Prediction and controlling torsional instabilities in photovoltaic solar trackers

Abstract

To reduce the construction and installation costs, the rigidity of the single axis solar tracker structures has been systematically reduced. Consequently, some plants of solar trackers suffer one-degree-of-freedom flutter in torsion, reaching to collapse part of the plant. In this paper, the prediction tools of this phenomenon are analyzed. The estimation of the flutter critical wind velocity from construction standards, CFD and wind tunnel test are compared and evaluated. In addition, some methods to increase the flutter critical wind velocity are presented. Wind tunnel results show that, actually, the instability is a combination between a static increase of the torsional angle (which does not reaches torsional divergence) and one-degree-of-freedom flutter. As this kind of flutter is due to the alternative vortex shedding on both sides of the solar panel, to increase the critical speed, methods based on passive or active flow control (by means of DBD plasma aerodynamic actuators) are studying. It is looking for devices that avoids the alternative vortex shedding, or at least, decreases its intensity.