SPLTRAK Abstract Submission
The influence of wind and module tilt on the operating temperature of single-axis trackers
Keith R McIntosh1, Malcolm D Abbott1, Benjamin A Sudbury1, Saurabh Aneja2, Mitch Bowman2, Lance Brown2, Ben Kahane2, Norm Nicholas2, Kristian Nolde2
1PV Lighthouse PTY LTD, Coledale, Australia
/2FTC Solar, Austin, TX, United States

We measure the module temperature Tm in 1P and 2P single-axis trackers, analyzing how Tm depends on wind speed and direction, as well as on irradiance, ambient temperature and module tilt β.  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 β < ~25°, the wind cools the windward side of the tracker by 1–1.5 °C more than the leeward side; but when β > ~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 Tm by, on average, 7.4 °C and 3.3 °C.  Even after calibrating these models to our trackers, they only predict Tm 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 Tm of FTC’s Voyager 2P tracker.