Solar Earth Cable

Grounding in PV systems is one of the most frequently overlooked issues by PV installation personnel, especially in small-capacity PV systems where grounding and lightning protection are not given much attention.

However, if grounding is not done, errors can occur due to low insulation resistance to ground or excessive leakage currents, affecting power generation and potentially endangering personal safety. Additionally, unshielded or elevated metal parts are more susceptible to lightning strikes. Without grounding, equipment may be struck by lightning, causing significant damage to the PV power generation system.

Grounding in PV systems mainly includes grounding on the solar component side, inverter side, and distribution cabinet side. Proper grounding not only enhances the safety of the solar system but also extends its lifespan.

Generally, grounding holes on the solar panels are used to connect between strings of panels. The panels at both ends of the string are connected to the metal frame, primarily using yellow-green solar earth cables.

For grounding the panel frames, copper bonded steel rods of φ10 or φ12 are typically used, buried 1.5 meters underground.

The grounding resistance of solar panels should not exceed 4Ω. If the grounding resistance requirement is not met, resistance-reducing agents are usually added, or the grounding rods are buried in areas with lower soil resistivity.

Some people believe that since both the solar panels and their supporting structures are metal, grounding the supports alone is sufficient.

In reality, most solar panel aluminum frames and galvanized or aluminum alloy supports are coated, which does not meet grounding requirements. Additionally, solar panels can age over time, potentially leading to excessive leakage currents or low insulation resistance to ground. If the solar panel frames are not grounded, after a period of use, this can result in inverter failures, preventing the PV system from generating electricity properly.

When connecting solar panel frames to metal supports, it is necessary to remove the oxide layer from the metal surfaces to reduce grounding impedance, ensuring it meets grounding requirements.

Inverter Grounding: The grounding of the inverter is primarily achieved through the grounding wire of the AC cable and the grounding of the inverter’s casing. These measures help prevent errors in the PV inverter and ensure the stable operation of the system.

Distribution Cabinet Grounding: The grounding of the distribution cabinet is mainly to ensure the electrical safety of the entire system and the normal operation of the equipment. Specific grounding methods may include making a solid metal connection between the metal parts of the distribution cabinet and the grounding body.