Study on Discriminant Criteria of Aerodynamic Instability of Single-Axis Solar Trackers by Wind Tunnel Test

Aerodynamic instability is a primary reason for the failure of single-axis solar trackers. A section model wind tunnel test of a practical single-axis solar tracker engineering case is conducted to examine the characteristics at different wind speeds. In the wind tunnel test, the vibration angles of photovoltaic (PV) panels are tested for various tilt angles of PV panels and wind turbulence intensities. With the resulting data, the aerodynamic characteristics of single-axis solar trackers in the time domain, frequency domain, and state space are analyzed. Based on the dramatically different characteristics at lower and higher wind speeds, three criteria for discriminating the instability of solar trackers are proposed: the vibration amplitude, energy ratio, and equivalent radius criteria. For validation, the proposed criteria are analyzed in different test conditions of tilt angles of PV panels and turbulent intensities of the wind tunnel. The findings are as follows: (1) Both the vibration amplitude and equivalent radius criteria are effective for determining the instability of single-axis solar trackers with different tilt angles and turbulence intensities. (2) The energy ratio criterion is invalid for high turbulent intensities, but it is useful for different tilt angles of PV panels. (3) The effective value ranges for the three criteria are notably affected by different tilt angles and turbulence intensities.