Fault identification in crystalline silicon PV modules by complementary analysis of the light and dark current-voltage characteristics

This article proposes a fault identification method, based on the complementary analysis of the light and dark current-voltage (I-V) characteristics of the photovoltaic (PV) module, to distinguish between four important degradation modes that lead to power loss in PV modules: (a) degradation of the electrical circuit of the PV module (cell interconnect breaks; corrosion of the junction box, module cables and connectors); (b) mechanical damage to the solar cells (cell microcracks and fractures); (c) potential-induced degradation (PID) sustained by the module; and (d) optical losses affecting the module (soiling, shading, discoloration). The premise of the method that is proposed is that different degradation modes affect the light and dark I-V characteristics of the PV module in different ways, leaving distinct signatures. This work focuses on identifying and correlating these specific signatures present in the light and dark I-V measurements, to specific degradation modes; a number of new dark I-V diagnostic parameters are proposed to quantify these signatures. The experimental results show that these dark I-V diagnostic parameters, complemented by light I-V performance and series resistance measurements can accurately detect and identify the four degradation modes discussed.