What is the difference between a fault and a warning on the T-REX-50KHP3G01?

A fault cuts the unit's output and the red LED stays solid — this page lists 105 of them for the T-REX-50KHP3G01. The T-REX-50KHP3G01 manual defines no separate warning table — every listed code stops operation. Resolve the cause of a fault before restarting; warnings can usually be cleared while the unit runs.

Does this page apply to other Felicity models?

No — this table was transcribed specifically from the T-REX-50KHP3G01 manual. Other Felicity devices have their own pages; start from the error-code hub to find the one matching the model number on your unit's label.

Where do these codes come from?

Every entry was transcribed from T-REX-50KHP3G01-user-manual-.pdf — Felicity's official documentation. Each row cites its source manual (and page where printed), so you can verify the wording before acting on it.

Felicity T-REX-50KHP3G01 Error Codes: Causes & Fixes (105 codes)

This is the complete fault table for the Felicity T-REX-50KHP3G01 Inverter — all 105 codes from the official manual on one page. On Felicity units, a fault code means the unit has cut its output and the red LED stays solid; a warning flashes the red LED while the unit keeps running.

Last checked against the official manuals on July 10, 2026.

Fault(105)— output stops · red LED solid

Fault codes (105)output stops · red LED solid

F01

PV1 overvoltage fault.

Fault

The voltage of the PV1 is too high, check the voltage of the string.

CauseThe open-circuit voltage of the PV1 string is above the inverter's permitted DC input range — typically a string configured with too many modules in series.

Recommended fixPower down the inverter, wait 5 minutes for capacitors to discharge, then restart. If the fault recurs immediately or repeatedly, record the exact code and contact your installer or the manufacturer's service line.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 45

F02

PV2 overvoltage fault.

Fault

The voltage of the PV2 is too high, check the voltage of the string.

CauseThe open-circuit voltage of the PV2 string is above the inverter's permitted DC input range — typically a string configured with too many modules in series.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 45

F03

PV3 overvoltage fault.

Fault

The voltage of the PV3 is too high, check the voltage of the string.

CauseThe open-circuit voltage of the PV3 string is above the inverter's permitted DC input range — typically a string configured with too many modules in series.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 45

F04

PV4 overvoltage fault.

Fault

The voltage of the PV4 is too high, check the voltage of the string.

CauseThe open-circuit voltage of the PV4 string is above the inverter's permitted DC input range — typically a string configured with too many modules in series.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 45

F05

PV1 overcurrent fault.

Fault

The current of the PV1 is too large, check the string current.

CauseCurrent from the PV1 string exceeded the input stage's protection limit — more current than that MPPT channel is rated to carry.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 45

F06

PV2 overcurrent fault.

Fault

The current of the PV2 is too large, check the string current.

CauseCurrent from the PV2 string exceeded the input stage's protection limit — more current than that MPPT channel is rated to carry.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 45

F07

PV3 overcurrent fault.

Fault

The current of the PV3 is too large, check the string current.

CauseCurrent from the PV3 string exceeded the input stage's protection limit — more current than that MPPT channel is rated to carry.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 45

F08

PV4 overcurrent fault.

Fault

The current of the PV3 string is too large, check the string current.

CauseCurrent from the PV4 string exceeded the input stage's protection limit — more current than that MPPT channel is rated to carry.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 45

F09

PV1 reverse connection fault.

Fault

Pv1 string positive and negative connection, check the string wiring.

CauseThe PV1 string is connected with positive and negative reversed, so the input stage blocks it until the string wiring is corrected.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 45

F10

PV2 reverse connection fault.

Fault

Pv2 string positive and negative connection, check the string wiring.

CauseThe PV2 string is connected with positive and negative reversed, so the input stage blocks it until the string wiring is corrected.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 45

F11

PV3 reverse connection fault.

Fault

Pv3 string positive and negative connection, check the string wiring.

CauseThe PV3 string is connected with positive and negative reversed, so the input stage blocks it until the string wiring is corrected.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 46

F12

PV4 reverse connection fault.

