How to install flexible solar panels on a curved roof

@AnneWatson's spot on about ventilation—that's what catches most people out. I've got flexible panels on my narrowboat and the difference between gluing them flat to the roof versus creating an air gap is night and day for longevity.

The adhesive alone (even proper marine-grade stuff like 3M 5200) will eventually fail if you've got moisture trapped underneath. Thermal cycling makes it worse—materials expand and contract at different rates, and any water trapped in there will degrade both the adhesive and whatever substrate you're mounting to.

What actually worked for my setup: used small aluminium spacer blocks (about 20mm) along the frame to create that crucial air gap. Allows water vapour to escape. I also drilled a couple of small weep holes near the bottom edge so any condensation that does form can drain out.

The flex panels themselves handle the mounting method better than rigid ones would, but they're still relying on that adhesive for a significant portion of the load. Proper mechanical fastening through the frame to solid structure is non-negotiable—adhesive as secondary backup only.

Worth the extra effort up

Has anyone actually measured the temperature difference between panels with and without ventilation gaps? I'm considering flexible panels for my van conversion and @AnneWatson's point about airflow is making me reconsider my mounting plan. What spacing are people using—just enough for a finger, or more substantial?

Been there with my hut roof—the ventilation gap made a measurable difference, about 8-10°C cooler panel surface in summer. I used thin aluminium spacers at intervals rather than full battens, keeps airflow but avoids complexity. Victron's monitoring gear picked up the efficiency gain. Worth the extra effort before you're stuck with panels permanently adhered.

Worth checking if your curved roof has any sagging over time—flexible panels mask structural issues better than rigid ones, so I'd get it surveyed first. Also, what's the pitch angle? Shallow curves can trap water, which causes panel delamination. I've seen this on motorhome roofs after a couple winters. What's your roof material?