Wind load characteristics of photovoltaic panel arrays mounted on flat roof

Abstract

To quantify design wind load of photovoltaic panel array mounted on flat roof, wind tunnel tests were conducted in this study. Results show that the first and the last two rows on the roof are the most unfavorable ones regarding to the wind load. Influences of array spacing, panels’ tilt angle and parapet height on wind load of the panels are studied. Most unfavorable lift force of panels decreases with increase of array spacing for middle located panels. The aerodynamics are similar to flow over repeated hills. Middle located unit got greater turbulence, which leading to unfavorable C fp_min. While the changing amplitude of most unfavorable wind pressure is small increase with array spacing. C fp_max and C fp_min of panel units shows quite strong dependence on tilt angle. There is significant pressure equalization for small tilt angle cases. The local flow separation is responsible for C fp_min of larger tilt angle cases. Parapet height of 2 h (h is the panel height projected on the vertical plane) is the critical height for C fp_max and C fp_min. Increasing parapet height can significantly reduce the wind load of panel units. Design pressure coefficient of the basic working condition with different area sizes at different location are proposed.