Fault

Pv4 string positive and negative connection, check the string wiring.

CauseThe PV4 string is connected with positive and negative reversed, so the input stage blocks it until the string wiring is corrected.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 46

F14

Battery 1 software overvoltage fault.

Fault

Battery 1 voltage is too high, the battery should be discharged.

CauseThe control firmware measured battery 1 voltage above the protection limit — the pack is overcharged or its configuration exceeds the inverter's battery range, and it should be discharged.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 46

F15

Battery 2 software overvoltage fault.

Fault

Battery 2 voltage is too high, the battery should be discharged.

CauseThe control firmware measured battery 2 voltage above the protection limit — the pack is overcharged or its configuration exceeds the inverter's battery range, and it should be discharged.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 46

F16

Battery 1 Overvoltage fault.

Fault

Battery 1 voltage is too high, the battery should be discharged.

CauseBattery 1 voltage tripped the hardware overvoltage protection, which acts independently of the firmware — the pack is above the permitted range and should be discharged.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 46

F17

Battery 2 Overvoltage fault.

Fault

Battery 2 voltage is too high, the battery should be discharged.

CauseBattery 2 voltage tripped the hardware overvoltage protection, which acts independently of the firmware — the pack is above the permitted range and should be discharged.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 46

F18

Battery 1 Undervoltage fault.

Fault

Battery 1 voltage is too low, the battery should be charged.

CauseBattery 1 voltage has fallen below the permitted range — the pack is deeply discharged and must be charged before normal operation resumes.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 46

F19

Battery 2 Undervoltage fault.

Fault

Battery 2 voltage is too low, the battery should be charged.

CauseBattery 2 voltage has fallen below the permitted range — the pack is deeply discharged and must be charged before normal operation resumes.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 46

F20

Battery 1 software overcurrent fault.

Fault

Battery 1 current is too large, check the battery charge and discharge power.

CauseThe control firmware measured battery 1 current above the protection limit — charge or discharge power beyond what that battery channel is rated for.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 46

F21

Battery 2 software overcurrent fault.

Fault

Battery 2 current is too large, check the battery charge and discharge power.

CauseThe control firmware measured battery 2 current above the protection limit — charge or discharge power beyond what that battery channel is rated for.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 46

F22

Battery 1 overcurrent fault.

Fault

Battery 1 current is too large, check the battery charge and discharge power.

CauseBattery 1 current tripped the hardware overcurrent protection, which acts independently of the firmware — a fast surge in charge or discharge current on that channel.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 46

F23

Battery 2 overcurrent fault.

Fault

Battery 2 current is too large, check the battery charge and discharge power.

CauseBattery 2 current tripped the hardware overcurrent protection, which acts independently of the firmware — a fast surge in charge or discharge current on that channel.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 46

F24

Battery 1 reverse connection fault.

Fault

Battery 1 positive and negative poles is reversed, check the battery wiring.

CauseBattery 1 is connected with positive and negative poles reversed, so the battery stage blocks it until the wiring is corrected.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 46

F25

Battery 2 reverse connection fault.

Fault

Battery 2 positive and negative poles is reversed, check the battery wiring.

CauseBattery 2 is connected with positive and negative poles reversed, so the battery stage blocks it until the wiring is corrected.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 46

F26

Battery 1 relay open circuit fault.

Fault

Battery 1 relay not closing properly causing open circuit, shutdown and restart.

CauseA safety relay inside the inverter has failed self-test or is stuck. The inverter is designed to refuse grid connection in this state, so this is not an issue you can clear with restart cycles.

Recommended fixThis requires service — the relay assembly is not user-replaceable. Record the exact fault code and contact your installer or the manufacturer's service line. Do not bypass any safety interlock.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 46

F27

Battery 2 relay open circuit fault.

Fault

Battery 2 relay not closing properly causing open circuit, shutdown and restart.

CauseA safety relay inside the inverter has failed self-test or is stuck. The inverter is designed to refuse grid connection in this state, so this is not an issue you can clear with restart cycles.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 46

F28

Battery 1 relay short circuit fault.

