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Modelling PV Module Lightning-Induced Response: The Oversimplified, the Overestimated, and the Overlooked
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  • Kurt Coetzer ,
  • Hermé Smit ,
  • Pieter Gideon Wiid ,
  • Arnold Rix
Kurt Coetzer
Stellenbosch University

Corresponding Author:[email protected]

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Hermé Smit
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Pieter Gideon Wiid
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Arnold Rix
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Abstract

This study presents a simulated analysis of the response of a photovoltaic (PV) module to a single indirect lightning stroke. It does so by separately passing positive and negative 20 kA, 8/20 µs lightning current waveforms through a wire in space, located 1 m from the centre of a vertically-orientated PV module, and monitoring the voltages and currents at the PV module output terminals. Typically, literature uses an unvalidated, wire-based equivalent model for this purpose. Recent research has demonstrated the substantial shortcomings of such a wire-based equivalent model when viewed from the following three perspectives: differential mode impedance, internal coupling, and differential mode radiation. What sets this study apart is that it consolidates the novel advances made in multiple recent PV-orientated studies, all of which are centred around the high-frequency modelling of PV modules. These advances include improved three-dimensional structures which are coupled to nonlinear circuits using a hybrid simulation approach. These measurement-validated novel hybrid models have been shown to produce results which are substantially more accurate than the wire-based equivalent models when examined from the three aforementioned perspectives. This study progressively implements these models, demonstrating the absolute necessity of properly incorporating each aspect. Wire-based equivalent models are shown to produce overestimated levels of induced voltage and current. Furthermore, the use of linearised circuits to represent the inherently nonlinear operation of PV cells - a practice prevalent in such research - is demonstrated to be an oversimplified approach. Finally, the importance of considering the behaviour of the often-omitted, and therefore overlooked, bypass diodes is emphasised.Â