Protection Against Fault Currents in Photovoltaic Arrays: A Comprehensive Review

Abstract

Fault currents in photovoltaic (PV) arrays present unique challenges for system designers, particularly when multiple strings are connected in parallel. This review consolidates fault-current modeling, international standards, and practical guidelines to establish a comprehensive protection framework for PV installations. In this paper, single-string and multi-string fault scenarios are analyzed, deriving expressions for short-circuit and reverse-current contributions under high-irradiance conditions. Using international standards as reference points, the conditions under which string-level overcurrent protective devices become mandatory is quantified. Conductor ampacity requirements are shown to inherently satisfy “overload” protections if cable sizing exceeds maximum design current per string; however, in unfused configurations, cable ratings must be verified against the worst-case reverse-current from healthy strings. The paper also addresses the a.c. – side short-circuit protection, noting inverter contributions and grid-sourced fault currents. Finally, commissioning and inspection procedures are outlined to ensure compliance with labeling and protection mandates. The findings support safer, more cost-effective PV system design and highlight areas for future research in advanced powerelectronic topologies and dynamic fault behaviors.