IVGM5-8K LP2G1 hybrid inverters (fault code list, solid fault LED); warning list uses 91 for push-button shutdown alarm
Felicity 91 error code
Parallel sync signal lost (solid LED): the parallel inverters lost their synchronisation signal; in the warning list the same number is the push-button shutdown alarm (flashing LED).
Likely causes
- Parallel synchronisation cable loose or damaged
- Master inverter offline or faulted
- Large configuration mismatch in the group
- The unit's shutdown button was pressed (warning variant)
Checks to run, in order
- 1Note whether the fault LED is solid (fault) or flashing (warning)
- 2Check the parallel communication and sync cables at every unit
- 3Confirm the master is powered and healthy
- 4If flashing, check whether the shutdown button was pressed
Fixes
- Reseat or replace the parallel sync cable
- Restore the master and restart the group
- For the warning, restart the unit after checking the button
When to escalate
If the sync wiring and master are healthy but code 91 persists, escalate for parallel-control service.
Fix it with the right tools
Check the system around the fault before replacing parts: load, battery bank, PV string and commissioning settings. If you need a second opinion, send the code and your inverter model to our team.
Before you open the inverter
- Isolate both the AC and DC sides, then confirm the display is dead before touching terminals.
- Use insulated tools and one hand where possible. DC arcs do not self-extinguish like AC.
- If you see burnt terminals, swollen cells, leaking electrolyte or a burning smell, stop and escalate instead of resetting the fault.
Questions installers ask
What does Felicity 91 mean?
Parallel sync signal lost (solid LED): the parallel inverters lost their synchronisation signal; in the warning list the same number is the push-button shutdown alarm (flashing LED).
How do I fix Felicity 91?
Reseat or replace the parallel sync cable Restore the master and restart the group For the warning, restart the unit after checking the button
When should I escalate Felicity 91?
If the sync wiring and master are healthy but code 91 persists, escalate for parallel-control service.
Can I reset Felicity 91 myself?
Only after isolating the AC and DC sides and running the checks above. If Felicity 91 returns immediately, stop resetting it and escalate; a repeating fault usually points to a real circuit, battery or hardware problem.
Which models show Felicity 91?
Felicity 91 is documented for IVGM5-8K LP2G1 hybrid inverters (fault code list, solid fault LED); warning list uses 91 for push-button shutdown alarm. Confirm the code on your own unit's display or manual before ordering parts.
More Felicity error codes
- Felicity 04Low cell voltage / over-discharge protection.
- Felicity 05PV over-current fault: the PV input current exceeded the inverter's PV input limit.
- Felicity 18PV short-circuit fault on the PV input; in the warning list the same number means battery under-voltage alarm.
- Felicity 19Battery open-circuit alarm: the inverter no longer detects a battery on its terminals.
- Felicity 20Battery SOC low alarm: the battery's state of charge has fallen to the low-SOC warning threshold.
- Felicity 21BMS communication alarm: abnormal communication between battery and inverter in non-SOC mode.
Guidance reviewed 17 October 2026 by the Mishka Energy installer team. Error codes vary by brand, model family and firmware; confirm against the manufacturer manual.
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