MET_Comm-FAIL and RS485 Fail Troubleshooting

The alarm "MET_Comm-FAIL" is given when the inverter does not detect the external Acrel meter and it is expecting to.

"RS584 Fail" will also show on the screen between the inverter and the meter. 

If no external Acrel meter is installed, then "No Meter" should be selected by following this path: Advanced Settings > password: down, down, up, enter > Storage Energy Set > Meter Select > down button to highlight "No Meter" then press enter

Please be aware that not installing an external Acrel meter will result in limitations for the system. The inverter relies on the meter and CTs to collect energy importation/exportation data. This means that the system will be unable to control how much energy is exported and the Self-Use mode will not work. 

Acrel sells many types of CTs and there are flexible CTs available for service panels where the main breaker has four cables or uses bars instead of cables. 

Troubleshooting "MET_Comm-FAIL"

  1. Check to ensure that 1Ph Meter is selected and not 3Ph Meter by following the path above
  2. If no Acrel is installed, then select No Meter and press Enter - the alarm should go away immediately
  3. From this step it is assumed that an Acrel meter is installed
  4. Check the communication wires between the inverter and the meter
    1. In the inverter, the pins "MTR485B" and "MTR485A" and "GND" are used for the meter communication wires
    2. MTR485B goes to B-     MTR485A goes to A+    GND goes to G
    3. Ensure that there is good contact between the wires and the terminal clamps by verifying that enough of the wire sheath has been removed - there must be a metal on metal contact 
    4. Ensure that the green terminal blocks on the Acrel are pushed in all the way
    5. On the Acrel, the right-most pin on the "RS485" block will not be used
  5. Verify that the meter is getting proper AC voltage on the bottom terminal block
    1. The Acrel meter requires 240Vac with a neutral - this is best provided with a "reference breaker" in the main service panel - pig tailing or double landing is not recommended but will work 
    2. Ensure that there is good contact between the wires and the terminal clamps
    3. If the meter is getting proper voltage, the lights should be on
  6. Double check that the CTs and the CT wires are installed properly
    1. Black wires from CTs are negative and red wires are positive
    2. The labels on the CTs should face towards the service panel and away from the utility meter
    3. The open CT has an arrow that should point in the opposite direction as the label on the CT. The arrow should point towards the utility meter and away from the service panel
    4. Ensure that there is good contact between the wires and the terminal clamps
  7. If all of this has been done and the inverter is still displaying "MET_Comm-FAIL" then the meter will need to be replaced. In the mean time, select "No Meter" so that the system will operate until the replacement arrives.

Victor is the author of this solution article.

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