Experimental investigation of wind pressures on photovoltaic (PV) panel installed parallel to residential gable roof

The study was conducted to investigate the wind pressures on PV panels installed parallel to a 30 degrees pitched gable roof, with a special focus on the effects of roof clearance. The wind pressures on the two sides of the scaled panels with four clearances, i.e., ranging from 5 cm to 20 cm with an interval of 5 cm, were tested. The pressure coefficients over taps and zones were examined and discussed. The results show that the most critical positive and negative area-averaged peak net pressure coefficients were comparable in magnitude. With a clearance of 10 cm, the critical positive and negative values were 1.13 and -1.08, respectively, and both occurred at theta = 0 degrees. With effective area of 3.7 m2, the critical positive values increased 26.6 %, 8.3 % and 11.7 % as clearance ranged from 5 cm to 10 cm, 10 cm to 15 cm, and 15 cm to 20 cm, respectively, while the critical negative values changed little when clearance was less than 15 cm, but increased 18.8 % when clearance increased from 15 cm to 20 cm. However, the associated unfavorable wind directions of critical positive and negative values were at theta = 0 degrees, and oblique wind, respectively, remaining nearly unchanged with the increasing of clearance. The tested critical positive and negative area-averaged peak net pressure coefficients were smaller than the values calculated by standards, indicating that the wind resistant designs of roof-mounted PV panels according to the mentioned standards are quite conservation.