NEVER count on an adhesive only to mount anything of weight and size again! I will in addition to the adhesive through bolt the panels with a series of 1/4" Stainless bolts that go through the aluminum, through the steel ribbed 1 1/2" substructure of the Motorhomes roof and secure with a nut on the inside ( luckily I have over head cabinets all along the inside of the Motorhome so the bolts and nuts will not be seen.)

I have nightmares thinking about what could have happened if those large panels had blown off the roof while driving. The personal injury and damage it could cause to others makes me shudder.

If you have any questions contact me.

5200....we used it in the CG and stuff you glue with it stays glued....forever.