Application of Dust Mitigation Strategies to Single-Axis-Tracking Photovoltaic Modules in the Semi-Arid Areas of South Africa

Abstract

This paper provides field generated data for single-axis-tracker (SAT) photo voltaic (PV) modules subjected to the semi-arid Northern Cape environment of South Africa. The research objectives are the investigation of the effects of dust soiling on PV module performance and the application of experimental dust mitigation methods. This includes the use of a hydrophobic anti-soiling coating and also the execution of a self-cleaning manoeuvre by the SAT systems. Two SAT systems were deployed to serve as experimental platform, from which data was obtained for a three month period (97 days). Raw data validation is established with comprehensive weather monitoring (ambient temperature, wind speed, wind direction, rainfall, pressure, and humidity), irradiance and PV module back sheet temperatures recorded, in accordance with the IEC61724 standard. An intelligent device was used to extract Current-Voltage (I-V) curves from individual PV modules. Maximum PV module power output is derived from the measured I-V curves, validated with a single-diode curve fitting routine. The comparative study between the different PV modules is done with a performance ratio (PR), defined as the temperature and irradiance corrected performance factor of a PV module. Contrary to the initial hypothesis, results indicated that the hydrophobic coating actually promoted dust soiling. The applied self-cleaning capability of the SAT system did not yield any conclusive results as a dust mitigation method. Finally, interesting in-field observations are discussed.