We recommend SureBond190. Here are two links, depending on how much you are buying:
12pk: http://www.roofthings.com/surebond-sb-190-12-pack.html
Single Tubes: http://www.roofthings.com/surebond-sb-190.html
The Panel Guards will come with installation instructions. The best way to clean the surface is to use rubbing alcohol and a clean cloth.