Slope effects on highway-side photovoltaics and its wind load calculation method

To evaluate the wind load situation on highway photovoltaic slopes (HPVS), a rigid piezometric wind tunnel test was applied to explore the influences of key parameters on the wind load on HPVS, including the wind direction angle, module inclination angle, slope gradient and array position. The slope gradient factor and wind direction angle factor were proposed, and according to the wind tunnel test, a method was provided to estimate the standard value of the wind load of HPVS based on the wind direction angle and slope gradient. Research results show that the slope effect brings a significant influence on HPVS wind load characteristics, and it is more apparent in the downstream elements of HPVS. At positive wind direction angles, the HPVS shows an amplification effect. The effect manifests as amplified wind pressures at small slopes and amplified wind suction at large slopes. It also presents a wind load blocking effect at negative wind direction angles, while the whole wind load is close to zero at large slopes. Under small slope conditions, the wind pressure on HPVS reaches the highest as the wind direction angle is 30°, while the wind suction is the largest when the wind direction angle is 150°. The HPVS is significantly affected by the change of its module inclination angle. Compared to the one without slope, the HPVS module inclination angle with slope has more severe impact on its whole shape coefficient. With the same slope gradient, the shape coefficient of the HPVS module increases with the rise of the module inclination angle. When the slope gradient is 30°, the changing of the HPVS module inclination angle results in the HPVS wind load turning from wind suctions to wind pressures. When the slope gradient is less than 20°, the shape coefficients of the whole module and the lower surface are less affected by the slope gradient at positive wind direction angles. The slope effect is relatively insignificant. When the slope gradient is higher than 20°, the slope gradient shows an increasing remarkable influence on the shape coefficients of the whole module and the lower surface at positive wind direction angles. Meanwhile, the slope effect strengthens gradually. When the slope gradient is close to the module inclination angle, the whole HPVS wind load is slightly affected by the slope structure. In summary, the research results provide a foundation for the wind load calculation in HPVS design.