3401 on a SMA Solar Technology AG Sunny Boy Smart Energy: Overvoltage at the DC input. This can destroy the inverter
Short answer
On a SMA Solar Technology AG inverter, 3401 means: Overvoltage at the DC input. This can destroy the inverter. The inverter stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 24 September 2026 · 1 source
What it means
The manual says: Overvoltage at the DC input. This can destroy the inverter.
Part involved: DC overvoltage.
When it shows: Overvoltage at the DC input. This can destroy the inverter.
Likely causes:
- SMA corrective measures: Immediately disconnect the inverter from all voltage sources. Check whether the DC voltage is below the maximum input voltage of the inverter. If the DC voltage is below the maximum input voltage of the inverter, reconnect the DC cables to the inverter. If the DC voltage is above the maximum DC voltage of the inverter, ensure that the correct battery has been selected. If the DC voltage exceeds the maximum input voltage of the inverter, ensure that the PV array has been correctly rated or contac.
Is it safe?
Switch the inverter off at its isolator and call an engineer.
| Does the inverter stop? | Yes |
|---|---|
| Severity | Safety lockout |
| Engineer needed? | Yes |
The inverter stops until the fault clears or is reset.
Resetting itself: no.
Manual reset: Reconnect only after DC voltage verified below the maximum input voltage.
What you can check
- Read the event number and message in the SMA Energy app / Sunny Portal (ennexOS) or the inverter's web interface and note the date/time for your installer. A red LED on the inverter means an event has occurred.
- SMA states this overvoltage can destroy the inverter and the inverter must be disconnected immediately by a qualified person - call your installer urgently and do not touch the DC isolator or cables.
What the engineer will check
- Immediately disconnect inverter from all voltage sources; measure DC string voltage against max input voltage; redesign string if above limit; contact SMA Service if inverter damaged.
Who to ask for: MCS PV installer.
Certification: Qualified electrician (BS 7671; MCS-certified PV installer for work on the PV array/DC side).
What you might notice
Sources
- Operating manual SUNNY BOY SMART ENERGY 3.6/4.0/5.0/6.0/8.0/9.9 ↗ · SBSExx-50-BE-en-12 Version 1.2 · page 86 · Reviewed 24 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 24 September 2026