Performance Evaluation of Solar Photovoltaic Arrays After 18 Years of Field Operation

Abstract

This paper presents the performance of arrays of mono- poly-crystalline silicon (C-Si) solar photovoltaic (PV) modules (93 nos.) after operation for a period of 18 years. The beginning of deterioration commences with the damage to packing and its adhesion leading to intrusion of environmental O2 and moisture. Global performance deterioration rates of modules are 0.5 to 0.6 %/year over a 20–30 year horizon. The present study indicates that the degradation of the performance of the array is 1.43 %/year which implies that the balance of the array (other than modules) account for around 0.8 %/year due to increased junction losses, wiring losses, leakage losses and module electrical mismatch. Delamination and discoloration of encapsulant and breakage of backsheet are causes of performance degradation in the 20+ years time span. Operation and maintenance practices when not rigorous initiate degradation in cell performance through electrical mismatch and back feed into inactive cells through circulating currents...