Fault

Battery 1 relay not properly disconnected causing short circuit, shutdown and restart.

CauseA safety relay inside the inverter has failed self-test or is stuck. The inverter is designed to refuse grid connection in this state, so this is not an issue you can clear with restart cycles.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 46

F29

Battery 2 relay short circuit fault.

Fault

Battery 2 relay not properly disconnected causing short circuit, shutdown and restart.

CauseA safety relay inside the inverter has failed self-test or is stuck. The inverter is designed to refuse grid connection in this state, so this is not an issue you can clear with restart cycles.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 46

F30

Battery 1 soft start fault.

Fault

Battery 1 fails to raise the input voltage normally, shutdown and restart.

CauseBattery 1's input stage failed to raise its voltage to the working point during the soft-start ramp — an internal converter fault on that channel.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 46

F31

Battery 2 soft start fault.

Fault

Battery 2 fails to raise the input voltage normally, shutdown and restart.

CauseBattery 2's input stage failed to raise its voltage to the working point during the soft-start ramp — an internal converter fault on that channel.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 46

F32

Battery 1 SOC Low fault.

Fault

Battery 1 SOC is too low, the battery should be charged.

CauseBattery 1's state of charge has dropped below the protection threshold — the pack has too little usable energy left and must be charged.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 46

F33

Battery 2 SOC Low fault.

Fault

Battery 2 SOC is too low, the battery should be charged.

CauseBattery 2's state of charge has dropped below the protection threshold — the pack has too little usable energy left and must be charged.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 46

F35

Bus software overvoltage fault.

Fault

Bus voltage is too high, shutdown and restart.

CauseThe control firmware measured the internal DC bus above its protection ceiling — a regulation fault in the conversion stages or a surge fed in from the PV or AC side.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 46

F36

Bus overvoltage fault.

Fault

Bus voltage is too high, shutdown and restart.

CauseThe internal DC bus tripped the hardware overvoltage protection, which acts independently of the firmware — a fast bus-voltage spike beyond the protection ceiling.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 47

F37

Bus undervoltage fault.

Fault

Bus voltage is too low, shutdown and restart.

CauseThe internal DC bus voltage fell below its operating range. The bus is regulated entirely inside the unit, so a persistent low reading points to an internal conversion-stage fault.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 47

F38

Positive and negative bus imbalance fault.

Fault

Positive bus voltage does not match negative bus voltage, shutdown and restart.

CauseThe positive and negative halves of the internal DC bus no longer match in voltage — an internal balancing fault in the conversion stages.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 47

F39

Bus soft start fault.

Fault

Bus voltage fails to rise normally at startup, shutdown and restart.

CauseThe DC bus failed to rise to its working voltage during the startup soft-start ramp — an internal converter or pre-charge fault.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 47

F40

Bus short circuit fault.

Fault

Bus short, shut down and restart.

CauseA short circuit was detected on the internal DC bus — bus voltage collapsed while current spiked, which is an internal power-stage fault.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 47

F41

Balanced Bridge Software Overcurrent Fault.

Fault

Balanced bridge current is too high, shutdown and restart.

CauseThe control firmware measured current in the bus-balancing bridge above its protection limit — the circuit that keeps the two bus halves matched is overloaded or faulty.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 47

F42

Balanced Bridge Overcurrent Fault.

Fault

Balanced bridge current is too high, shutdown and restart.

CauseCurrent in the bus-balancing bridge tripped the hardware overcurrent protection, which acts independently of the firmware — a fast current spike in the circuit that keeps the two bus halves matched.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 47

F44

Inverter soft start fault.

Fault

Inverter voltage fails to rise normally at startup, shutdown and restart.

CauseThe inverter stage failed to raise its output voltage to the working point during the startup soft-start ramp — an internal fault rather than a wiring issue.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 47

F45

Inverter voltage fault.

Fault

Inverter voltage is too high, shutdown and restart.

CauseThe inverter stage's output voltage ran above the permitted range — an internal regulation fault rather than a wiring issue.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 47

F46

Inverter software overcurrent fault.

