Degradation Analysis and Long-Term Performance Forecasting of a Dual-Axis PV Solar Array in South Africa

This paper presents a five-year field degradation study and 20-year projection for a 12.8 kWp mono-crystalline dual-axis photovoltaic (PV) array at the Central University of Technology, South Africa. Annual net energy data (2019–2023) obtained from SunnyPortal were compared against a standard warranty-based compound model. This model assumed a 2.5% first-year loss followed by 0.6% annually. Measured cumulative degradation reached only 3.96%, successfully outperforming the model’s prediction of 4.23%. The first-year drop of 2.47% aligned with stabilization expectations. Furthermore, subsequent annual losses consistently stayed below the nominal 0.6% threshold, indicating highly stable in-service behavior. Based on a conservative extrapolation of 0.6% per year from the 2023 baseline, the system is projected to incur a total compounded loss of 11.9% by 2044. This sustained outperformance validates the efficacy of data-driven operations and maintenance in semi-arid climates, providing essential inputs for accurate lifecycle cost estimation and long-term revenue planning.