Photovoltaic systems with external lightning protection systems that meet the requirements of safe separation distances (including multiple grounded photovoltaic systems, such as photovoltaic power plants)
This is a better solution than if the safe separation distance (s) is not met. Compared to the third case, adopt measures to reduce the separation distance(s) requirements (such as the use of multiple or mesh down conductors), or use an external lightning protection system isolated from the installation (the photovoltaic system is part of the installation), is a better method.
The method of isolating the external lightning protection system from the protected device may only be used in the vicinity of the photovoltaic system (partially isolated lightning protection system).
① Class II test SPD in accordance with IEC61643-31
② Class II test SPD in accordance with IEC61643-11
③ Class I test SPD in accordance with IEC61643-11
④ Class II test SPD in accordance with IEC61643-31
⑤ Lightning protection system air-termination system
⑥ Lightning protection system down-conductor
Schematic diagram of Surge protective device installation when the photovoltaic system and external LPS meet the safety separation distance
Generally, two Surge protective devices should be installed on the DC side (positions ① and ④), and two SPDs should be installed on the AC side of the inverter (positions ③ and ②), as shown in Figure.
The Surge protective device in installation position ② is not required for the following cases:
1. The distance between the main distribution cabinet and the Surge protective device in the inverter is less than 10m, and the induced overvoltage caused by the lightning current flowing through the down conductor can be ignored (see IEC62305-4):
2. The length of the cables connected to the same grounding pole between the inverter and the main power distribution cabinet is less than or equal to 0.5m (for example, the inverter is located in the main power distribution cabinet).
The SPD 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 protective 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 Surge protective device 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.