56Fault

DEYE inverter error 56 (F56)

DC busbar voltage is too low

Also displayed as F56 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:

SUN G01P3-EU-BM8 Series

InverterFault

Also applies to:SUN-120K-G01P3-EU-BM8SUN-125K-G01P3-EU-BM8SUN-130K-G01P3-EU-BM8SUN-135K-G01P3-EU-BM8SUN-136K-G01P3-EU-BM8SUN-7K-G02P1-EU-AM2SUN-7.5K-G02P1-EU-AM2SUN-8K-G02P1-EU-AM2+3

What it means

DC busbar voltage is too low — The DC bus voltage is below the limit.

Cause: The PV input voltage is low - it always happens in the early morning; if F56 appears while the inverter is running, a loss of the driver or firmware that needs updating may be responsible.

How to fix it

  1. Check the PV voltage and the Ubus voltage - in the early morning this normally just reflects low PV input voltage
  2. If it shows while the inverter is running, the driver may have been lost or the firmware may need updating
  3. Restart the inverter; if the fault still exists, contact your installer or Deye service.

Source: 041_BManual_SUN-120_125_130_135_136K-G01P3-EU-BM8_20251021_en_a2166559.pdf, p.63 · 065_BManual_SUN-7_7.5_8K-G02P1-EU-AM2_20260625_en_4466f08b.pdf, p.53 · 032_BManual_SUN-9_10_10.5K-G02P1-EU-AM2_20260625_en_df0f2106.pdf, p.53

SUN G03/G01P3-AM8 Series

InverterFault

Also applies to:SUN-60K-G03SUN-70K-G03SUN-75K-G03SUN-80K-G03SUN-90K-G03SUN-100K-G03SUN-110K-G03SUN-60K-G01P3-EU-AM8-LV+7

What it means

DC busbar voltage is too low — The DC bus voltage is below the limit.

Cause: The PV input voltage is low - it always happens in the early morning; if F56 appears while the inverter is running, a loss of the driver or firmware that needs updating may be responsible.

How to fix it

  1. Check the PV voltage and the Ubus voltage - in the early morning this normally just reflects low PV input voltage
  2. If it shows while the inverter is running, the driver may have been lost or the firmware may need updating
  3. Restart the inverter; if the fault still exists, contact your installer.

Source: 033_BManual_SUN-70_75_80_90_100_110K-G03_20260702_en_a9db1e1b.pdf, p.63 · 042_BManual_SUN-120_125_130_135_136K-G01P3-EU-AM8_20260702_en_05f936e3.pdf, p.62 · 060_BManual_SUN-60_70_75K-G01P3-EU-AM8-LV_20260701_en_f559aeec.pdf, p.62 · +1 more official manuals

SUN G04/G05/G06 3-Phase

InverterFault

Also applies to:SUN-6K-G06-LV-P1SUN-8K-G06-LV-P1SUN-6K-G06P3-EU-BM2-LV-P1SUN-8K-G06P3-EU-BM2-LV-P1SUN-10K-G05-LVSUN-12K-G05-LVSUN-15K-G05-LVSUN-15K-G06P3-EU-BM2-P1+71

What it means

DC busbar voltage is too low — The DC bus voltage is below its lower limit.

Cause: The PV input voltage is low - it always happens in the early morning; if F56 appears while the inverter is running, it may be loss of a driver or firmware that needs an update.

How to fix it

  1. Check the PV voltage and Ubus voltage; update the firmware if needed.
  2. Restart the inverter; if the fault still exists, contact your installer or Deye service.

Source: 063_BManual_SUN-6K-G06-LV-P1_20250923_en_30a96699.pdf, p.59 · 031_BManual_SUN-1_1.5_2_2.2_2.5_2.7_3_3.3_3.6_4K-G04P1-EU-AM1_20260624_en_15adc00c.pdf, p.55 · 036_BManual_SUN-3_4_5_6_7_8_9_10_12_15K-G06P3-EU-BM2_20250506_en_0eb78440.pdf, p.59

SUN LP1 Hybrid Series

InverterFault

Also applies to:SUN-3.6K-SG05LP1-EU-SM2-PSUN-5K-SG05LP1-EU-SM2-PSUN-6K-SG05LP1-EU-SM2-PSUN-7K-SG05LP1-EU-SM2-PSUN-7.6K-SG05LP1-EU-SM2-PSUN-8K-SG05LP1-EU-SM2-PSUN-10K-SG05LP1-EU-SM2-PSUN-7.6K-SG01LP1-EU+21

What it means

DC busbar voltage is too low — Battery voltage low: the DC busbar voltage is too low.

Cause: The battery voltage is too low.

How to fix it

  1. Check whether the battery voltage is too low; if it is, use PV or grid power to charge the battery.
  2. Seek help from Deye if the inverter cannot go back to the normal state.

