Photovoltaic Grid-Connected Cabinet

Photovoltaic grid-connected cabinets play a crucial role in protection, metering, isolation, anti-islanding, and data exchange. They are designed and manufactured by the professional manufacturer Shangming. We offer a warranty and will provide complete documentation and certification with your order.

What Are the Functions of a Photovoltaic Grid-Connected Cabinet?

Power Collection: The PV grid-connected cabinet collects the AC power output from one or more string inverters.

Safety Isolation: When the grid is under maintenance or the PV system malfunctions, it physically disconnects the power supply via circuit breakers or disconnect switches, ensuring the safety of personnel and equipment.

Protection Functions: The PV grid-connected cabinet has protection against overcurrent, overvoltage, undervoltage, and frequency anomalies. Most importantly, it features anti-islanding protection, automatically disconnecting the grid connection point when the main grid fails to prevent reverse power transmission and potential electric shock to maintenance personnel.

Metering and Monitoring: The equipment has a built-in electricity meter, typically a bidirectional meter, recording both the electricity generated and consumed.

The Difference Between a Photovoltaic Grid-Connected Cabinet and a Photovoltaic Combiner Box

Installation Precautions

When installing a photovoltaic grid-connected cabinet, it should be installed as close as possible to the transformer or main distribution cabinet. Shorter cables result in less voltage drop. If the cable is too long, the voltage at the grid connection point will rise during peak power generation, triggering the inverter's overvoltage protection and causing frequent tripping.

For outdoor grid-connected boxes, installation in direct sunlight is strictly prohibited. High temperatures can cause the circuit breaker to thermally trip, leading to false tripping. We recommend choosing a location on the north wall of a building or installing a sunshade.

Please ensure that at least 800mm-1000mm of operating space is left in front of the cabinet to ensure that the operator can quickly turn the disconnect switch in an emergency.

FAQ

Q: Why does the circuit breaker in the grid-connected cabinet trip unexpectedly during peak power generation at noon?

A: Causes to be investigated:

Grid overvoltage: This is the most common cause. Solar power generation is strongest at noon, and if surrounding electricity consumption is low, the voltage at the grid connection point will be raised. When the voltage exceeds the protection limit set by the grid-connected cabinet, the cabinet will automatically trip.

Temperature tripping: Poor heat dissipation in the grid-connected cabinet. High current flow at noon causes the internal temperature of the cabinet to become too high, leading to malfunction of the circuit breaker's thermal protection.

Inappropriate setting: The circuit breaker's setting current is too close to the inverter's maximum output current.

Solutions: Check the voltage records. If the grid voltage is too high, contact the power supply bureau to lower the transformer tap or adjust the protection settings.

Q: What are the consequences if the surge protector in the grid-connected cabinet is faulty and not replaced?

A: It will not affect power generation in the short term, but it will lose lightning protection. Solar power plants are mostly located on open rooftops, where lightning induction is extremely frequent. In the event of induced lightning, high voltage can directly penetrate the grid-connected cabinet and enter the inverter, causing components worth hundreds of thousands of yuan to burn out.

We recommend that if the SPD status window turns red, it must be replaced immediately.

Q: Can a regular low-voltage distribution cabinet be used to replace the dedicated photovoltaic grid-connected cabinet?

A: No, it cannot be directly replaced. Regular distribution cabinets lack bidirectional metering, anti-islanding protection logic, and undervoltage tripping functionality.

The power supply bureau will focus on inspecting these photovoltaic-specific components during acceptance testing. If a forced replacement is made, the project will fail acceptance.