Aerodynamic wind loads on a solar away

The aerodynamically-induced torque on a solar panel containing six slender, parallel modules was investigated. A simple predictive model for determining the peak system torque coefficient was developed. This model depends on the mean torque coefficient, the rms coefficient due to vortex shedding, the freestream turbulence intensity, the correlation along the individual panel modules and the correlation between the modules during extreme events. The peak loads are also dependent on the wind angle, and to a lesser extent on the declination angle and module angle. An attempt to normalize the mean coefficient with respect to these three angles was met with limited success. Rather, the peak coefficient was examined for the worst cases of the module and declination angles and three different wind angles. The peak system torque was generally observed to occur at wind angles near the diagonals to the panel (45 degrees, 135 degrees, 225 degrees and 315 degrees) although large loads also occurred at 270 degrees, where wind is in the plane of the panel, perpendicular to the panel modules. In this case, there was a strong lock-in of the vortex shedding among the six modules. The largest loads, how ever, occurred at a wind angle of 330 degrees where there was limited vortex shedding. In this case, the bulk of the fluctuating torque came from turbulent velocity fluctuations in the oncoming flow. The latter two cases were examined in detail.