GoodWe Inverter BMS Communication Error Troubleshooting

Key Takeaways

• A BMS communication error means your GoodWe inverter cannot properly talk to your battery.
• Always start by checking the physical communication cable between the inverter and the battery.
• Verify the correct communication protocol (CAN or RS485) is selected in the inverter settings.
• If basic checks fail or internal faults persist, stop troubleshooting and contact a qualified technician.

What does a GoodWe BMS communication error mean?

A GoodWe inverter BMS communication error indicates that the inverter is unable to establish or maintain proper data exchange with your battery's Battery Management System (BMS). This communication is crucial for the inverter to monitor the battery's state of charge (SOC), voltage, temperature, and other parameters, allowing it to safely and efficiently manage charging and discharging. When communication fails, the battery may not charge, discharge, or the battery's internal switch may trip.

Diagnosis

Follow these steps to diagnose a GoodWe inverter BMS communication error.

1. Check the Inverter Display for Fault Codes:

• • Observation: The inverter display shows a specific fault code or message.
  • Meaning:
  • • If you see "BMS communications not OK" (commonly reported by installers for ET, A-ES, ES series), this directly points to a communication issue.
    • Code 31, "Internal Communication Failure", indicates a general internal communication problem within the inverter that could affect BMS communication.
    • Code 26, "Battery Licence Fault", means the battery activation code is incorrect.
    • If the display shows "Battery switch always trips (lithium battery)", this can be caused by "BMS communication fails".
  • Action: Note any specific codes or messages.

2. Inspect the BMS Communication Cable:

• • Observation: The physical cable connecting the inverter to the battery.
  • Meaning: A loose, damaged, or incorrect cable is a common cause of communication failure.
  • Action:
  • • Safety First: Before touching any connections, ensure all AC, PV, and battery power sources are disconnected. Wait at least 5 minutes after disconnecting all power before touching internal parts.
    • Visually inspect the communication cable between the GoodWe inverter's BMS Communication Port and the battery's communication port.
    • Ensure both ends are securely plugged in and not loose.
    • Check the cable for any visible damage, cuts, or corrosion.
    • Confirm the cable is the correct type for the communication protocol (e.g., RS485 or CAN).

3. Verify Communication Settings in the Inverter:

• • Observation: The inverter's settings for battery communication.
  • Meaning: Incorrect protocol selection prevents the inverter and battery from understanding each other.
  • Action:
  • • Access the inverter's settings via the display or the PV Master/SolarGo App.
    • Navigate to the battery settings section.
    • For ET Series, A-ES Series, and ES Series inverters, check the "Communication with BMS" setting. The options are typically RS485 or CAN. For ET and ES Series, CAN is the default. Ensure the selected protocol matches your battery's requirements.
    • For A-ES Series, the "Charging Strategy for Li-ion Battery" is "Self-adaption to BMS", meaning the inverter relies on the BMS for charge parameters.

4. Check Battery Status and Internal Switch:

• • Observation: The battery's own status indicators or internal breaker.
  • Meaning: The battery itself might be in a fault state or its internal protection has activated.
  • Action:
  • • Check the battery's display or LED indicators for any fault lights.
    • Ensure the battery's main power switch or circuit breaker is in the ON position.
    • If the battery switch has tripped, reset it according to the battery manufacturer's instructions. A tripped battery switch can be caused by "BMS communication fails" or "battery SOC too low".

5. Restart the Inverter:

• • Observation: The inverter's operational status after a power cycle.
  • Meaning: A simple restart can sometimes clear temporary communication glitches.
  • Action:
  • • Completely power down the GoodWe inverter by disconnecting AC, PV, and battery power in the correct sequence (usually AC first, then PV, then battery).
    • Wait for at least 5 minutes.
    • Power the inverter back on in the reverse sequence (battery first, then PV, then AC).

Cause/fix table section

Communication Protocol and Settings

GoodWe inverters, including the ET, A-ES, and ES series, communicate with lithium battery Battery Management Systems (BMS) using industry-standard protocols.

• Communication Protocols: GoodWe inverters support both RS485 and CAN communication protocols for BMS. For the ET Series and ES Series, CAN is typically the default protocol. You must ensure the inverter's setting matches the protocol used by your specific battery.
• Communication Ports:
• • ET Series inverters have a dedicated "BMS Communication Port".
  • A-ES Series inverters have a "BMS" port.
  • ES Series inverters feature both a "BMS Communication Port" and an "RS485 Communication Port".
• Cable Checks: Always use the correct communication cable provided by the battery manufacturer or specified by GoodWe. Pinouts can vary, so ensure the cable is designed for the specific inverter-battery pairing.
• Battery List: GoodWe manuals state to "Refer to PV Master/SolarGo App" for the list of compatible batteries. This app is where you would typically select your battery model, which then configures the appropriate communication settings and charge parameters.
• Firmware: Ensure your inverter's firmware is up to date. Sometimes, communication issues with newer battery models are resolved through firmware updates.

For more information on battery types and their management, you can refer to our general guide on solar batteries.

Safety

Working with solar inverters and batteries involves high voltages and stored energy. Always prioritize safety.

• Qualified Personnel Only: Installation, operation, and maintenance must be performed by qualified electricians.
• High Voltage/Electric Shock: There is a danger of high voltage and electric shock. Always wait at least 5 minutes after disconnecting all power sources (AC, PV, and battery) before touching internal parts of the inverter or battery connections.
• Unauthorized Modifications: Do not open the inverter cover or change components without the manufacturer's authorization. Doing so can void your warranty and poses a significant safety risk.
• Insulated Tools: When working with battery terminals or communication cables, use insulated tools to prevent accidental short circuits. A spanner across a battery bank can short hundreds of amps.
• Battery Breaker: For batteries without a built-in DC breaker, an external DC breaker is required. For ET series, this is ≥40A; for A-ES series, 70A; and for ES series, ≥125A.

When to call a technician instead

While many communication issues can be resolved with basic troubleshooting, there are clear limits to DIY repairs.

• Persistent Faults: If the BMS communication error persists after you have performed all the diagnostic steps, including checking cables, verifying settings, and restarting the inverter.
• Internal Communication Failure (Code 31): If the inverter repeatedly displays "Internal Communication Failure", this suggests a deeper internal issue that requires professional diagnosis.
• Battery Licence Fault (Code 26): This specific error requires contacting the service center as it relates to battery activation or compatibility.
• Uncertainty: If you are unsure about any step or uncomfortable working with high-voltage electrical equipment, do not proceed.
• Warranty Concerns: Any unauthorized opening of the inverter or modifications can invalidate your warranty. Contacting a qualified technician ensures that repairs are performed correctly and maintain warranty coverage.