Best way to fasten a solar panel to caravan roof?

mbikeman1, Oct 21, 4:27pm
Don’t want it to leak and don’t want it to fly off while travelling.Tek screw or bolt or pop rivet nuts?

gpg58, Oct 21, 4:39pm
I am going to fit another large one to my bus(410w mono perc, half cell version -2817962636), and will use a glue system, but likely may add some sealed rivet's as well, as not sure i trust gluing only(how well is the paint i am gluing to stuck on, and removing lining to bolt is not an easy option)-probally should clean paint off first, truth be known.
https://youtu.be/jDaejsBxeFg?t=6

tony9, Oct 21, 4:40pm
Silicone Sealer/Adhesive worked for me. Make sure you use one that is also adhesive and clean the roof properly.

tygertung, Oct 21, 4:48pm
If you can remove the lining inside, bolting it would be by far the most secure as the roof of a caravan is likely to be sheet aluminium. Just ensure you seal with silicone.

chalkie51, Oct 21, 5:42pm
Bostick Simson adhesive.

budgel, Oct 21, 5:47pm
I think bolting a bracket to the roof with well sealed rivnuts, but make the panels removeable.

cattleshed, Oct 21, 6:41pm
A roof rack concept with the mounting on the vertical side panels. I would not drill into the roof.

kingfisher21, Oct 21, 7:28pm
Sikaflex

morrisman1, Oct 21, 7:38pm
bostik 70-03 is good, or 70-08 is windscreen glue if you need it to be thicker. Just don't expect it to come off easily, Id only glue it within reach of a craft knife just in case you need to remove one day. I use it for heaps on the race car and its very good stuff. Its nice and flexible but sticks well and is weatherproof. Ideal really for what you are doing.

mbikeman1, Oct 21, 8:15pm
I really like the roofrack idea but two thing put me off,Security as someone could probably undo without having to climb up and then there’s the fact I couldn’t use my awning.Kinda gutted about that though as it would have been the easy option.So it sounds like a really good sealant/glue is needed and possibly rivnuts to seal the deal.Will look into sourcing rivnuts first and then sort out sealants etc.Thanks guys👍

frank1, Oct 22, 9:59pm
What are rivnuts? --rivets maybe?

ml6989, Oct 22, 10:03pm
I bolted 3 50 X 25 aluminium box sections to the panel and then used windscreen urethane to fix it to the roof. Spent the first 1000km of travel watching in my rear view mirror. No problems and it is still there after 20000km of travel. I inspect annually and all is still well. Urethane holds windscreens in vehicles and forms part of the vehicle structure so has good strength (and adhesive) qualities.

gpg58, Oct 22, 10:04pm
https://www.youtube.com/watch?v=P_uu_ba6qAM

Some do not use pin, and just rely on a serrated surface to grip (which often doesn't imo)

tmenz, Oct 22, 10:05pm
Rivnuts are threaded aluminium flanged inserts that are squeezed/deformed into holes, much like pop rivets, using a dedicated tool.

intrade, Oct 23, 1:14am
A caravan is made of tin foil like substance drilling holes is the worst idea . The best is to use a sealent a airbus a380 is mostly glued with sikaflex like substances I would use wurth or automotive panel bond as new cars are also glued more and more riveting to tinfoil you get leaks and it won't hold . Basically a sure way to ruin the caravan .What you do want is a good panel and the right place to fit it for ever as that what them adhesives are designed for.

gpg58, Oct 23, 12:44pm
Bought a cartridge of "sikaflex 11 fc" at bunnings to do mine, just a note if buying it there, they keep the nozzles under the counter, unlike the smaller diameter ones for other types of cartridges, which are freely available in a bin etc.(supposedly due to often being stolen), but gave me 2 without me asking for the extra one.
https://nzl.sika.com/content/dam/dms/nz01/r/sikaflex_-11_fc.pdf

mbikeman1, Oct 24, 11:08am
Hanks again for the input guys,I went into mitre10but there was to many options for sika but now I’ve been given an exact product I can head back in and grab it.As mentioned above should I take off the paint in the area I’m going to glue to?Im not sure if I should trust the paint not to flake off

gpg58, Oct 24, 11:29am
I intend to mark out mounting feet on roof, and clean off paint under them only, which will also roughen the metal for better sticking(mines steel i think, so not decided if i will primer paint first, with etch primer or dry galv?, as will then be sure it is well stuck) Still inclined to use some sealed rivets as well though, as mine is a big panel, which may get a lot of wind under it creating lift. Also now debatting if that sikaflex is right one, as only rated to 70deg, and thinking now that panel and any alloy brackets may get above that? However my supplied mounts are plastic, so perhaps unlikely to get as hot as panel.

gpg58, Oct 24, 11:51am
A search for Sika flex high-temperature silicone sealant found the product sikaflex 221, which is rated at 90 degrees or up to 120 degrees for a day/140deg for an hour, so I think I will now go and get one of those to use instead

gammelvind, Oct 24, 12:04pm
I sell Dekasyl MS5 for this very purpose. High green strength, surface tolerant and UV resistant. It’s a single pack cartridge easy to apply, strong as, and reasonable price.
A caravan place tried to pull a satellite dish off the roof of a caravan. Glue was stronger than the bonding of the alloy to the liner on the van. Has to be cut off.

gammelvind, Oct 24, 12:05pm
Make sure you paint the 221 as it has no UV resistance.

gpg58, Oct 24, 12:56pm
Thanks, Just in Bunnings now and looking at the 291 Marine, which on the data sheet says it will tolerate 160 degrees for up to 4 hours so now going to grab that in the white colour.

https://www.google.com/url?sa=t&source=web&rct=j&url=https://nzl.sika.com/content/dam/dms/nz01/y/sikaflex_-291.pdf&ved=2ahUKEwic0IzS9MvsAhU9IbcAHbXsC48QFjAAegQIIBAC&usg=AOvVaw2ZE7VWMfKhbfT4HiBqnGX_

gpg58, Nov 2, 3:02pm
Just found this chart online, for sika marine products, so 291, or 292 for even more strength should be fine.
But for plastic windows, a very high uv rated product like 295 is recommended, and 296 for glass.

https://trademe.tmcdn.co.nz/photoserver/full/1423340651.jpg https://www.bluemoment.com/downloads/sikaflexmarinehandbook.pdf