Lightning protection and PV roof systems in existing buildings

The topic of photovoltaics is currently becoming noticeably more relevant. Large roof areas on industrial plants or pub-lic buildings are equipped with Photovoltaic (PV) systems. The essential requirement is that "the protective function of a lightning protection system must not be impaired by the installation of a PV power supply system." These measures aim to prevent damage to the building (mechanical damage up to and including fire and its effects) and damage to the PV power supply system (power grids, control systems, and electrical protection devices). Suppose PV systems are in-stalled on existing buildings equipped with a lightning protection system as part of preventive fire protection. In that case, special attention must be paid to maintaining the necessary separation distance to the lightning protection system. This article addresses the practical implementation of this essential requirement when installing PV systems with light-ning protection on existing buildings. This study involves experimental investigations at the high-voltage laboratory and comprehensive literature research. It was found that non-separated lightning protection systems often provide inade-quate protection and allow for insulation faults in the PV system. Mainly, arc faults within the PV system serve as po-tential ignition sources.