drilling holes in bigfoot roof for solar panels

[wallnut1234]

my concern is if I go with srews AND VHB tape, since I cant put butyl tape between the mounts and the roof (since the VHB tape is there), will that indroduce a leak risk. If I go that route I would put lap sealant around and on top of each mount, just not sure if thats enough

[stevebaz]

if you are going to use VHB call 3M and get the right one. make sure the areas of bond are clean and no wax or other coatings are there before bonding. follow the 3m data sheets on the product. if air can get under the panels when installed I would use fasteners. I would not use rivnuts, their failure rate is quite high, once the bolts get corrosion on them. fiberglass will not hold them from spinning once a little corrosion sets in. 3m 5200 is great stuff but 3m 4200 is less permanent.

[ZachO]

I'm no expert, but I think VHB and lap sealant would be enough. At least I'd be comfortable with it.

[wallnut1234]

Originally Posted by ZachO

I'm no expert, but I think VHB and lap sealant would be enough. At least I'd be comfortable with it.

yeah I might do that, theres so many different opinions on whether rivets/rivnuts/well nuts would work and not many people seem to have actually done it, VHB tape on the other has been "tested" by more people with a small fraction of panels ripping off possiblly because they were installed on the clear coat of the trailer... My initial idea was to minimize the "ripping off" risk by combining both methods but... not sure I want to be the one testing out new ways of securing a solar panel to a roof...


decisions, decisions, decisions

[ZachO]

Both Eternabond, Dicor and probably a lot of other options also do more than seal. They provide quite a bit more holding power and surface area. If you've ever tried to scrape either of them off your roof when resealing vents, you know what I mean.

I don't know. For me, it's not worth expanding nuts and all that. I'll either stick with VHB + Eternabond or go fully through the roof with bolts.

[Mooncusser]

Vhb tape has a tensile strength of something like 70-80 lbs per inch. I have 8 mounting points over an inch long each bracket. The panel weighs maybe 60 lbs and it's a big bastard just about as big as they get. Like ZachO mentioned along with some sikaflex or proflex around the edges the keep the water off the tape, properly applied on a clean alcohol wiped roof, your panel isn't going anywhere.

If you were worried about it you could get a bike lock cable while towing and traveling and go thru the aluminum edge of the solar panel and attach to a strong mount point on your trailer like the bolts holding your awning or something similar , just in case it did come off, which it won't, for peace of mind. I know mine won't

Or just bolt the thing down and put holes into your roof and be prepared to maintain it so it doesn't leak.

Good luck

[redbarron55]

It's not the weight of the panels that matters, it is the wind load if it gets under with a gust or a blast from a passing truck.
Remember the basic gust loading would be your 65 mph PLUS the 65 mph (or higher) gust from that passing truck for a gust load of 130 mph or in the case of a large flat nosed truck considerable higher "shock" wave hitting it.
Bolts or screws through the fiberglass with washers inside for me.

[wallnut1234]

Originally Posted by redbarron55

It's not the weight of the panels that matters, it is the wind load if it gets under with a gust or a blast from a passing truck.
Remember the basic gust loading would be your 65 mph PLUS the 65 mph (or higher) gust from that passing truck for a gust load of 130 mph or in the case of a large flat nosed truck considerable higher "shock" wave hitting it.
Bolts or screws through the fiberglass with washers inside for me.

yeah, I'd feel more comfortable with that. It's not really doable with a bigfoot though since the roof is thicker than with the scamp (I believe)

[redbarron55]

Originally Posted by wallnut1234

yeah, I'd feel more comfortable with that. It's not really doable with a bigfoot though since the roof is thicker than with the scamp (I believe)

I assume that the Biigfoot is a double shell with insulation between them. This is why I would consider using the largest rivnut to get the most engagement possible around the circumference of the hole drilled. The longer grip length would build a larger bulge flattened out under the glass.
I might consider dipping the rivnut in some epoxy glue before setting it to bond it as firmly as possible to the glass. If the glue were to fill the threaded area you can always run a tap through it. Clean the rivnut puller with acetone after using it this way.
Make sure you use a drill that cuts the cleanest hole possible as you don't want to shred the fibers any more than possible. The epoxy would tend to stick all of this to the nut.
Well nuts might be a good choice, but I think stainless would be better.

[ZachO]

Originally Posted by wallnut1234

yeah, I'd feel more comfortable with that. It's not really doable with a bigfoot though since the roof is thicker than with the scamp (I believe)

Pretty sure they make bolts and screws of all lengths

[Nicolas]

There is an alternative to tape and drilling holes: install your mounting bolts to the roof. Simply locate where the bolts need to go; decide how large the mounts will be; rough the surface area to accommodate the bolt and mount; mix up a batch of fibreglass resin and hardener and paint it to the roughed up area; mix in some bonding agent and apply it to the area; press your mounting bolt into the bonding agent; apply more bonding agent to the bolt; bond a piece of fibreglass tape into the bonding agent for extra security; allow to dry; sand and clean with lacquer thinner; mix more resin and hardener plus filler to form the mount’s shape; allow to dry; sand and shape “et voila” you have a mount that does not got into your shell and won’t peel off.

