Right, I have refreshed my memory using photos I took and reading my thread from when I installed it. First of all, I LIED, there are no ridges on my roof!
It does have a recessed section, looking like a blank for a sunroof but probably a space for a (very small) solar panel, and I was concerned about water making its way in an pooling there.
You can see it in this 2017 pic
View attachment 36188
So to avoid this, and try and get some airflow to the underside of the panel, I ran the adhesive in 'stripes' about 75mm apart along the length of the panel and along the outsides of the longitudinal edges. I didn't seal across the front as, as you can see above, the roof is front hinged so needs to be able to drain from the front. The panel is bonded direct to the roof with no vinyl inbetween. I used 2 tubes of the above adhesive.
All the pictures of the install, and my documented ineptness, are in this thread
Solar Panel Fitting To Front Hinged Roof