Fault

Inverter current is too high, check the given power and load size.

CauseThe control firmware measured inverter output current above its protection limit — the commanded power or the connected load is beyond what the unit can deliver.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 47

F47

Inverter overcurrent fault.

Fault

Inverter current is too high, check the given power and load size.

CauseInverter output current tripped the hardware overcurrent protection, which acts independently of the firmware — a fast surge from the load side or a fault in the output stage.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 47

F48

Inverter short circuit fault.

Fault

Short circuit at inverter, shutdown and restart.

CauseA short circuit was detected at the inverter output: current spiked while voltage collapsed, pointing to a wiring fault or a shorted load.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 47

F49

Inverter voltage DC component fault.

Fault

Inverter voltage DC component is too high, shutdown and restart.

CauseA DC offset beyond the permitted limit was detected riding on the inverter's output voltage — the output stage is no longer producing a symmetrical sine wave.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 47

F50

Inverter current DC component fault.

Fault

Inverter current DC component is too high, shutdown and restart.

CauseA DC component beyond the permitted limit was detected in the inverter's output current — the output waveform has developed an asymmetry the unit is not allowed to feed to loads or the grid.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 47

F51

Grid Overvoltage Fault.

Fault

The grid voltage is too high, check whether the grid voltage is within the normal range.

CauseThe grid voltage measured at the AC terminals is above the inverter's permitted operating window, so it disconnects until the grid returns to range.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 47

F52

Grid Undervoltage Fault.

Fault

The grid voltage is too low, check whether the grid voltage is within the normal range.

CauseThe grid voltage measured at the AC terminals is below the inverter's permitted operating window, so it disconnects until the grid recovers.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 47

F53

Grid Over-frequency Fault.

Fault

The grid frequency is too high, check whether the grid frequency is within the normal range.

CauseThe grid frequency is above the inverter's permitted operating window, so it disconnects until the frequency settles back into range.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 47

F54

Grid Underfrequency Fault.

Fault

The grid frequency is too low, check whether the grid frequency is within the normal range.

CauseThe grid frequency is below the inverter's permitted operating window, so it disconnects until the frequency recovers.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 47

F55

Grid Reverse Sequence Fault.

Fault

The grid phase sequence is reversed, check the grid phase sequence wiring.

CauseThe grid phase sequence at the AC terminals is reversed relative to what the inverter expects, so it cannot synchronise until the phase wiring order is corrected.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 47

F56

Grid Overload Fault.

Fault

The load of the grid access is too large, and the load should be reduced.

CauseThe load drawn through the grid connection exceeds the permitted level, so the inverter trips until the load is reduced.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 47

F57

Active Islanding Fault.

Fault

The inverter enters active islanding.

CauseGrid power was lost and the inverter's active islanding protection tripped — it detected it was about to energise a dead grid section on its own and disconnected.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 47

F58

Grid Imbalance Fault.

Fault

Grid three-phase voltage unbalance, check the grid three-phase voltage.

CauseThe three grid phase voltages are unequal beyond the permitted tolerance, so the inverter cannot run balanced grid-tied operation until the phase voltages are corrected.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 47

F59

Load overload 110% Fault.

Fault

The load exceeds 110%, the load should be reduced.

CauseThe connected load has exceeded 110% of the inverter's rated output — the first overload tier; the load must be reduced.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 47

F60

Load overload 125% Fault.

Fault

The load exceeds 125%, the load should be reduced.

CauseThe connected load has exceeded 125% of the inverter's rated output — a deeper overload tier that trips faster than the 110% level; the load must be reduced.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 48

F61

Load overload 150% Fault.

Fault

The load exceeds 150%, the load should be reduced.

CauseThe connected load has exceeded 150% of the inverter's rated output — a severe overload tier; protection cuts the output until the load is reduced.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 48

F62

Load overload 200% Fault.

Fault

The load exceeds 200%, the load should be reduced.

CauseThe connected load has exceeded 200% of the inverter's rated output — the deepest overload tier, treated as a near-short; protection cuts the output immediately.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 48

F63

EPO Fault.

