The tape is holding the twin wall firm, no lifting at all. Can’t really tell if the panel is expanding but given that my panel is attached to the twin wall using the eyelets it’s free to expand and contract if needs beI am looking at this as my current panel has failed and will need to be replaced. I do not want to replace a panel every two or three years. I will probably go down the same route by using 4mm twin wall, how secure is the 3M tape? Any sign of lifting due to rain etc? Can you tell if the panel has any movement to allow for heat expansion?