Fitting a solar panel to my caravan roof

I am sure many of you have already done this so i am asking for advise please. There is no way i am drilling holes in my roof!! however i understand there are corner brackets on the market you you just fix to the panel then stick with an adhesive. What brackets and what adhesive would you recommend? I have all the other components and plan to use the Panel when hookups are not available on CL sites. The electrics will be on the outside of the van and fed through the battery compartment and fixed in the inside of the van by a plug and remove ouside cables when not in use. Any advise will be gratefully received. 

Kind regards DevonBoy13