OSHA regulation 1926501(b)(1):
Unprotected sides and edges." Each employee on a walking/working surface (horizontal and vertical surface) with an unprotected side or edge which is 6 feet (1.8 m) or more above a lower level shall be protected from falling by the use of guardrail systems, safety net systems, or personal fall arrest systems.
Also, if a roof pitch is greater than 4.5/12 (that roof looks like 6/12) will require a flat surface around the equipment or an attachment point for a harness.
No way in hell I service those units as they are.