Inverter-to-battery communication

Inverter-to-battery communication enables real-time data exchange (voltage, current, State of Charge - SoC) via protocols like CAN bus or RS485 for safe, efficient charging. It establishes a closed-loop system, allowing the Battery Management System (BMS) to control the inverter, which protects lithium batteries from overcharging/discharging.

• Closed-Loop Communication (Active): The battery BMS directly tells the inverter maximum charge/discharge current, voltage limits, and SoC.
• Open-Loop Communication (Passive): The inverter estimates battery status based on voltage, which is less accurate for lithium batteries.
• Physical Connections: Usually RJ45 cables (CAN/RS485) connecting the battery's BMS to the inverter's BMS/COM port.
• Data Exchanged:
  • State of Charge (SoC): Accurate percentage of battery capacity remaining.
  • Voltage/Current Limits: Prevents overvoltage and overload.
  • Battery Temperature: Adjusts charging based on temperature.
• Required Configuration: The inverter must be set to the correct protocol (e.g., Pylontech, BYD) matching the battery to ensure communication.
• Benefits: Increased safety, improved battery lifespan, and optimized charging.

Common Communication Protocols & Ports

• CAN bus: Standard for many lithium batteries (e.g., SMA Solar).
• RS485: Common for smaller or specific hybrid systems (e.g., FelicityESS).

• State of Charge (SOC): Allows the inverter to show an accurate percentage rather than just guessing based on voltage.
• Safety Limits: The battery tells the inverter exactly how much current it can safely accept (charging) or provide (discharging) based on its current temperature and health.Automated Control: Enables features like automatic generator starting when the battery is low or stopping the discharge before reaching a critical level.

• CAN (Controller Area Network): A high-speed, robust protocol common in modern lithium systems.
• RS485: Often used for older or more basic communication setups.
• Closed-Loop vs. Open-Loop:
  • Closed-Loop: The inverter actively adjusts its behavior based on direct data from the battery.
  • Open-Loop (or No Communication): The inverter operates based on its own preset voltage settings without direct feedback from the battery.

Setup Requirements

1. Compatible Cable: Often a standard Ethernet cable (CAT5/6), though pin configurations must match the specific manufacturer's requirements.
2. Protocol Matching: Both the battery and inverter must be set to the same protocol (e.g., selecting "Pylontech" or "Deye" protocol in the inverter menu).