Experimental Investigation of the Wind Loading on Solar Panels: Effects of Clearance off Flat Roofs

Abstract

The paper presents the results of a comprehensive wind tunnel study dedicated to addressing the effects of the underneath array clearance on wind loading of roof-mounted solar panels. Indeed, the array clearance has a crucial influence in many respects ranging from its consideration in the wind tunnel modeling to its impact on structural safety. A set of atmospheric wind tunnel experiments was carried out on three configurations of a multipanel solar array mounted on a flat roof immersed in a simulated atmospheric flow of open-country exposure. The solar array was placed at three clearance heights above the roof, namely, 0, 20, and 40 cm (in full scale). Wind tunnel measurements of the mean and peak pressures on both bottom and top surfaces of the solar panels as well as of net pressures across the panels were carried out. The results show that the impact of the underneath array clearance on the panel wind-induced pressures depends highly on the wind direction and the location of the panel within the array. Generally, the wind-induced pressures on solar panels when lowering the array clearance become quite severe and may peel off the panels from the supporting racking system; on the other hand, at such clearance installation, the panels are subjected to lower downward net pressure. Furthermore, the study highlights the potential uncertainties in the wind tunnel experimental results that could be deemed as actual design loadings when the underneath clearance is of concern. This has important ramifications on the formulation of design provisions to be used by solar panel professionals.