Wind loads on photovoltaic arrays mounted parallel to sloped roofs on low-rise buildings

The objective of this study was to determine the effects of geometry on the wind loads acting on photovoltaic panel arrays with modules mounted parallel to roof surfaces of low-rise buildings. Specific attention was made to determine the effects of varying the spacing between individual modules, G, and the mounting height above the roof surface, H. The photovoltaic system was modeled as an array of 28 modules on a 1/20 scale building model with a roof slope of 30°. In addition, limited studies were carried out with the array mounted on a flat-roof to assess the impact of roof slope. In general, it was found that larger gaps between modules, G, and smaller gaps between the panels and the roof surface, H, were found to yield lower net wind loads. Minimum loads tend to occur for G/H>~1, for the particular panel size considered in the study. Pressure equalization between the upper and lower surfaces of the modules results in the magnitudes of the net panel pressures typically being lower than those for the bare roof surface. A pressure equalization factor, Ceq, was used as a measure of how much the peak net wind loads on the panels are reduced relative to the peak external loads.