>>/934780/
Postieneet has rails so would be stupid not to get hard mounts. 
Hard mounts can carry quarter ton secure storage cases, that's all the shit which would otherwise cram up your van and make it unliveable. It you're going at 90kmph with a solar panel on your roof, you're going to have a bad time. If it were me I'd just clip mount the panel to the rails and angle it off the case. You can't stop someone smashing your panel, so just make sure nobody can steal it intact