Mounting solar panels to curved fibreglass roof


New member
Hi all,

After putting off this horror show for ages I'm attempting to mount solar panels on the roof of a Sprinter saddled with a curved fibreglass roof.
As you can see from the attached images said curvature is playing havoc with my hopes of a smooth install.
Due to the size of the panels, they must be mounted with these alu strips along the short ends.

The fibre is about 3mm thick and periodically braced. As you can see from the last image, at its most extreme the gap is 35mm.

My original plan was to go mastic only but there's no way that space is getting filled with bond - any thoughts on best plan of attack and how to make it is as pretty as possible?

Solid wooden spacers? Would 3 screws through into wooden blocks do the job (a spacer at each end and one through the middle?

Alternatively - should I just suck it up and get some roof bars fabricated...


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2004 T1N Westfalia
Use semiflexible solar panels and 3M Dual Lock ( Plastic mushroom velcro with 3M adhesive).

Alternative is polycarbonate sheet backing (pliable).and bolts.

See subforum for Airstream Westfalia with fiberglass top.

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2008 NCV3 170ext
Do these panels have their own frames? If so why can't you get some taller aluminum brackets- with enough extra height for that vertical air gap on either side. Then cut these into, for example, 15cm lengths and attach one at each side to the panel rather than spanning the full (curved) distance between them. Over a shorter distance the roof will be approximately flat, and even though the straight lines of the panel frames and the aluminum won't be parallel in the finished product you'll have a much easier time with the mounting.


2017 4x4 144 Cargo
I'd rather use rigid panels, better efficiency, more variety.... use Hein's mounts with a spacer underneath to adjust for the curve and proper clearence... 2 holes p/mount and a plate on the interior for added strength, easy to seal


Well-known member
I went with semi flexible. They might be more expensive and less efficient from a solar point of view, but being low profile they should minimise drag and end up saving me more money on my fuel bill than the extra I paid.

Mine are bonded with sikaflex as well as being screwed directly into the roof.


2004 T1N Westfalia
Big advantage of semiflexible is the weight. Also, less mounting hardware.

Downside is the shorter life expectancy.


Well-known member
I am working on a mounting scheme for flex panels. I am attaching pieces of twinwall polycarbonate as used in greenhouses to the bottom of the panel with marine adhesive as suggested by the panel supplier. That provides some stiffness and also allows air below the panel as they work better with cooling. I may have to close off the leading edge if it tends to pull off the roof.

That combination is attached to custom brackets to hold it off the roof. Elevator bolts are embedded in the brackets and locking nuts attach the panels. The panel / twinwall can be replaced if needed without disturbing the roof or peeling off any adhesive.

The custom brackets are 3D printed out of ASA, which is UV resistant and seem strong enough. They match the roof curves and are attached to the roof with VHB tape and two screws through the smaller holes in the top. One bracket has been made invisible so you can see the elevator bolt. The brackets are made in an aerodynamic shape just because I could. I am using Dicor Lap Sealant to seal the holes and edges. The VHB tape alone may be good enough.

Unfortunately, I won't be able to install this until sometime next year so I can't report on it's success or failure until then. I have all the pieces made, but can't take down the van for the install until next year.




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