Sorry but how long is a piece of string? Not being mean but every job is different.
Mine are all bolted down three inches above the roof on an Aluminium frame which in turn is bolted to the guttering with some alloy angle.
I would not consider plastic as the sun destroys plastic relatively quickly in our climate even with the UV filters they add to the plastic these days.
The fixing method depends on whatever will suit your particular vehicle and any place they can be attached securely with as few holes through the roof as possible.
I expect someone with in depth knowledge will come along with expert advice. There seems to be someone on here with knowledge in all sorts of areas which makes this forum so good and informative.
We used Aluminium bracketry on ours as the frame of the solar panels is Aluminium and so we didn't want to introduce a metal that differs, used pop-rivets from barcket to solar panel frame, and riv-nuts and body panel Sikaflex for the bracket to the roof sticks like 5h1t!!
Hope that helps.
Mark
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Mark & Linda
A man who asks a question is a fool for five minutes, but ask no questions and your a fool for life!!
As mentioned make sure you use aluminum so that you don't get any issues with dissimilar metals. The main thing to ensure it that the panel is at least 30 mm above the roof to ensure the panel gets a good flow of air under it. If not the panel will get too hot when operating and will be derated. Good luck with the job
Regards
briche.
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