The long-term influence of wind and temperature on performance and degradation within an utility-scale photovoltaic plant

Abstract

An inverter-level analysis of a large photovoltaic (PV) plant is evaluated over four years to investigate the long-term performance and degradation caused by wind and temperature effects. The multi-megawatt utility-scale PV plant is located in a semi-arid region in South Africa. The degradation rate is determined using the performance ratio as a comparison metric between the different inverters. The degradation from the first year of operation up to the fourth year shows that different areas of the PV plant have varying degradation rates. The spatial degradation analysis indicates that inverter blocks operating at higher ambient temperatures and lower wind frequency measurements show higher rates of degradation compared to inverter groups operating at lower temperatures and higher wind frequency. Notably, the lowest degradation rates correlate positively with wind direction and frequency from the North and North-East, indicative of a cooling influence on the PV modules. The weather-corrected performance analysis indicates that the most prominent wind direction (North) has the highest mean performance ratio, further supporting the claims that the cooling effect of wind improves performance and efficiency. The widening gap between the best- and worst-performing inverters annually underscores the premise that specific inverters' PV modules degrade at disparate rates within the PV plant. The results of this work present future designs of PV plants that could potentially be optimised to take advantage of wind as a cooling tool, which may further enhance the longevity and sustainability of large PV installations.