When Adhesive Tape Is Not Enough

I wanted a photovoltaic panel to charge the battery box that I use for my telescopes.   Nice panel.  It produces 17V unloaded.  With the 12VDC plug it produces 13.3VDC when charging.  Just right to avoid overcharging.  (I guess that because of the plug there is some regulator to keep the voltage in the right range for its intended use.)

Originally I used adhesive tape to stick it to the clear plastic window of the telescope shed.  Of course it gets warm in there so within a couple days, the panel was on the floor.  The window pane is held in place by 7 or 8 screws through the pane into the wall.  The panel has several mounting holes.  Simple solution. Unscrew two of them and back through the mounting holes into the wall.