In-situ performance investigation of the world's pilot canal top solar PV system in India

Abstract

Water-mounted solar photovoltaic systems offer significant advantages over traditional installations, but knowledge of their long-term degradation under extreme conditions, particularly sustained high humidity, remains limited due to their nascent stage of development. To address this gap, this study analyzes the decade-long degradation trend of the world's first canal-top SPV (CSPV) installation of its kind, situated in India. It also investigates system performance through in-situ characterization analysis employing Drone Thermography, String/module I-V, Electroluminescence, and Ultraviolet Fluorescence imaging techniques. The CSPV system exhibited an annual degradation rate of 1.30 % over the decade, with the best-fitted degradation trend described by the Langevin-based exponential model. Ethylene Vinyl Acetate browning affected nearly all CSPV modules, with the in-situ analysis revealing 14.98 % degradation at about 11 years of operation, exceeding expected degradation limits for most PV strings. Furthermore, increased occurrences of solder failure, bus-bar-related degradation, increased series resistance, elevated voltage degradation, and darker inactive regions towards negative polarity modules indicated metallization corrosion and early potential-induced degradation, highlighting the adverse impact of higher humidity. This research provides essential insights for design engineers, module manufacturers, and the maintenance team to quantify and address defects and anomalies in such systems, facilitating targeted actions for diagnosis and resolution.