W09Warning

Felicity inverter error W09

Overload

Warning — the red LED flashes and the inverter keeps running. Deal with it before it escalates.

Severity differs by model — check your model below.

The exact meaning depends on your model:

T-REX-10KHP3G01

InverterWarning

What it means

Overload — Overload warning. Audible alarm: beep twice every second.

Cause: The connected load exceeds the inverter's continuous output rating; the warning sounds before overload protection cuts the output.

How to fix it

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

Source: T-REX-10KHP3G01-Inverter-User-Guide.pdf, p.27

T-REX-10KLP3G01

InverterWarning

What it means

Overload — Overload warning. Audible alarm: beep twice every second.

Cause: The connected load exceeds the inverter's continuous output rating; the buzzer beeps twice every second and protection will cut the output if the overload is not reduced.

How to fix it

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

Source: T-REX-10KLP3G01-Inverter-User-Guide.pdf, p.27

T-REX-50KHP3G01

InverterFault

What it means

Under-frequency derating alarm — The frequency is too low, the inverter reduce the power.

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

How to fix it

  1. Power down the inverter, wait 5 minutes for capacitors to discharge, then restart.
  2. 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.44

Apollo-5KLP1G01-MX

Energy storage systemWarning

Also applies to:Apollo-5KLP1G01-M1Apollo-5KLP1G01-M2Apollo-4K6LP1G01-MXApollo-4K6LP1G01-M1Apollo-4K6LP1G01-M2

What it means

Overload — Overload warning. Audible alarm: beep twice every second.

Cause: The connected load is drawing more power than the inverter's rated output capacity; the unit is warning before overload protection cuts the output.

How to fix it

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

Source: Apollo-5KLP1G01-All-in-one-ESS-User-Guide.pdf, p.42

Frequently asked questions

What does error W09 mean on a Felicity inverter?
It depends on the model — 4 devices use code W09. On the T-REX-10KHP3G01 it means: Overload. The card for each model on this page gives its exact meaning and fix.
Is error W09 a fault or a warning?
It depends on the model: on some models W09 is a fault (output cut, red LED solid), on others a warning (red LED flashing, unit keeps running). Check the card for your model on this page.
How do I clear or fix error W09?
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. The exact steps for each affected model are listed on this page.

Related error codes

Other codes on the T-REX-10KHP3G01

All T-REX-10KHP3G01 codes

Other codes on the T-REX-10KLP3G01

All T-REX-10KLP3G01 codes

Other codes on the T-REX-50KHP3G01

All T-REX-50KHP3G01 codes

Other codes on the Apollo-5KLP1G01-MX

All Apollo-5KLP1G01-MX 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.