PV system SPD installation requirements without external lightning protection system

illustrate:

① Class II test SPD in accordance with IEC61643-31

② Class II test SPD in accordance with IEC61643-11

③ In accordance with IEC61643-11 Class I or Class II test SPD

④ Class II test SPD in accordance with IEC61643-31

Schematic diagram of Surge protection device installation of photovoltaic system without external lightning protection system

In general, two Surge protection devices should be installed on the DC side (positions ① and ④) and two SPDs (positions ③ and ②) should be installed on the AC side of the inverter as shown in Figure 1.

NOTE: When shielded DC cables are used, induced overvoltage protection is available at the interface of the equipment to which such cables are connected.

The Surge protection device in installation position ② is not required for the following cases:

1. The distance between the Surge protection device of the main power distribution cabinet and the inverter is less than 10m, and the PE wire is close to the AC wire. At this time, the SPD can only be installed in the main power distribution cabinet at position ③;

2. The inverter and the main power distribution cabinet are connected to the same grounding system, and the length of the Surge protection device connecting wires is less than or equal to 0.5m (for example, the inverter is located in the main power distribution cabinet).

The Surge protection device in installation location ④ is not required for the following cases:

1. The distance between the inverter and the photovoltaic array is less than 10m, and the voltage protection level (Up) of the Surge protection device installed in position 1 is less than or equal to 0.8 times the rated value of the surge voltage Uw of the photovoltaic array;

2. The voltage protection level (Up) of the SPD installed in position ① is less than or equal to 0.5 times the impulse withstand voltage rating Uw of the photovoltaic array, and the PE wire is close to the DC wire.

You can also continue to understand the following two situations：

1. The external lightning protection system meets the installation requirements of the surge protection device in the photovoltaic system with a safe distance.

2. Installation requirements for surge protection device in photovoltaic systems where the external lightning protection system does not meet the safety distance.