What does error 37 mean on a Felicity inverter?

It depends on the model — 2 devices use code 37. On the IVGM5KL-P1G1 it means: LLC soft start failure. The card for each model on this page gives its exact meaning and fix.

How do I clear or fix error 37?

1. Restart the system 2~3 times; 2. The exact steps for each affected model are listed on this page.

Felicity inverter error 37 (F37)

LLC soft start failure

Also displayed as F37 on some models.

Fault — the inverter cuts its output and the red LED stays solid until the fault is cleared.

The exact meaning depends on your model:

IVGM5KL-P1G1

InverterFault

Also applies to:IVGM6KL-P1G1IVGM7K6L-P1G1IVGM8KL-P1G1

What it means

LLC soft start failure — LLC converter soft start failure.

Cause: The LLC converter stage failed to ramp up to its working point during soft start — an internal converter fault rather than a wiring issue.

How to fix it

Restart the system 2~3 times
If the fault still exists, please contact us for help.

Source: Felicitysolar IVGM Series Hybrid inverter Instruction Manual.pdf, p.53

T-REX-50KHP3G01

InverterFault

What it means

Bus undervoltage fault — Bus voltage is too low, shutdown and restart.

Cause: The 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.

How to fix it

Power 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, p.47

Frequently asked questions

What does error 37 mean on a Felicity inverter?: It depends on the model — 2 devices use code 37. On the IVGM5KL-P1G1 it means: LLC soft start failure. The card for each model on this page gives its exact meaning and fix.
Is error 37 a fault or a warning?: 37 is a fault code: the inverter cuts its output and the red LED stays solid until it is cleared.
How do I clear or fix error 37?: 1. Restart the system 2~3 times; 2. The exact steps for each affected model are listed on this page.

Related error codes

Other codes on the IVGM5KL-P1G1

All IVGM5KL-P1G1 codes

Other codes on the T-REX-50KHP3G01

All T-REX-50KHP3G01 codes

Prefer the full written guide? Read the complete Felicity inverter error-code guide

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