Why protect a photovoltaic installation in buildings against overvoltages?

Photovoltaic (PV) installations in buildings are located on roofs, façades or other building structures. They may be domestic installations, intended for residential buildings, or industrial, designed to meet the energy needs of commercial buildings or industries.

Due to their atmospheric exposure, these systems are more susceptible to damage associated with the effects of lightning. To prevent such damage and subsequent financial and personal losses, lightning and overvoltage protection measures should be considered during the design phase.

Implementing this protection requires taking into account not only the general regulations for installing photovoltaic systems (IEC 60364-7-712), but also the instructions for selecting and installing SPDs (IEC 61643-32), on both the DC and AC sides.

The following aspects are relevant for the correct design and installation of SPDs in these systems:

• Characteristic data of supply systems, such as network configuration, nominal voltage and short-circuit current.
• Lightning protection class (LPL) required.
• Presence of an external lightning protection system and the number of external downpipe conductors.
• Clearance(s) to be maintained.
• Location of the inverter and cable lengths between the devices to be protected.