The PV system diagram consists of two parts - the AC side and the DC side. There is an inverter between these parts, which is the center piece of the system and its function is to convert the DC power generated by the PV modules into AC power that can be supplied to the distribution system or consumed as part of an autonomous system. The standard HD 60364-7-712:2016 requires the installation of surge protection devices on both the DC and AC side. The EN 50539-12 or the new EN 61643-32 standard helps us to choose the right type of surge protection device.
For conventional PV panels, we can assume that their impulse withstand voltage UW is higher than the inverter's
UW. In this case, we recommend installing the SPD as close as possible to the inverter. This only applies
when the distance between the inverter and the PV modules is less than 10 m. Otherwise, it is necessary
to install two SPDs on both sides of the DC line, i.e. both at the inverter and at the PV modules. As
to the DC side, the condition of the inverter's distance from the main switchboard applies to the AC side.
If the inverter is installed in the distance less than 10 m of cable line from the main switchboard, it
is sufficient to install the SPD only in the main switchboard, where it is always installed, unless the
risk management calculation specifies otherwise. If the distance is longer, the SPD shall also be installed
as close as possible to the inverter.
The type of SPD we install is determined by two conditions. The first is whether the building has an external
lightning protection system (LPS). In other words, if it has an air termination system. The second condition
is the compliance with the separation distance "s" between the supporting structure of the PV modules
or between the modules themselves and the air termination system.
The selection of the SPD continuous operating voltage (UC) on the DC side is derived from the no-load
voltage value of the PV generator under standard test conditions (UOC STC). The minimum UC value shall
be greater than or equal to 1,2 times of the UOC STC value.
Hakel has introduced a new range of G-line surge arresters for PV installations to complement its core
range. It offers both SPDs type T2 and T1+T2 in both U and Y connection for all LPL levels, i.e. for all
possible applications. All that for voltage levels from 600 V DC to 1 500 V DC. In addition, they guarantee
zero discharge or leakage currents in the Y connection, which can trigger the reaction of insulation monitoring
device, which every IT power supply system must be equipped with.
It is also important to note that in today's world of modern information technologies, there are devices
in these applications that need to be protected by special surge protection devices for the transmission
of data and information signals. Find out more in the Data
protection product catalogue