I’ve had two 100w from Photonic Universe for about three years, still going strong. (P.S I’ve never tried to walk on them, or anything silly like that)
I put a rivnut through a higher section of the roof for each corner of the panel and then used washers and bolts to secure the corners, dab of sealant to stop leaks. Then I used a bead of sikaflex along the leading edges of the panels to prevent them lifting or flapping in the wind (I think I did all the edges i.e. sides and back)
If I ever need to remove them, I suspect it will take longer to remove the bolts than it will to run a stanley knife around the edges of each panel 🙂
(I didn’t bother with an airgap, at the time I couldn’t see anyone suggesting it was necessary for flexible panels, even so, I’d rather have low profile and lightweight panels with less efficiency)