Lightning and surge protection for rooftop PV systems

Professional planning based on the lightning protection concept

The most commonly used PV systems are rooftop systems. They are particularly prone to damage caused by direct and indirect lightning effects due to their exposed location.

Since the PV system is directly connected to the electrical installation of the building, lightning effects can have severe consequences:

• Damage to the building resulting from direct lightning effects or fire
• Damage to persons inside the building
• Destruction of or damage to electronic devices caused by direct or indirect lightning effects

Comprehensive protection is necessary and should be carefully planned.

Risk analysis – Prerequisite for professional planning

Professional planning including a risk analysis is indispensable for ensuring safe and reliable operation of PV systems. This risk analysis is performed according to EN 621305-2, must be adapted to the relevant building and must take account of lightning and surge protection.

Coordination between the different trades is important

The most important goal of PV installers is to optimise the use of the roof area. Lightning protection installers, in contrast, have to consider the separation distance¹ for the lightning protection system. Lack of coordination may cause considerable problems. Therefore, coordination between roofers / lightning protection installers and installers of photovoltaic systems / electricians is essential not only when constructing a new building, but also when retrofitting roof-mounted systems.

¹ Separation distance: Necessary distance between the down conductor and another earthed metal part of the building.