Photovoltaic Relay Solution
The core requirements of the photovoltaic industry are high-voltage DC isolation, grid connection protection, fault interruption, and charge/discharge control. Relay applications must adapt to DC high-voltage environments above 1000V and harsh outdoor operating conditions.
Inverter DC Side
Core Requirements: High-voltage DC isolation and rapid fault interruption.
Main Types and Applications:
High-Voltage DC Power Relay:
Rated voltage up to 1000V DC or above.
Mainly used for electrical isolation between PV modules and the inverter, as well as rapid circuit interruption under fault conditions to prevent fault propagation.
Latching (Bi-Stable) Relay:
Utilizes its state-holding characteristic when de-energized, significantly reducing system standby power consumption, suitable for PV + energy storage systems.
Inverter AC Side
Core Requirements: Grid connection control and grid frequency protection.
Main Types and Applications:
AC Power Relay: Used to realize grid connection control between the PV system and the power grid.
Frequency Relay: Monitors grid frequency. When the frequency deviates from the normal range, it can quickly disconnect the grid connection circuit to achieve anti-islanding protection, ensuring the safety of the grid and the PV system.
Combiner Boxes and DC Distribution Cabinets
Core Requirements: Multi-string disconnection control and safe, arc-free interruption.
Main Types and Applications:
PV-Specific Power Relay:
Often employs a double-pole, double-throw (DPDT) configuration.
Utilizes positive and negative series interruption to effectively prevent arcing phenomena, enhancing interruption reliability.
Used for disconnection control of multiple PV strings.
PV + Storage System Charge/Discharge Control
Core Requirements: High-voltage switching control and system soft-start protection.
Main Types and Applications:
High-Voltage DC Relay: Used to achieve switching control between the battery bank and the inverter.
Pre-charge Relay and Resistor:
Used in conjunction with the main relay to achieve system soft-start.
Protects equipment from damage caused by high inrush currents.
Signal Monitoring and Control
Core Requirements: Precise signal switching and system noise immunity.
Main Types and Applications:
Reed Relay / Signal Isolation Relay:
Used for MPPT (Maximum Power Point Tracking) signal switching and electrical isolation of low-voltage control circuits.
Improves system control accuracy and anti-interference capability.
