These are the most frequently asked questions about the protection of PV systems:
Q: Is there an increased lightning risk if PV systems are installed at or on top of a building?
A: No, the installation of a conventional PV system at or on top of a building does not increase the risk of a lightning strike.
Q: Which are the standards to be observed for protecting PV systems in the event of a lightning strike?
A: The IEC 62305 standard series has to be observed. Particularly Supplement 5 to DIN EN 62305-3 provides detailed information on lightning and surge protection for PV systems. In addition, the CLC/TS 50539-12:2013 technical specification is available for Europe.
Q: Which lightning protection measures must be taken in PV systems?
A: A lightning protection system consists of external and internal lightning protection. External lightning protection includes air-termination systems and down conductors which discharge the lightning current via defined paths to the ground.
To ensure internal protection, it is recommended to use surge protective devices (SPDs) in all areas at risk.
Q: Which types of surge arresters are there?
A: Surge arresters are sub-divided into three classes: Type 1, 2 or 3. The arresters have a different discharge capacity and voltage protection level (max. voltage in case of a discharge process).
Q: How do I know which type of arrester to use?
A: This depends on whether an external lightning protection system is installed. If so, it depends on whether the separation distance between the lightning protection system and the PV components has been maintained (see WP018 and WP019).
Q: How are surge protective devices also distinguished?
A: In addition to the different types, we also distinguish between Red/Line and Yellow/Line.
Red/Line arresters include all types for the power side of a photovoltaic system. Yellow/Line arresters are used for signal and communication lines.
Q: Does an arrester have to be replaced after each discharge process?
A: No! DEHN surge arresters are capable of repeatedly discharging lightning currents. This was proven in several laboratory tests and is confirmed by our long-standing field experience.
Q: Do the modules of a PV system have to be earthed?
A: From a lightning protection point of view, it is not necessary to integrate the module frame in the earth-termination system. Only the mounting system must be integrated. However, certain module types have to be earthed. Observe the requirements of the module manufacturer.
Q: Is an additional earth-termination system required for a free field PV system with a pile-driven or screw-in foundation?
A: Yes! Although the foundations which are in contact with the ground fulfil the function of an earth electrode to a certain extent, a meshed earth-termination system is required to ensure lightning protection. Foundations in contact with the ground, however, can be used as earth-termination system. Detailed information on this topic can be found in Supplement 5 to DIN EN 62305-3.