Fault

Inverter emergency shutdown.

CauseThe emergency power off (EPO) input was triggered, commanding an immediate inverter shutdown.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 48

F64

IGBT over-temperature fault.

Fault

Inverter device temperature is too high.

CauseThe power-stage IGBT temperature exceeded its protection limit — sustained high load, high ambient temperature, or restricted cooling.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 48

F65

Ambient Overtemperature.

Fault

The ambient temperature of the inverter is too high.

CauseInverter internal temperature has exceeded the safe operating threshold. Causes include high ambient temperature, blocked cooling vents, failed cooling fan, or installation in direct sunlight.

Recommended fixPower down the inverter and let it cool. Inspect cooling vents and fan inlets for dust, leaves, or insect nests — clean with compressed air. Confirm the inverter is installed in a shaded, ventilated location with the manufacturer's required clearances on all sides. If the fan does not spin on restart, fan replacement is required.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 48

F66

Fan 1 Fault.

Fault

Fan 1 is faulty, check whether the fan is normal.

CauseInternal cooling fan failure detected. Often caused by dust buildup, bearing wear, or debris fouling the fan blades.

Recommended fixPower down the inverter and remove the cover (only if the unit is field-serviceable per the manual). Inspect the fan for debris and clean. If the fan does not spin freely or is noisy, replace it with the manufacturer's OEM part.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 48

F67

Fan 2 Fault.

Fault

Fan 2 is faulty, check whether the fan is normal.

CauseInternal cooling fan failure detected. Often caused by dust buildup, bearing wear, or debris fouling the fan blades.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 48

F68

Fan 3 Fault.

Fault

Fan 3 is faulty, check whether the fan is normal.

CauseInternal cooling fan failure detected. Often caused by dust buildup, bearing wear, or debris fouling the fan blades.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 48

F69

Fan 4 Fault.

Fault

Fan 4 is faulty, check whether the fan is normal.

CauseInternal cooling fan failure detected. Often caused by dust buildup, bearing wear, or debris fouling the fan blades.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 48

F70

Internal fan fault.

Fault

Internal fan is faulty, check internal fan for is normal.

CauseInternal cooling fan failure detected. Often caused by dust buildup, bearing wear, or debris fouling the fan blades.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 48

F71

EEPROM Fault.

Fault

There was an error with the EEPROM write.

CauseA write error occurred in the EEPROM that stores the inverter's settings and calibration, so the control board cannot reliably save or recall its configuration.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 48

F72

12V auxiliary power supply fault.

Fault

Failure of 12V auxiliary power supply.

CauseThe internal 12 V auxiliary supply that powers the control and driver circuits has failed, so the inverter cannot keep its own electronics running reliably.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 48

F73

CT or Hall open circuit fault.

Fault

Current sensing device is faulty, check CT or Hall element connections.

CauseA current-sensing device (CT or Hall-effect sensor) reads open circuit — one of the inverter's current measurement paths is broken, so protection can no longer rely on it.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 48

F74

Main and auxiliary DSP communication fault.

Fault

There is an error in the DSP communication, try to upgrade the software.

CauseCommunication has been lost between the inverter and a peripheral device — typically a battery BMS, smart meter, or external monitoring dongle.

Recommended fixVerify the communication cable (CAN/RS485/Modbus) is correctly seated and the right pinout is used. Check baud rate and protocol settings in both devices match. Reseat the dongle/comms module. For BMS comms, confirm the battery is powered on and not in deep-discharge protection.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 48

F75

MCU Communication Fault.

Fault

There is an error in the MCU communication, try to upgrade the software.

CauseCommunication has been lost between the inverter and a peripheral device — typically a battery BMS, smart meter, or external monitoring dongle.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 48

F76

Leakage current fault.

Fault

The leakage current of the inverter is too large, check the wiring of the inverter.

CauseLeakage current to ground exceeded the safety limit — insulation or wiring on the DC or AC side is letting current return outside the normal conductors.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 48

F77

PV Insulation Impedance fault.

Fault

The insulation of the PV string is abnormal.

