Page 4 - DEHN-protects-photovoltaic-systems

Lightning and surge protection for
rooftop systems

Rooftop systems are extremely exposed and therefore par-
ticularly prone to damage caused by direct and indirect
lightning effects. Since the PV system is directly connected
to the electrical installation of the building, lightning effects
can have severe consequences for the building itself, the
people inside and electrical devices.

According to the current state of scientific knowledge,
PV modules do not increase the risk of a lightning strike
which means that the need for lightning protection
measures cannot be derived directly from them. The risk
of damage due to lightning should there be assessed in
compliance with IEC 62305-2 . National regulations,
1)
e.g., the state building code, should also be considered.
A professional lightning protection system consists of
• External lightning protection with air-termination
systems, down conductors and an earthing system
• internal lightning protection for lightning equipotential
bonding and surge protection

The German national supplement 5 of DIN EN 62305-3
describes protective measures for external and internal
lightning protection when using PV power supply systems.
Implementation of the protective measures described there
2)
has also proven its worth on an international level .
In addition, IEC 61643-32 and IEC 60364-7-712 provide
information on selecting and implementing surge protective
devices in PV power supply systems .
3)
Both IEC 61643-32 and supplement 5 of DIN EN 62305-3
describe three different applications for PV installations
on buildings:
• Buildings with PV systems, without external
lightning protection
• Buildings with PV systems, with external lightning
protection and sufficient separation distance
• Buildings with PV systems, with external lightning
protection, without sufficient separation distance

1) IEC 62305-2: Protection against lightning – Part 2 Risk management
2) DIN EN 62305-3 (VDE 0185-305-3) Supplement 5: Protection against lightning -
Part 3: Physical damage to structures and life hazard – Supplement 5: Lightning
and overvoltage protection for photovoltaic power supply systems
3) IEC 60364-7-712: Low voltage electrical installations – Part 7-712: Requirements
for special installations or locations - Solar photovoltaic (PV) power supply systems
IEC 61643-32: Low-voltage surge protective devices – Part 32: Surge protective
devices connected to the d.c. side of photovoltaic installations – Selection and
application principles

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