Analytical modeling of reversible performance loss of PV modules and module arrays

A new analytical model for simulating the performance of PV modules and module arrays vs. time is presented, which includes reported functions for the performance loss due to module degradation and new functions for the performance loss due to performance-reducing events, which may be reversible through good operations and maintenance (O&M) practices and/or spontaneous natural processes. The new functions represent the novelty and main contribution of the present study. The proposed analytical model allows simulating both the fall in performance expected after performance-reducing events and the subsequent raise expected after removing the cause of performance-reducing events. Accurate continuous non-linear fits to reported experimental curves of performance vs. time of seven PV devices affected by various modes of reversible performance-reducing events validate the model. As applications, the PV-performance of real PV-devices is simulated in the case of absence, delay, anticipation, and schedule variation of O&M practices. The relevant loss or gain of PV-energy output is evaluated. Based on the continuous fits, reliable non-linear performance-loss rates can be determined. Model and results are discussed.