Page 8 - DEHN-protects-photovoltaic-systems

Lightning and surge protection
for solar parks

In many countries, large-scale PV power plants are beco-
ming an important part of the power supply infrastructure.
As a result, they must also meet requirements for stable
network operation. The supply reliability and volume of in-
vestment make it necessary to assess the risk of damage
due to lightning. Damage may be the result of direct light-
ning strikes or of inductive or capacitive coupled voltage.
An integrated lightning protection system, consisting of
external and internal lightning protection, is needed to
prevent damage.
The German supplement 5 of DIN EN 62305-3 and
IEC 61643-32 describe protective measures for free field
PV systems . The basis for an effective lightning and surge
1)
protection system is a meshed earthing system. This pro-
duces a large equipotential surface which significantly
reduces the voltage interference of electrical connecting
cables in case of lightning interference. Mesh sizes
between 20 x 20 metres and 40 x 40 metres have proven
effective.

When selecting surge protective devices, you must diffe-
rentiate between systems with central inverters and systems
with string inverters.
The German supplement 5 of DIN EN 62305-3 and
IEC 61643-32 both point out the minimum discharge
capacity of the arresters to be implemented in solar parks,
making selection easier.

You will find the following protection concepts on the
next few pages:
• Solar parks, configuration with central inverter
• Solar parks, configuration with string inverter

1) DIN EN 62305-3 (VDE 0185-305-3) Supplement 5: Protection against light-
ning - Part 3: Physical damage to structures and life hazard – Supplement 5:
Lightning and overvoltage protection for photovoltaic power supply systems
IEC 61643-32: Low-voltage surge protective devices – Part 32: Surge pro-
tective devices connected to the d.c. side of photovoltaic installations –
Selection and application principles

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