Personally - I would NEVER just glue anything to the roof of any vehicle. Industry advice is to always securely bolt your panels to underlying framing - not just the surface metal. Some are saying that they have glued theirs and have no trouble - yet! Think what your insurance company might say in the case of an event - where a panel came off and caused damage, or worse to other vehicles and people. Just don't do it - don't glue, even with the super strong stuff others are advising - it is just an accident waiting to happen - and as has been posted, these accidents are not uncommon of glued panels coming off on the highway. I belong to a UK based campervan group - there are some sorry members there who thought they could get away with sing the strongest glue on the market. Ask any professional solar installer - they will set you straight.