Protection Against Fault Currents in Photovoltaic Arrays: A Comprehensive Review
DOI:
https://doi.org/10.13052/dgaej2156-3306.4041Keywords:
a.c. fault protection, conductor ampacity, DC back-feed, fault current modeling, multi-string PV, overcurrent protection, photovoltaic arrays, reverse current, string fuse selection, system inspectionAbstract
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 power-electronic topologies and dynamic fault behaviors.
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References
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