HESP series hybrid inverters (single-phase 4-12 kW and three-phase 8-12 kW)
SRNE 29 error code
Low bus voltage / internal battery boost circuit failure (BusVoltLow).
Likely causes
- Internal battery boost circuit failure
- Battery voltage collapsing under load
- Failed bus sensing
- DC board hardware fault
Checks to run, in order
- 1Measure battery voltage at rest and under load
- 2Check battery cables and breaker for voltage drop
- 3Restart once and observe whether the fault returns under load
- 4Compare the inverter battery reading with a meter
Fixes
- Correct battery wiring or a weak bank first
- If the battery is healthy, refer the unit for boost-circuit repair
When to escalate
This code indicates an internal boost-circuit failure, so a healthy battery and correct wiring mean the inverter must go to SRNE service.
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 29 mean?
Low bus voltage / internal battery boost circuit failure (BusVoltLow).
How do I fix SRNE 29?
Correct battery wiring or a weak bank first If the battery is healthy, refer the unit for boost-circuit repair
When should I escalate SRNE 29?
This code indicates an internal boost-circuit failure, so a healthy battery and correct wiring mean the inverter must go to SRNE service.
Can I reset SRNE 29 myself?
Only after isolating the AC and DC sides and running the checks above. If SRNE 29 returns immediately, stop resetting it and escalate; a repeating fault usually points to a real circuit, battery or hardware problem.
Which models show SRNE 29?
SRNE 29 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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