Wind flows and pressure distribution around a PV panel mounted on the gable roof of a residential building

Abstract

Recent years have seen numerous improvements in the field of renewable energy and has resulted in the usage of Photovoltaic panels (PV) on the rooftops of low-rise residential buildings. This has raised a question about the wind pressure loading on and the flow around these roof mounted panels. Although significant wind tunnel research and some full scale studies have been undertaken in the past to explore both the mean and peak pressure loading of PV panels and the roof, the wind velocity profile around these panels, an equally important variable, has been ignored. The present study attempted to bridge this gap by carrying out flow visualization studies parallel to a wind tunnel experiment. The experiment was conducted in a boundary layer wind tunnel on a 1:20 scaled, 22.5° tilted roof house placed in atmospheric boundary layer flow and the pressure distribution on the panel and the roof (both mean and peak pressures) were measured for thirteen different wind angles and six different panel locations. The research used the commercial CFD software, ANSYS CFX for a steady state numerical study to emulate the full scale experiment and determine the wind flow patterns around the panel and the roof. These were used to explain the pressure behaviour on the roof and the panel. The use of flow visualization to elaborate the pressure contours was fruitful as the study was able to uncover several interesting flow features which gave rise to the observed, and sometimes, the unusual pressure distributions. The presence of flow separations, reattachments and back flows under the panel were recorded and reported in the results section for this study with support from the empirically generated pressure contours. The study also determined the best location for the positioning of the panel by analysing the net and point pressures on the panel.