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2.3 Surge protection devices
(SPDs) for PV installation
WARNING!
Induced surges are the most likely cause of lightning damage in the majority of installations,
particularly in rural areas where power is typically supplied via long overhead power lines.
Surges can affect both the PV generator line and the AC cables leading to the building.
Lightning protection professionals should be consulted for final application. With suitable
external lightning protection, the impact of a direct lightning strike on a building can be
weakened in a controlled manner and the lightning current can be diverted into the ground.
The installation of SPDs to protect the inverter from mechanical damage and excessive
stress includes a surge arrester in the case of a building with an external lightning protection
system (LPS) when a separation distance is maintained. To protect the DC system, a surge
protection device (SPD Type2) should be installed at the end of the DC wiring of the inverter
and on the array between the inverter and the PV generator when the voltage protection
level (VP) of the surge arresters is greater than 1100V, an additional SPD type 3 is required
for overvoltage protection for electrical devices.
The formation of loops in the system must be avoided. This short routing and bundling
requirement includes all associated ground bundling conductors.
To protect the AC system, surge protective devices (SPD Type2) should be installed at the
main input point of the AC supply (at the load cutout), which is located between the inverter
and the meter/distribution system; SPD (test pulse D1) for signal line according to EN
61632-1. All DC lines should be laid as short as possible; plus and minus lines of the string or
the main DC supply should be bundled.
When installing the PV system, surge protection with surge arresters should be
provided. The grid-connected inverter is not equipped with SPDs on either the PV input side
or the grid side.
Spark gap devices are not suitable for use in DC circuits once they are conductive; they only
stop conducting when the voltage across their terminals is typically below 30 volts.
Lightning causes damage either from a direct strike or from surges due to a nearby strike.
Machine Translated by Google
