4017 on a SMA Solar Technology AG Sunny Boy Smart Energy: The displayed input is in reverse polarity or reverse current has been detected in the input

What it means

The manual says: The displayed input is in reverse polarity or reverse current has been detected in the input.

Part involved: DC input polarity / string.

When it shows: The displayed input is in reverse polarity or reverse current has been detected in the input.

Likely causes:

• SMA corrective measures: Check the correct polarity of the connected PV modules. Ensure correct design and circuitry of the PV array. If solar irradiation is sufficient, check whether the same voltage is present at the DC inputs. Ensure that no PV module is defective.

Is it safe?

The inverter keeps running with some functions stopped.

Resetting itself: unknown.

Manual reset: See engineer checks.

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.
• Contact your installer - this concerns the DC string wiring.

What the engineer will check

• Check string connection/polarity on the named input, reverse currents, string design and module defects; reset string-failure detection if an input is no longer used; contact SMA Service.

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

• Error code shown on inverter or app
• Solar generation lower than usual
• Solar panels not generating at all

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 91 · Reviewed 24 September 2026

A code explains what the controller detected, not a confirmed root cause.

Reviewed: 24 September 2026