Installation of PV arrays at roof level, and the siting of solar parks in open, exposed locations, makes PV systems susceptible to damage from partial lightning currents.

Partial lightning currents can enter the PV system following a direct lightning strike to the external lightning protection system (LPS), or transient overvoltages from the wider electrical network.

Protecting the PV System
Effective protection against partial lightning currents can be achieved through installation of Surge Protective Devices (SPDs), on both the DC and AC sides of the DC-AC inverter.

The mains power SPDs selected should conform to BS EN 61643-11, and be installed in line with guidance in Technical Specification DD CLC/TS 50539-12;2010.

The appropriate SPD to protect each side of the inverter is dependent on wether the PV array is protected by an external LPS, and if so, wheter the minimum separation distance (to BS EN 62305-3) between the LPS and the metallic parts of the PV array has been kept.

To find out more on this subject download the Furse datasheet on the Protection of photovoltaic PV systems.

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