IVGM5-8K LP2G1 hybrid inverters (fault code list, solid fault LED); warning list uses 18 for battery under-voltage alarm
Felicity 18 error code
PV short-circuit fault on the PV input; in the warning list the same number means battery under-voltage alarm.
Likely causes
- Damaged PV cable insulation or a pinched string cable
- Water in a PV connector or junction box
- Shorted PV string or reverse-connected string
- Conductive debris across the PV terminals
Checks to run, in order
- 1Note whether the fault LED is solid (fault) or flashing (warning) before acting
- 2Isolate the array and check for a short across the PV input
- 3Measure string voltages and inspect connectors for water or damage
- 4If the LED is flashing, read the battery voltage instead - code 18 is then a low-battery warning
Fixes
- Repair or replace the damaged PV cabling and connectors
- Dry and reseal wet connectors, then reconnect the array
- Restart 2-3 times and confirm the code clears
- For the flashing warning, charge the battery and check the low-voltage cutoff
When to escalate
If the PV input remains shorted with the array isolated, or the battery stays below the cutoff after a full charge, escalate to the distributor.
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 18 mean?
PV short-circuit fault on the PV input; in the warning list the same number means battery under-voltage alarm.
How do I fix Felicity 18?
Repair or replace the damaged PV cabling and connectors Dry and reseal wet connectors, then reconnect the array Restart 2-3 times and confirm the code clears For the flashing warning, charge the battery and check the low-voltage cutoff
When should I escalate Felicity 18?
If the PV input remains shorted with the array isolated, or the battery stays below the cutoff after a full charge, escalate to the distributor.
Can I reset Felicity 18 myself?
Only after isolating the AC and DC sides and running the checks above. If Felicity 18 returns immediately, stop resetting it and escalate; a repeating fault usually points to a real circuit, battery or hardware problem.
Which models show Felicity 18?
Felicity 18 is documented for IVGM5-8K LP2G1 hybrid inverters (fault code list, solid fault LED); warning list uses 18 for battery under-voltage 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 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.
- Felicity 22Battery under-voltage alarm or battery SOC low alarm: battery voltage is too low, or the BMS reports SOC too low, and the battery should be charged.
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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