Wind Considerations for Loose-Laid and Photovoltaic Roofing Systems

In recent years, markets for photovoltaic (PV) panels/modules have been dramatically growing, in part due to an increase in efficiency and reduction in costs of such devices. Various systems incorporating PV modules have been developed for a broad range of applications, mainly as solar-energy-based sources of electricity integrated with traditional distribution networks. Loose-laid systems placed on roofs of industrial and residential buildings belong to this category. This paper discusses wind loading and considerations involved in assessment of wind resistance of loose-laid roofing systems, including those incorporating photovoltaic and other solar-energy devices. First, the wind-induced pressure and the net wind loading exerted on permeable generic roofing systems are discussed. The wind tunnel results, point pressures measured in a roof corner region with/without a roofing system, are used to calculate the net wind uplift and to demonstrate the effects of the system permeability/flow resistance on the uplift. Subsequently, the wind loading on and resistance of a generic PV roofing system are discussed. Finally, the methodology developed at the Wind Engineering and Fluids Laboratory (WEFL) to formulate design guidelines for loose-laid roofing system with/without PV elements is presented.