Experimental study on the influence of parapet porosity on wind loads of roof-mounted photovoltaic panels

Yuchao Xia , Zhikun Bai , Guangen Zhou , Shuifu Chen

Abstract

This study examines the effects of parapet porosity on the aerodynamic loads on roof-mounted photovoltaic (PV) panels. Wind tunnel tests were carried out in the ZD-1 boundary-layer wind tunnel at Zhejiang University to capture the wind pressure variations on the PV panels under different levels of porosity. A rigid model with a scale ratio of 1:50 was fabricated, mimicking a low-rise building with five rows of PV panels on the roof. Four distinct levels of parapet porosity (81%, 49%, 25%, and no parapet) were tested at a fixed panel tilt angle of 5°. The methodology and results are presented, highlighting the statistical analysis of wind pressure coefficients, encompassing means, standard deviations and the identification of maximum and minimum peak values in various wind directions. Key findings reveal that oblique wind directions (30°–75°, 120°–165°) generate peak pressure extremes through conical vortex formation at roof edges, with maximum mean pressure coefficients reaching 2.27 (30°) and -2.63 (135°) in the no parapet case. It is observed that while parapets can attenuate wind loads, their effectiveness in load reduction is affected by the porosity of the parapet. Optimal parapet porosity (49–81%) reduces mean and extreme pressure coefficients by up to 60.3% and 51.7% in front-row modules. In comparison, when the porosity is further decreased from 49% to 25%, the mean and extreme pressure coefficients only show a limited reduction (<10%), while localized pressures are exacerbated.

Key Words

parapet porosity; PV panels; roof-mounted systems; wind load; wind tunnel testing

Address

Yuchao Xia — Zhejiang Southeast Space Frame Co, Ltd, Hangzhou, China
Zhikun Bai — College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058, China
Guangen Zhou — Zhejiang Southeast Space Frame Co, Ltd, Hangzhou, China
Shuifu Chen — College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058, China

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