CauseA fault has been detected in the PV input stage — usually a short, ground fault, or isolation failure between the PV array and the inverter chassis. Wet connectors, damaged cable insulation, or moisture in a junction box are common causes.

Recommended fixDisconnect the PV strings and measure insulation resistance between PV+ and ground, PV- and ground, and PV+ to PV-. Any resistance below 1 MΩ indicates moisture or damaged insulation. Inspect MC4 connectors for water ingress. Reconnect each string one at a time to isolate the faulty string.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 48

F78

BAT1 Insulation Impedance fault.

Fault

Battery 1 insulation is abnormal.

CauseThe insulation between the battery 1 circuit and ground measured below the safe threshold — damaged cable insulation or moisture in that battery's wiring.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 48

F79

BAT2 Insulation Impedance.

Fault

Battery 2 insulation is abnormal.

CauseThe insulation between the battery 2 circuit and ground measured below the safe threshold — damaged cable insulation or moisture in that battery's wiring.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 48

F83

Inverter relay open circuit fault.

Fault

Inverter relay not closing properly causing open circuit, shutdown and restart.

CauseA safety relay inside the inverter has failed self-test or is stuck. The inverter is designed to refuse grid connection in this state, so this is not an issue you can clear with restart cycles.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 48

F84

Short circuit fault of inverter relay.

Fault

Inverter relay not properly disconnected causing short circuit, shutdown and restart.

CauseA safety relay inside the inverter has failed self-test or is stuck. The inverter is designed to refuse grid connection in this state, so this is not an issue you can clear with restart cycles.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 48

F87

Parallel CAN communication.

Fault

The inverter is connected to abnormal parallel communication.

CauseCommunication has been lost between the inverter and a peripheral device — typically a battery BMS, smart meter, or external monitoring dongle.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 48

F88

Parallel host loss fault.

Fault

Parallel host disconnects from the system, check whether the hosts is normal.

CauseThe parallel host (master) inverter has disconnected from the system, so the group has lost its coordinating unit until the host is restored.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 49

F91

PV hardware overcurrent fault.

Fault

PV current is too high, check string current.

CauseThe PV input's hardware overcurrent protection tripped — string current spiked above the trip threshold faster than the software limit reacts.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 49

F92

BMS1 communication failure.

Fault

BMS1 fails to communicate normally, check the BMS1 communication cable.

CauseCommunication has been lost between the inverter and a peripheral device — typically a battery BMS, smart meter, or external monitoring dongle.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 49

F93

BMS2 communication failure.

Fault

BMS2 fails to communicate normally, check the BMS2 communication cable.

CauseCommunication has been lost between the inverter and a peripheral device — typically a battery BMS, smart meter, or external monitoring dongle.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 49

F94

PV side busbar rapid overvoltage.

Fault

Bus voltage too high, shutdown and restart.

CauseThe PV-side DC bus voltage rose above its protection ceiling too quickly for normal regulation to respond — a fast transient overvoltage rather than a slow drift.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 49

W01

Battery 1 overvoltage alarm.

Fault

Battery 1 voltage is too high and the battery should be discharged.

CauseBattery 1 voltage has climbed to the overvoltage alarm threshold — the warning stage before the overvoltage fault; the pack should be discharged.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 44

W02

Battery 2 overvoltage alarm.

Fault

Battery 2 voltage is too high and the battery should be discharged.

CauseBattery 2 voltage has climbed to the overvoltage alarm threshold — the warning stage before the overvoltage fault; the pack should be discharged.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 44

W03

Battery 1 undervoltage alarm.

Fault

Battery 1 voltage is too low, the battery should be charged.

CauseBattery 1 voltage has fallen to the undervoltage alarm threshold — the warning stage before the undervoltage fault; the pack should be charged.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 44

W04

Battery 2 undervoltage alarm.

Fault

Battery 2 voltage is too low, the battery should be charged.

CauseBattery 2 voltage has fallen to the undervoltage alarm threshold — the warning stage before the undervoltage fault; the pack should be charged.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 44

W05

Battery 1 SOC low alarm.

