The influence of wind and module tilt on the operating temperature of single-axis trackers

We measure the module temperature
$T_{m}$
in 1P and 2P single-axis trackers, analyzing how
$T_{m}$
depends on wind speed and direction, as well as on irradiance, ambient temperature and module tilt ß. On a clear day, we find that the typical temperature variation within a tracker is 1-4°C for 1P and 2–6 °C for 2P trackers, where the coolest region tends to be nearest the torque tube. Whether for 1P or 2P, we find that when ß < ~25°, the wind cools the windward side of the tracker by 1-1.5 °C more than the leeward side; but when ß > ~25°, the upper side is 0.5-1.5 °C cooler than the lower side, irrespective of wind direction (for wind speeds < 5 m/s), We also find that the commonly used NOCT and Faiman temperature models overpredict
$T_{m}$
by, on average, 7.4 °C and 3.3 °C. Even after calibrating these models to our trackers, they only predict
$T_{m}$
at any given time to ±6.6 °C with 95% confidence. Without adding any free variables, the modelling accuracy is improved to ±3.8 °C by accounting for radiative loss to the sky and transient effects; the accuracy is improved further to ±2.8 °C by accounting for module tilt, wind direction and ground temperature. This study expands upon the PV industry's understanding of how single-axis trackers are influenced by wind speed, wind direction, and tilt, and it refines our ability to accurately predict
$T_{m}$
of FTC's Voyager 2P tracker.