Z-brackets Recommendations for Large Solar Panel Install

[AmyG]

If you can remove the headliner, won't you be able to see where the aluminum frame is? If so, then at least some of your brackets could be attached with through bolts to the frame.

 

[WanderingAlbatross]

I was thinking about the implications of connecting the z-backets through the fiberglass to the aluminum supporting structure. It is a good question because that would provide a significant increase in mounting strength.

It might be unfounded, but one concern might be the flexing of the fiberglass overcab with respect to the aluminum frame. I have not removed the headliner, but if I push down on the outside of the overcab fiberglass it feels like there is about a 1/4" to 3/8" air gap between the fiberglass and the aluminum. These lightweight Sprinter-based Class C motorhomes are not especially rigid. There is a chance that bolting through the fiberglass into the aluminum could lead to the fiberglass fracturing. This concept was what led to the idea of putting aluminum backer plates on the back of the fiberglass overcab because the backer plates would move with the fiberglass as it flexed.

Does this sound like a reason issue to be concerned with? Thanks!

 

[AmyG]

My trailer has an aluminum skin so I really can't comment on the potential for fracturing the fiberglass, but the fact that it flexes that much would make me nervous about mounting panel brackets to it without anything going through to the frame, even with backer plates. I think I'd just take the headliner down if you can and see what things look like. Maybe you could add a spacer between the frame and the fiberglass to keep it from flexing over the frame where your bracket bolts will go? Some rubber bushings or washers that the bolts would go through? Hopefully somebody on the forum has some experience with mounting to this kind of overcab and can share some experience.

 

[HRTKD]

This concept was what led to the idea of putting aluminum backer plates on the back of the fiberglass overcab because the backer plates would move with the fiberglass as it flexed.

Nope, nope, nope. PV panels mounted only into the fiberglass is not going to end well.

 

[WanderingAlbatross]

I'll plan to pull the headliner and look around to see how the aluminum structure is set up. Thanks for the feedback.

 

[eXodus]

Nope, nope, nope. PV panels mounted only into the fiberglass is not going to end well.

the Fiberglass cap of my RV is like 2mm thick - it's very bendy. I wouldn't trust that stuff.

But underneath are 25x50mm 1 inch x 2-3 inch thick aluminum trusses

So I got myself a stud detector and marked those metal components.

I've used stainless steel rivets + to rivet the L and Z brackets to the good structure underneath. Got Large 40x80 Panels mounted.
Didn't come off in my travels during the last 2 years and is not moving whatsoever.

6x Z brackets per panel - 4 oversized roofing screws each - 24 screws per panel into fiberglass to spread the load.
2x L Brackets per panel 2x Stainless Rivets each. - 4 Rivets against uplift (about 1500lbs pull out strength each from aluminum)

Further, I glued the all the brackets to the surface of the roof
I calculated the uplift capacity somewhere in the realm of 10.000lbs so likely the roof structure will be ripped off the RV before the panels fly away.

Which is a distinct possibility... RVs are poorly made in general - once lost the roof of a Class A RV while driving through storm and a funnel cloud decided that I need 30ft convertible.

 

[Marcaroni]

With Unistrut:
1. You choose where the fasteners go
2. It's a heck of a lot easier than Z brackets
3. It's more flexible should you decide to go with larger/smaller panels
4. It's way easier to remove a panel from the room

The one reservation I have with the Unistrut is that it may mess with the drainage pattern on a roof.

I plan to use unistrut and lift the strut every few studs, at least a few inches. either buy "feet" from unistrut or just get some1 by 2 aluminum tubing, cut it a few inches long, and and drill a hole to do the lifting. BTW, where did you find the fitting to use with the unistrut?

 

[HRTKD]

I plan to use unistrut and lift the strut every few studs, at least a few inches. either buy "feet" from unistrut or just get some1 by 2 aluminum tubing, cut it a few inches long, and and drill a hole to do the lifting. BTW, where did you find the fitting to use with the unistrut?

The PV mounting brackets that work with unistrut? I don't have unistrut in my system yet, so I haven't sourced those type of brackets.

 

[12VoltInstalls]

The PV mounting brackets that work with unistrut? I don't have unistrut in my system yet, so I haven't sourced those type of brackets.

I just used the strut nuts and right sized bolts through my solar panel z-brackets

 

[littleharbor2]

Use some 3M 5200 between the brackets and the fiberglass. Be sure to clean the surfaces well. The 5200 alone will hold more than you need. If you plan to remove the panel some day you might not want to use it. It's that strong.

 

[12VoltInstalls]

The 5200 alone will hold more than you need

I’d still bolt it.
I use polyurethane caulking as a structural adhesive very very often but never by itself- always a fastener plus the polyurethane

 

[littleharbor2]

I’d still bolt it.
I use polyurethane caulking as a structural adhesive very very often but never by itself- always a fastener plus the polyurethane

True. I wasn't implying using ONLY 5200 but it sure looks like I did, now that you mention it.