In photovoltaic (PV) arrays with several strings in parallel certain fault conditions may lead to potentially damaging reverse currents for PV modules. The Australian Standard AS/NZ5033:2005 Installation of Photovoltaic (PV) Arrays deals with fault current protection for both cabling and PV modules and forms the basis of the development of the international draft standard IEC 62548 Ed.1: Installation and Safety Requirements for Photovoltaic (PV) Generators. This international standard development work highlighted the need for improved understanding of the application of fuses in PV arrays and this paper consequently examines in detail requirements for fusing in PV arrays in view of various fault and environmental conditions with respect to protecting both cabling and PV modules.
It reviews and discusses fusing requirements and ratings of the current PV array installation standard. Test results of typical fuse characteristics of fuses used in PV arrays are presented obtained using both a PV array simulator and a PV array. The paper then examines the relationships between acceptable reverse current levels and exposure durations of reverse currents on PV modules and compares them with trip currents of fuses and typical time delays experienced with fuse tripping. The work contributes to the recommendations for the IEC standard on PV array installation and safety requirements.