A roof-based system for suspending photovoltaic modules, such as solar panels, relative to a roof surface without penetration of the roof surface. Cables under tension span the roof surface, with opposed ends of the cables securely mounted to generally C-shaped cable arm assemblies that wrap around the roof edge for connection via pivot joint assemblies to the underside of an overhanging eave, the immediate side wall of the structure below the roof, or directly to roof edge fascia. The system is completely contained to the roof area with no penetration of any parts through the roof surface. Vertical and horizontal rails set upon the roof surface, but not attached to the roof surface, support the weight of the photovoltaic modules attached thereto, while the cables, under tension, hold down the rails in position relative to the roof surface.