Ensure your panel/s are mounted securely to your vehicle roof. 

Panels over 150 watts should be bolted to the vehicle frame, rather than using glued plastic mounts. 

Always take the advice of a professional installer who can look at your vehicle and recommend a fitting based on your needs.  Not all vehicle roof tops are the same, they all have a variety of materials, age, paint strength etc etc.  We cannot advise you remotely on the correct solution for your vehicle, we can only make suggestions.  It needs boots on the ground and eyes on your installation, be mindful that no-one should be advising you of what will work for you, over the phone or email, we won't and nobody should.  Don't be the driver below...