OVER-CURRENT PROTECTION IN PV ARRAY INSTALLATIONS
Martina Calais, Nigel Wilmot, Andrew Ruscoe, Óscar Arteaga, H. Sharma · 2008
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 Installation of Photovoltaic (PV) Arrays recommends fuses to protect both cabling and PV modules in case of the occurrence of these fault conditions. The above standard forms the basis of the development of the international IEC draft standard on 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 array 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. This testing utilised both a laboratory power supply and a PV array. The paper also examines the relationships between acceptable reverse current levels and exposure durations of reverse currents on PV modules and compares them with trip current of fuses and typical time delays experienced with fuse tripping.