Lightning Protection Precautions for Industrial and Commercial Rooftop Photovoltaic Systems

01 Pay Special Attention to Inverter Lightning Protection Grounding

Commercial and commercial rooftop PV systems are often large in size, and cables often enter buildings and extend long distances to the grid connection point. While lightning can cause electrical disturbances based on induction and metal conduction, this effect increases with cable length or conductor loops. This can damage not only PV modules, inverters, and their monitoring electronics, but also equipment in building installations, so system lightning protection design is particularly important.

Typically, the building itself has a lightning protection grounding system. Therefore, the lightning protection grounding of most industrial and commercial photovoltaic systems will be connected to the building lightning protection through a flasher, and directly lead to the ground through the down conduct of the building lightning protection system.

This method is convenient for construction and low cost. It only needs to do the wiring of components lightning protection, bracket lightning protection, etc., and use the lightning protection grounding network of the building itself, which can prevent most lightning strikes, but it is necessary to pay special attention to inverter lightning protection. ground.

Through the on-site inspection and analysis of professional after-sales engineers, it is found that most of the projects with inverter failure caused by the lightning strike of the photovoltaic system have the following two situations:

01. The electrical ground of the inverter is directly connected with the building's flashing wiring, and the inverter is mostly installed in the surrounding projects.

02. The electrical grounding of the inverter is directly connected to the component bracket, and the inverter is mostly installed in the photovoltaic array.

Therefore, in the industrial and commercial photovoltaic system, the lightning protection grounding of the inverter must not share the ground with the roof lightning protection belt, and at the same time, the inverter and the lightning protection belt should maintain a certain safety distance. It is recommended to have a separate lead for the lightning protection grounding of the inverter, and the distance between the down conductor and the building lightning protection down conduct is recommended to be more than 10m.

In addition, it is not recommended to connect the casing ground and electrical ground of the inverter at the same time, and the casing ground of the inverter and the neutral ground of the power grid cannot be grounded together. Because when there is a ground fault on the grid side of the three-phase imbalance occurs, the high voltage of the neutral line to the ground will cause an electric shock to the operator through the casing.

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