Degradation and reliability analysis of photovoltaic modules after operating for 12 years: A case study with comparisons

Abstract

The long-term performance monitoring and characterization of field-exposed solar photovoltaic (PV) modules are essential for efficient power generation. This paper is an attempt at performance evaluation of the amorphous silicon (a-si), Heterojunction Intrinsic Thin layer (HIT), and Multi-Crystalline (mc-si) technologies after twelve years of outdoor exposure in the composite climate of India. Characterization techniques such as Visual Inspection, Infra-Red (IR) Thermography, Electroluminescence (EL) Imagining, and Electrical characterization have been carried out. I–V measurements, power losses, current degradation, and voltage degradation calculations are carried out. The percentage of electrical decline is 8.61%, 2.73%, and 29.08%, for Isc, Voc, and PMP respectively in a-si solar modules. For HIT modules 1.97%, 0.68%, and 0.48% for Isc, Voc, and VMP respectively. Finally, for the mc-si PV modules, these are 3.76%, 0.5%, and 1.44% for Isc, Voc, and PMP respectively over 12 years. The average degradation rates are found to be 1.24%/year, 0.14%/year, and 1.50%/year for a-si, HIT, and mc-si modules respectively. The EL imagining of the a-si modules shows the localized shunt over the surface of the modules as well as disconnected cell interconnects whereas no such defects are over the m-ci and HIT modules.