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: (i) degradation of the electrical circuit of the PV module (cell interconnect breaks; corrosion of the junction box, module cables, and connectors); (ii) mechanical damage to the solar cells (cell microcracks and fractures); (iii) potential-induced degradation (PID) sustained by the module; and (iv) optical losses affecting the module (soiling, shading, and discoloration). The premise of the proposed method 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.