HESP series hybrid inverters (single-phase 4-12 kW and three-phase 8-12 kW)
SRNE 21 error code
Fan failure (FanFail): the hardware detected that a cooling fan is blocked or not turning.
Likely causes
- Foreign matter or insect nest blocking the fan
- Fan connector loose or disconnected
- Worn fan bearing or failed fan motor
- Fan cable damaged by rodents
Checks to run, in order
- 1Power off, then turn the fan by hand to feel for obstruction or stiffness, as the manual instructs
- 2Check the fan connector on the control board
- 3Inspect the blades and cable for damage
- 4Confirm whether the fault appears at power-up or only under load
Fixes
- Remove the obstruction and reseat the connector
- Replace a stiff or failed fan
- Restart and confirm the fan runs through a load cycle
When to escalate
If the fan is free, connected and still not driven, the fan drive circuit needs distributor repair.
Fix it with the right tools
Check the system around the fault before replacing parts: load, battery bank, PV string and commissioning settings. If you need a second opinion, send the code and your inverter model to our team.
Before you open the inverter
- Isolate both the AC and DC sides, then confirm the display is dead before touching terminals.
- Use insulated tools and one hand where possible. DC arcs do not self-extinguish like AC.
- If you see burnt terminals, swollen cells, leaking electrolyte or a burning smell, stop and escalate instead of resetting the fault.
Questions installers ask
What does SRNE 21 mean?
Fan failure (FanFail): the hardware detected that a cooling fan is blocked or not turning.
How do I fix SRNE 21?
Remove the obstruction and reseat the connector Replace a stiff or failed fan Restart and confirm the fan runs through a load cycle
When should I escalate SRNE 21?
If the fan is free, connected and still not driven, the fan drive circuit needs distributor repair.
Can I reset SRNE 21 myself?
Only after isolating the AC and DC sides and running the checks above. If SRNE 21 returns immediately, stop resetting it and escalate; a repeating fault usually points to a real circuit, battery or hardware problem.
Which models show SRNE 21?
SRNE 21 is documented for HESP series hybrid inverters (single-phase 4-12 kW and three-phase 8-12 kW). Confirm the code on your own unit's display or manual before ordering parts.
More SRNE error codes
- SRNE 01Battery undervoltage alarm: the battery voltage has fallen below the [Batt. Under volt. alarm] value under Battery Setup, and the alarm does not by itself stop the output.
- SRNE 02Battery discharge average current overcurrent, detected by software (BatOverCurrSw); the inverter limits or stops discharge.
- SRNE 03Battery not connected (BatOpen): the inverter cannot see a battery on the DC side and stops the output.
- SRNE 04Battery undervoltage stop-discharge (BatLowEod): the battery has reached the low-voltage cut-off and the inverter has stopped discharging.
- SRNE 05Battery overcurrent detected by hardware protection (BatOverCurrHw); the inverter shuts the output down.
- SRNE 06Charging overvoltage protection (BatOverVolt): battery voltage rose above the over-voltage cut-off and charging was stopped.
Guidance reviewed 17 October 2026 by the Mishka Energy installer team. Error codes vary by brand, model family and firmware; confirm against the manufacturer manual.
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