This alarm will display if the inverter detects harmonic distortion on the AC-side of the system. The "INTF" is short for "interference" and the "GRID" means coming from the grid-side. Harmonic distortion can come a variety of sources, such as the grid, nonlinear electrical equipment, or the inverter itself. You must search for harmonic distortion using a Power Quality Analyzer. Please follow the steps to troubleshoot harmonic distortion on the AC side of the system:

  1. Turn the inverter at the site off through the Advanced Settings menu (Grid ON/OFF)
  2. Open the AC switch (or breaker) and then open the DC switch
  3. Set up a Power Quality Analyzer to measure THDa (current harmonics) on the AC cables
  4. Turn the inverter back on - DC first and then AC 
  5. After five minutes, the inverter should begin generating again
  6. Observe the harmonics and take a recording if your device allows you to
  7. If the harmonics are normal and the inverter is still displaying the alarm, contact Solis Support
  8. If the harmonics are abnormal, do the same thing to a nearby inverter for comparison
  9. If there is only one inverter at the site and the harmonics are abnormal, proceed with the next steps
    1. Note: Follow these steps if there are multiple inverters displaying the Grid-INTF alarm
  10. Turn the inverter(s) off: through Advanced Settings On/Off, then the AC switch, and then the DC switch
  11. Set up the Power Quality Analyzer in the load center (or where the breakers are) 
  12. Observe the THDa harmonics with no inverters generating
  13. If the harmonics are abnormal, then the cause is the grid or nearby nonlinear electrical equipment
  14. If the harmonics are normal, turn on one inverter (that has been displaying the alarm)
  15. Observe the harmonics as one inverter produces and exports power to the utility 
  16. If it seems as though the harmonic distortion is coming from the utility, recommend installing an EMI filter
  17. If the harmonic distortion appears to be caused by one inverter, contact Solis Support

Victor is the author of this solution article.

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