21Fault

DEYE inverter error 21 (F021)

DC leakage flow fault

Also displayed as F021 / F21 on some models.

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

The exact meaning depends on your model:

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 leakage flow faultLeakage current in the DC circuit exceeded the protection threshold. The manual notes this code has hardly ever appeared in the field.

Cause: Leakage current in the DC circuit exceeded the protection threshold.

How to fix it

Restart the inverter; if the code persists after the restart, contact your installer or Deye service and provide the inverter serial number, the installation date and the displayed error code.

Source: 041_BManual_SUN-120_125_130_135_136K-G01P3-EU-BM8_20251021_en_a2166559.pdf, p.62 · 065_BManual_SUN-7_7.5_8K-G02P1-EU-AM2_20260625_en_4466f08b.pdf, p.51 · 032_BManual_SUN-9_10_10.5K-G02P1-EU-AM2_20260625_en_df0f2106.pdf, p.51

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 leakage flow faultLeakage current in the DC circuit exceeded the protection threshold.

Cause: Leakage current in the DC circuit exceeded the protection threshold.

How to fix it

Restart the inverter; if the fault is not ruled out, contact the installer or the manufacturer's customer service.

Source: 033_BManual_SUN-70_75_80_90_100_110K-G03_20260702_en_a9db1e1b.pdf, p.62 · 042_BManual_SUN-120_125_130_135_136K-G01P3-EU-AM8_20260702_en_05f936e3.pdf, p.61 · 060_BManual_SUN-60_70_75K-G01P3-EU-AM8-LV_20260701_en_f559aeec.pdf, p.61 · +1 more official manuals

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+27

What it means

DC leakage flow faultLeakage current flow detected on the DC side.

Cause: DC leakage-current monitoring detected current flowing to ground above the limit.

How to fix it

Restart the inverter; if the fault is not ruled out, contact the installer or manufacturer customer service.

Source: 063_BManual_SUN-6K-G06-LV-P1_20250923_en_30a96699.pdf, p.57

Also applies to:SUN-1K-G04P1-EU-AM1SUN-1.5K-G04P1-EU-AM1SUN-2K-G04P1-EU-AM1SUN-2.2K-G04P1-EU-AM1SUN-2.5K-G04P1-EU-AM1SUN-2.7K-G04P1-EU-AM1SUN-3K-G04P1-EU-AM1SUN-3.3K-G04P1-EU-AM1+36

What it means

DC leakage flow faultLeakage current flow detected on the DC side.

Cause: DC leakage-current monitoring detected current flowing to ground above the limit.

How to fix it

Deye states this code has hardly ever appeared in the field; contact your installer or Deye service if it occurs.

Source: 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.53 · 036_BManual_SUN-3_4_5_6_7_8_9_10_12_15K-G06P3-EU-BM2_20250506_en_0eb78440.pdf, p.57

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

BUS OvercurrentTz_HV_Overcurr_Fault - overcurrent on the internal high-voltage BUS.

Cause: The DC BUS current exceeded the limit, typically because the PV input current or the battery current setting is too high.

How to fix it

  1. Check the PV input current and the battery current setting
  2. Restart the system 2~3 times.

Source: 037_BManual_SUN-5_6_8_10_12_15_20_25K-SG01HP3-EU-AM2_20260224_en_9ef2717c.pdf, p.50 · 050_BManual_SUN-29.9_30_35_40_50K-SG01HP3-EU-BM3_4_20260224_en_544e1b2f.pdf, p.51 · 062_BManual__SUN-60_70_75_80K-SG02HP3-EU-EM6_20260224_en_38cbc9f6.pdf, p.51

Also applies to:SUN-5K-SG04LP3-EUSUN-6K-SG04LP3-EUSUN-8K-SG04LP3-EUSUN-10K-SG04LP3-EUSUN-12K-SG04LP3-EUSUN-3K-SG05LP3-EU-SM2SUN-4K-SG05LP3-EU-SM2SUN-5K-SG05LP3-EU-SM2+9

What it means

BUS OvercurrentTz_HV_Overcurr_fault - overcurrent on the internal high-voltage BUS.

Cause: The DC BUS current exceeded the limit, typically because the PV input current or the battery current setting is too high.

How to fix it

  1. Check the PV input current and the battery current setting
  2. Restart the system 2~3 times
  3. If the fault still exists, contact us for help.

Source: 038_BManual_SUN-5_6_8_10_12K-SG04LP3-EU_20260319_en_081932c1.pdf, p.46 · 040_BManual_SUN-3_4_5_6_8_10_12K-SG05LP3-EU-SM2_20260319_en_b0183b7d.pdf, p.46 · 044_BManual_SUN-14_15_16_18_20K-SG05LP3-EU-SM2_20260319_en_ac7cdbd1.pdf, p.46

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-ESSGB-SL5K-EUGB-SL6K-EUGB-SL8K-EU+11

What it means

Tz_HV_Overcurr_faultBUS over-current.

Cause: Current on the internal high-voltage BUS exceeded the limit - PV input current or battery current settings too high.

How to fix it

  1. Check the PV input current and battery current settings, and restart the system 2-3 times.
  2. If the fault still exists, contact Deye for help.

Source: 002_Download_4e90fe7a.pdf, p.47 · 081_deye_gb_sl_pro_user_manual_46fa941a.pdf, p.50 · 010_Download_cc05df18.pdf, p.45

GB-A HV Battery

BatteryFault

Also applies to:GB-A

What it means

ALARM_ID_POS_RELAY_ADHESIONTotal positive relay bonding (main positive relay contacts stuck).

Cause: The main positive relay contacts are welded closed, so the pack cannot be disconnected on the positive path.

How to fix it

Switch the battery off and take it out of service; contact Deye support for relay service.

Source: 008_deye_ess_user_manual_gb_a_jpnen_v02_20250829_3fea617e.pdf, p.13

Frequently asked questions

What does error 21 mean on a DEYE inverter?
It depends on the model — 11 devices use code 21. On the SUN G01P3-EU-BM8 Series it means: DC leakage flow fault. The card for each model on this page gives its exact meaning and fix.
Is error 21 a fault or a warning?
21 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 21?
Restart the inverter; if the code persists after the restart, contact your installer or Deye service and provide the inverter serial number, the installation date and the displayed error code. The exact steps for each affected model are listed on this page.

Related error 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.