Fault

Battery 1 SOC is too low, the battery should be charged.

CauseBattery 1's state of charge has dropped to the low-SOC alarm threshold — little usable energy remains and the pack should be charged.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 44

W06

Battery 2 SOC low alarm.

Fault

Battery 2 SOC is too low, the battery should be charged.

CauseBattery 2's state of charge has dropped to the low-SOC alarm threshold — little usable energy remains and the pack should be charged.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 44

W07

High voltage ride through alarm.

Fault

Entering high voltage ride-through at grid connection, the inverter sends reactive power to the grid.

CauseA grid voltage swell pushed the inverter into high-voltage ride-through: it stays connected and sends reactive power to the grid to support it instead of tripping offline.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 44

W08

Low voltage ride through alarm.

Fault

Entering low voltage ride-through at grid connection, the inverter absorbs reactive power from the grid.

CauseA grid voltage dip pushed the inverter into low-voltage ride-through: it stays connected and absorbs reactive power from the grid instead of tripping offline.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 44

W09

Under-frequency derating alarm.

Fault

The frequency is too low, the inverter reduce the power.

CauseGrid frequency has fallen below the derating threshold, so the inverter automatically reduces its output power while the condition lasts.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 44

W10

Over-frequency derating alarm.

Fault

The frequency is too high, the inverter reduce the power.

CauseGrid frequency has risen above the derating threshold, so the inverter automatically reduces its output power while the condition lasts.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 44

W11

Under frequency and rated alarm.

Fault

The frequency is too low, the inverter increases the power.

CauseGrid frequency has fallen below the response threshold and the inverter raises its output power to help support the grid while the condition lasts.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 45

W12

Load Overload Alarm.

Fault

The load is overloaded, and the load should be reduced.

CauseThe connected load has climbed above the inverter's rated output — the warning stage before the overload fault tiers cut the output; the load should be reduced.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 45

W13

DC lightning protection alarm.

Fault

If the DC lightning protector is abnormal, check whether the lightning protector is abnormal.

CauseThe DC-side surge (lightning) protector is reporting an abnormal state — these modules commonly degrade after absorbing a surge and need to be checked.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 45

W14

AC lightning protection alarm.

Fault

If the AC lightning protector is abnormal, check whether the lightning protector is abnormal.

CauseThe AC-side surge (lightning) protector is reporting an abnormal state — these modules commonly degrade after absorbing a surge and need to be checked.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 45

W15

Radiator overtemperature derating alarm.

Fault

The radiator temperature is too high, and the inverter reduces the power.

CauseInverter internal temperature has exceeded the safe operating threshold. Causes include high ambient temperature, blocked cooling vents, failed cooling fan, or installation in direct sunlight.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 45

W16

Ambient overtemperature derating alarm.

Fault

The ambient temperature is too high, and the inverter reduces the power.

CauseInverter internal temperature has exceeded the safe operating threshold. Causes include high ambient temperature, blocked cooling vents, failed cooling fan, or installation in direct sunlight.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 45

W18

Fan 1 alarm.

Fault

Fan 1 stops abnormally, check fan wiring.

CauseInternal cooling fan failure detected. Often caused by dust buildup, bearing wear, or debris fouling the fan blades.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 45

W19

Fan 2 alarm.

Fault

Fan 2 stops abnormally, check fan wiring.

CauseInternal cooling fan failure detected. Often caused by dust buildup, bearing wear, or debris fouling the fan blades.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 45

W20

Fan 3 alarm.

Fault

Fan 3 stops abnormally, check fan wiring.

CauseInternal cooling fan failure detected. Often caused by dust buildup, bearing wear, or debris fouling the fan blades.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 45

W21

Fan 4 alarm.

Fault

Fan 4 stops abnormally, check fan wiring.

CauseInternal cooling fan failure detected. Often caused by dust buildup, bearing wear, or debris fouling the fan blades.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 45

W22

Internal fan alarm.

Fault

Internal fan stops working abnormally, check internal fan wiring.

