IVGM5-8K LP2G1 hybrid inverters (fault code list, solid fault LED)
Felicity 78 error code
Grid wrongly connected to the backup port: grid voltage is present on the backup (load) terminals.
Likely causes
- Utility supply landed on the backup terminals instead of the grid terminals
- Swapped GRID and LOAD wiring during installation
- Parallel system miswired
- Backfeed from another AC source on the backup circuit
Checks to run, in order
- 1Confirm which terminals carry the utility supply and which feed the backup loads
- 2Measure voltage on the GRID and LOAD terminals with the inverter isolated
- 3Check the installation drawing against the wiring
- 4Inspect for a second AC source feeding the backup circuit
Fixes
- Rewire the utility supply to the GRID terminals and the loads to the LOAD terminals
- Remove any backfeed source from the backup circuit
- Restart and confirm the code clears
When to escalate
If the wiring is correct and code 78 persists, the inverter's grid/backup detection circuit needs distributor 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 78 mean?
Grid wrongly connected to the backup port: grid voltage is present on the backup (load) terminals.
How do I fix Felicity 78?
Rewire the utility supply to the GRID terminals and the loads to the LOAD terminals Remove any backfeed source from the backup circuit Restart and confirm the code clears
When should I escalate Felicity 78?
If the wiring is correct and code 78 persists, the inverter's grid/backup detection circuit needs distributor service.
Can I reset Felicity 78 myself?
Only after isolating the AC and DC sides and running the checks above. If Felicity 78 returns immediately, stop resetting it and escalate; a repeating fault usually points to a real circuit, battery or hardware problem.
Which models show Felicity 78?
Felicity 78 is documented for IVGM5-8K LP2G1 hybrid inverters (fault code list, solid fault LED). 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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