The dual panels are mounted externally, ideally within 10 meters pipe-run distance of the Bunsen Air unit. There are options for the positioning of the panels:
Pitched roof – you may prefer to mount the panels on the roof to keep them out of the way.
Vertical Wall – there is no problem mounting the panels on any vertical wall
Flat roof or ground mounted – as long as there is a minimal pitch then the flat surface is no problem.
In addition the panels can be mounted in Landscape or Portrait, and where space is a limiting factor, then the panels can be placed one behind the other (like a sandwich) to take up the space of just a single panel.