[Craig Alan]

VHB 5952 holding Z-brackets is working for us. I used silicone to protect the tape around the edges and holes in the bracket. Z-brackets are angled using hard rubber toilet shims between bracket and panel to match the curve of the Casita.

The VHB holds 90 lb/sq in under lab conditions. With 4 sq in per each of four brackets, that's about 1400 lb the tape should support. With a safety factor of 2, the tape should easily support a 700 lb force. I can't imagine that being delivered by anything short of a tornado or turning the marshmallow on her back.

I installed per 3M directions, cleaning all surfaces fastidiously and applying as much pressure as I could, given the nature of a roof installation.

[Fran L]

FYI....We own a 2008 Escape 5.0 and in 2013 we had Escape install a rigid solar panel. At that time Escape was using epoxy to secure the panel frame to the roof. Our panel blew off during a strong crosswind storm. It tore part of the fiberglass off...there may have been some issue with the initial install but there were a couple other cases like ours so Escape quickly sent out retrofit kits to drill through and secure the panels that way. They now build mounts into the fiberglass during fabrication to secure the panels.

[Anthony B]

I'm about to do this too my bigfoot. The problem it Bigfoots have 1" of foam under the roof. So if you want to throughbolt you have to tear your roof apart. Not gonna happen. You can use rivnuts or well nuts of you can do it marine style. Oversize hole. Hollow out the foam behind it and then fill with epoxy (good epoxy) and then then drill a hole in that and screw into it with your stainless metal screw. Its effectively a big epoxy nut that is sealed. you want to use an adhesive sealant between the roof and your braket as well, cover the screw head.

I'm not going to be that fussy. I'm going to drill a hole at the size of the minor diameter of the #14 stainless metal screw (two per bracket). and then hollow out the foam a little bit. I'm then going to fill it with epoxy and apply sealant and wet screw it. The epoxy will solidify around the screw which will be held tight by the thin glass shell as it sets and it will provide extra holding power. I'm going to use Lexel which is similar to "through the roof".

potential issue is that there is a gap between the foam and the roof which allows the epoxy to run laterally. I'm going to make the hole in the foam shallow (about 1/4") and hope that the metal screws bite into the foam enough to suck it up to the skin and make the epoxy bond to the back side.

By the way, I just redid a roof vent on the bigfoot and they didn't even remove the gelcoat from the edge of the holes and they all had spider web cracks same with the sloppy cut out. They were not too concerned about just slapping it up there. We DIYs are way more fussy than professional installers.

[JPr]

Hey there!

I just installed 2 x 100W rigid panel on my trillium (about 6 months ago).

I used both 3M 4950 VHB and rivets. Essentially VHB tape between the brackets and the roof and then riveted through the VHB tape and brackets.

Finally, used lap sealant over it all.

Ive been through hail, heavy down pours, high winds, 120km/h plus on the highways and nothing has come off yet nor leaked.

[Anthony P.]

Panel Bond is a super industrial adhesive that auto body shops and auto manufacturers use to affix body panels instead of welding. Porsche and other exotics are assembled with proprietary panel bond. I would fabricate an outer mounting frame with flanges on the bottom where it will be attached to the roof. Panel pond the frame, then mount your solar panels in the frame. Solar panels would be removable for maintenance.

[wallnut1234]

Originally Posted by JPr

Hey there!

I just installed 2 x 100W rigid panel on my trillium (about 6 months ago).

I used both 3M 4950 VHB and rivets. Essentially VHB tape between the brackets and the roof and then riveted through the VHB tape and brackets.

Finally, used lap sealant over it all.

Ive been through hail, heavy down pours, high winds, 120km/h plus on the highways and nothing has come off yet nor leaked.

I like that solutoin a lot, did you use the rivets designed for plastic, I think there called bulb rivets?

[ZachO]

Originally Posted by Anthony B

I'm about to do this too my bigfoot. The problem it Bigfoots have 1" of foam under the roof. So if you want to throughbolt you have to tear your roof apart. Not gonna happen.

Is this what everyone is talking about with not being able to "throughbolt" a Bigfoot roof?

I know someone will correct me if I'm wrong, but all those with single layer shells who put a bolt through their roof have the end of the bolt on their ceiling. It goes all the way through. You can touch the head of it when you're in the trailer. Why is it that once you have a double-hull with insulation, you can't still go all through way through the ceiling? The concept remains the same, in my mind. You just have more layers to go through. What am I missing?

Fran's example is a perfect one. We can talk theoretical forces and holding power as much as we want. The truth is that panels installed with VHB-only have blown off, the failure wasn't the tape but the fiberglass, and not only during natural disasters. That doesn't mean it will happen to you or me. But it can and does happen.

[giro53]

My 140w panels were attached to l brackets and screwed in with calking arround and over screws butle tape under. 4 yrs later, never any problem

[JPr]

I didn't, but that's a good idea.

When using metal rivets you have to be careful to stop apply pressure to the rivet gun just before the rivet breaks. Other wise it might pull though the fiberglass.