CauseInternal cooling fan failure detected. Often caused by dust buildup, bearing wear, or debris fouling the fan blades.

Source:T-REX-50KHP3G01-user-manual-.pdf· page 45

Still seeing a code on your T-REX-50KHP3G01?

Send us the code on your screen and a Felicity technician will reply with the exact steps for your unit. Support is free for life — a first diagnosis never needs a callout.

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Related devices

Common questions about T-REX-50KHP3G01 error codes

What is the difference between a fault and a warning on the T-REX-50KHP3G01?: A fault cuts the unit's output and the red LED stays solid — this page lists 105 of them for the T-REX-50KHP3G01. The T-REX-50KHP3G01 manual defines no separate warning table — every listed code stops operation. Resolve the cause of a fault before restarting; warnings can usually be cleared while the unit runs.
Does this page apply to other Felicity models?: No — this table was transcribed specifically from the T-REX-50KHP3G01 manual. Other Felicity devices have their own pages; start from the error-code hub to find the one matching the model number on your unit's label.
Where do these codes come from?: Every entry was transcribed from T-REX-50KHP3G01-user-manual-.pdf — Felicity's official documentation. Each row cites its source manual (and page where printed), so you can verify the wording before acting on it.

Compiled from official Felicity user manuals. Always consult your device manual and a qualified technician before performing repairs.

How to read the severity labels

Fault codes (105)output stops · red LED solid

PV1 overvoltage fault.

PV2 overvoltage fault.

PV3 overvoltage fault.

PV4 overvoltage fault.

PV1 overcurrent fault.

PV2 overcurrent fault.

PV3 overcurrent fault.

PV4 overcurrent fault.

PV1 reverse connection fault.

PV2 reverse connection fault.

PV3 reverse connection fault.

PV4 reverse connection fault.

Battery 1 software overvoltage fault.

Battery 2 software overvoltage fault.

Battery 1 Overvoltage fault.

Battery 2 Overvoltage fault.

Battery 1 Undervoltage fault.

Battery 2 Undervoltage fault.

Battery 1 software overcurrent fault.

Battery 2 software overcurrent fault.

Battery 1 overcurrent fault.

Battery 2 overcurrent fault.

Battery 1 reverse connection fault.

Battery 2 reverse connection fault.

Battery 1 relay open circuit fault.

Battery 2 relay open circuit fault.

Battery 1 relay short circuit fault.

Battery 2 relay short circuit fault.

Battery 1 soft start fault.

Battery 2 soft start fault.

Battery 1 SOC Low fault.

Battery 2 SOC Low fault.

Bus software overvoltage fault.

Bus overvoltage fault.

Bus undervoltage fault.

Positive and negative bus imbalance fault.

Bus soft start fault.

Bus short circuit fault.

Balanced Bridge Software Overcurrent Fault.

Balanced Bridge Overcurrent Fault.

Inverter soft start fault.

Inverter voltage fault.

Inverter software overcurrent fault.

Inverter overcurrent fault.

Inverter short circuit fault.

Inverter voltage DC component fault.

Inverter current DC component fault.

Grid Overvoltage Fault.

Grid Undervoltage Fault.

Grid Over-frequency Fault.

Grid Underfrequency Fault.

Grid Reverse Sequence Fault.

Grid Overload Fault.

Active Islanding Fault.

Grid Imbalance Fault.

Load overload 110% Fault.

Load overload 125% Fault.

Load overload 150% Fault.

Load overload 200% Fault.

EPO Fault.

IGBT over-temperature fault.

Ambient Overtemperature.

Fan 1 Fault.

Fan 2 Fault.

Fan 3 Fault.

Fan 4 Fault.

Internal fan fault.

EEPROM Fault.

12V auxiliary power supply fault.

CT or Hall open circuit fault.

Main and auxiliary DSP communication fault.

MCU Communication Fault.

Leakage current fault.

PV Insulation Impedance fault.

BAT1 Insulation Impedance fault.

BAT2 Insulation Impedance.

Inverter relay open circuit fault.

Short circuit fault of inverter relay.