Rooftop or ground-mount on-site
Rooftop systems depend on the roof: its structural capacity, remaining service life, orientation, and how much of it is clear of skylights, vents and plant. A roof due for replacement in a few years usually needs to be addressed before panels go on.
Facilities with spare land on their premises can consider ground-mounted systems instead, which avoid structural constraints but compete with any future expansion plans for that land.