Source: 039_BManual_SUN-3.6_5_6_7_7.6_8_10K-SG05LP1-EU-SM2-P_20260428_en_70c401a6.pdf, p.50 · 043_BManual_SUN-12_14_16K-SG01LP1-EU_20260519_en_703e15ac.pdf, p.46 · 052_BManual_SUN-_3.6-6_K-OG01LP1-EU-AM2_20260406_en_dc31b173.pdf, p.46 · +4 more official manuals

SUN SG01HP3/SG02HP3 Hybrid

InverterFault

Also applies to:SUN-5K-SG01HP3-EU-AM2SUN-6K-SG01HP3-EU-AM2SUN-8K-SG01HP3-EU-AM2SUN-10K-SG01HP3-EU-AM2SUN-12K-SG01HP3-EU-AM2SUN-15K-SG01HP3-EU-AM2SUN-20K-SG01HP3-EU-AM2SUN-25K-SG01HP3-EU-AM2+9

What it means

Battery 1 Voltage Low — BAT1_VoltLow_Fault - the terminal voltage of battery input 1 is too low.

Cause: The voltage measured at the battery 1 terminals is below the limit.

How to fix it

  1. Check whether the battery 1 terminal voltage is low
  2. Restart the inverter 2 times and restore the factory settings.

Source: 037_BManual_SUN-5_6_8_10_12_15_20_25K-SG01HP3-EU-AM2_20260224_en_9ef2717c.pdf, p.52 · 050_BManual_SUN-29.9_30_35_40_50K-SG01HP3-EU-BM3_4_20260224_en_544e1b2f.pdf, p.53 · 062_BManual__SUN-60_70_75_80K-SG02HP3-EU-EM6_20260224_en_38cbc9f6.pdf, p.53

SUN SG02LP2-US Hybrid

InverterFault

Also applies to:SUN-5K-SG02LP2-US-AM2SUN-6K-SG02LP2-US-AM2SUN-7.6K-SG02LP2-US-AM2SUN-8K-SG02LP2-US-AM2SUN-10K-SG02LP2-US-AM3SUN-12K-SG02LP2-US-AM3SUN-5K-SG04LP3-EUSUN-6K-SG04LP3-EU+15

What it means

DC Busbar Voltage Too Low — DC busbar voltage is too low - battery voltage low.

Cause: The DC busbar voltage is too low because the battery voltage is too low.

How to fix it

  1. Check whether the battery voltage is too low
  2. If the battery voltage is too low, use PV or grid to charge the battery
  3. Seek help from us if it cannot go back to the normal state.

Source: 059_BManual_SUN-5_6_7.6_8_10_12K-SG02LP2-US-AM2_AM3_20260406_en_fb6a30c7.pdf, p.55 · 038_BManual_SUN-5_6_8_10_12K-SG04LP3-EU_20260319_en_081932c1.pdf, p.48 · 040_BManual_SUN-3_4_5_6_8_10_12K-SG05LP3-EU-SM2_20260319_en_b0183b7d.pdf, p.48 · +1 more official manuals

AI-W5.1 ESS

Energy storage systemFault

Also applies to:AI-W5.1-5P3-EU-B-ESSAI-W5.1-6P3-EU-B-ESSAI-W5.1-8P3-EU-B-ESSAI-W5.1-10P3-EU-B-ESSAI-W5.1-12P3-EU-B-ESS

What it means

DC busbar voltage is too low — BUS voltage is too low (battery voltage low).

Cause: The internal BUS voltage is below its limit - typically the battery voltage is too low.

How to fix it

  1. Check whether the battery voltage is too low; if so, use PV or grid to charge the battery.
  2. Seek help from Deye if it does not recover.

Source: 002_Download_4e90fe7a.pdf, p.48

GB-SL / GB-SL Pro ESS

Energy storage systemFault

Also applies to:GB-SL5K-EUGB-SL6K-EUGB-SL8K-EUGB-SL10K-EUGB-SL12K-EUGB-SL15K-EUGB-SL20K-EUGB-SL Pro 5K-EU+6

What it means

BAT1_VoltLow_Fault — Battery 1 terminal voltage is too low.

Cause: The voltage measured at the battery 1 terminals is below the limit - the battery is over-discharged or the settings are wrong.

How to fix it

  1. Check the battery 1 terminal voltage, restart the inverter twice and restore the factory settings.
  2. Seek help from Deye if it does not recover.

Source: 081_deye_gb_sl_pro_user_manual_46fa941a.pdf, p.51 · 010_Download_cc05df18.pdf, p.46

Frequently asked questions

What does error 56 mean on a DEYE inverter?
It depends on the model — 12 devices use code 56. On the SUN G01P3-EU-BM8 Series it means: DC busbar voltage is too low. The card for each model on this page gives its exact meaning and fix.
Is error 56 a fault or a warning?
56 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 56?
1. Check the PV voltage and the Ubus voltage - in the early morning this normally just reflects low PV input voltage. The exact steps for each affected model are listed on this page.

Related error codes

Other codes on the SUN G01P3-EU-BM8 Series

All SUN G01P3-EU-BM8 Series codes All SUN G02P1-EU Series codes

Other codes on the SUN G03/G01P3-AM8 Series

All SUN G03/G01P3-AM8 Series codes

Other codes on the SUN G04/G05/G06 3-Phase

All SUN G04/G05/G06 3-Phase codes All SUN G04P1/G05P1 Series codes All SUN G06P3-EU Series codes

Other codes on the SUN LP1 Hybrid Series

All SUN LP1 Hybrid Series codes

Other codes on the SUN SG01HP3/SG02HP3 Hybrid

All SUN SG01HP3/SG02HP3 Hybrid codes

Other codes on the SUN SG02LP2-US Hybrid

All SUN SG02LP2-US Hybrid codes All SUN SG04LP3/SG05LP3 Hybrid codes

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

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