Degradation analysis of photovoltaic modules based on operational data: effects of seasonal pattern and sensor drifting

Degradation analysis of photovoltaic (PV) modules based on real operational data is essential to the future development of the PV industry. Weather conditions and system drifting often lead to large uncontrollable fluctuations in operational data, which present great challenges for calculating degradation rates of PV modules. In this paper, we propose a new numerical two-step approach to overcome these difficulties. In particular, we will show that our method is able to eliminate effects of seasonal patterns and systematic sensor drifting in evaluating degradation rates of PV modules. The method is applied to the six-year operational data of a solar PV system installed at CA United States. We demonstrate that our approach can greatly improve the degradation calculations, compared with other widely used methods.