Wind loads on stand-off photovoltaic systems on pitched roofs

Stand-off photovoltaic systems are a popular measure for retrofitting of existing pitched roofs. Panels are generally mounted parallel to the existing roof coverings, usually roofing tiles. Full scale and wind tunnel experiments have been performed to determine the net uplift loads on these systems, which can be applied to calculate the loadbearing system. In the wind tunnel, the effect of distance between panel and roof has been investigated. Results show that loads can be expected that are substantially lower than the external loads on the roof surface, as given in wind loading standards. The effect of distance between PV system and roof surface is relatively small. The loads on the underlying roof are not significantly higher or lower compared to the case without system.