Lightning Protection Precautions for Industrial and Commercial Rooftop Photovoltaic Systems(2)

02 Be Sure to Ensure Grounding Reliability

01. The component grounding needs to be fully and reliable. The aluminum frame and bracket of the component are coated, and the grounding cannot be replaced by the crimping of the pressure block. Only the ground hole of the component is connected to the bracket through a 4mm² ground wire for effective grounding, and special attention should be paid to the plastic film of the aluminum alloy frame that needs to be completely removed before connection.

02. It is recommended to use round steel with a diameter greater than 8mm or flat steel with a thickness greater than 4mm for lightning protection grounding between supports and use welding instead of bolts to prevent corrosion or loosening due to a long time and ensure grounding reliability. At the same time, each row of brackets should select multiple points to use flat steel larger than 4mm to connect to the nearest lightning strip with the original lightning protection grounding system. If the building does not have a lightning protection grounding system, a lightning protection grounding system must be installed to ensure that the photovoltaic system is well-grounded.

03. The grounding resistance must meet the requirements: the grounding resistance of the lightning rod, the lightning strip, the down-conductor, the grounding body, etc. should be ≤10Ω; in addition, the grounding resistance of the protective grounding, working grounding, and shielding grounding should be ≤4Ω. When the inverter is independently grounded, it is recommended to use a copper grounding wire of no less than 10mm² to introduce a separate grounding body, and the grounding resistance is ≤4Ω.

The lightning protection and grounding of the photovoltaic system is one of the key guarantees for the long-term and effective operation of the entire power station. The photovoltaic system is struck by lightning, and the unreliable lightning protection system will cause the failure of components, inverters, and other electrical equipment.

At present, the lightning protection of photovoltaic systems generally adopts the method of system lightning protection and bridge lightning protection of buildings. Therefore, it is necessary to pay special attention to some key matters: pay special attention to the grounding of the inverter, it is recommended to do it separately; the lightning protection grounding construction process needs to fully guarantee the grounding reliability.

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