Is surge protection required for photovoltaic systems?

The DIN VDE 0100-443 and -534 standards stipulate the installation of surge protection devices in low-voltage networks to prevent damage. However, these regulations only refer to the need for surge protection on the alternating current side. For comprehensive protection of photovoltaic systems, their operators and the residents of houses, it is advisable to also consult DIN VDE 0100-712. This standard enables the development of a holistic protection concept that also covers the direct current range.

The DIN VDE 0100-443 and -534 standards play a decisive role in the protection of buildings and their occupants. However, it should be noted that these standards primarily address surge protection on the AC side and do not offer comprehensive protection. Their main purpose is to minimize the risk of fire, which is essential, but does not cover all risks.

For example, photovoltaic systems (PV systems) do not increase the risk of lightning strikes, but require adequate safety measures to protect people, technology and buildings. DIN VDE 0100-712, which has been available in a new version since April 2019, is important here. This standard specifies lightning and surge protection for PV power supply systems and refers to DIN VDE 0185-305-3 Supplement 5, which prescribes surge protection on the DC side.

A detailed understanding of the standard and Supplement 5 of DIN EN 62305-3 is important for the development of a comprehensive protection concept. They provide guidance for the risk assessment and selection of suitable surge protective devices (SPDs).

The selection of suitable protective measures and surge protective devices (SPDs) for specific installations is a crucial step. The standard describes three different scenarios, each with specific parameters, and recommends suitable measures.

For photovoltaic systems (PV systems) without lightning protection, type 2 SPDs are recommended on the alternating current (AC) and direct current (DC) side. For PV systems with external lightning protection, it is necessary to maintain a minimum distance between the lightning conductor and the frame of the PV modules, as described in the DIN EN 62305-3 standard. In addition, a type 1 lightning arrester, such as a “Raycap ProTec ZPS”, must be installed at the AC building entry, supplemented by type 2 SPDs around the inverter. In the third scenario, if the required separation distance is not met and the PV frame is integrated into the lightning protection system, Type 1 SPDs are required both at the building entrance and around the inverter if the distance is more than 10 meters.

Installers and solar technicians should adhere to these recommendations. According to DIN VDE 0100-712, appropriate protection is also required on the DC side of the PV system in the event of transient overvoltages in accordance with DIN VDE 0100-443 section 443. DIN VDE 0100-443 hardly leaves out any building type, which makes these measures almost a general obligation.