302 on a SMA Solar Technology AG Sunny Boy: The inverter has reduced its power due to a too-high grid voltage to ensure grid stability

What it means

The manual says: The inverter has reduced its power due to a too-high grid voltage to ensure grid stability.

Part involved: power derating.

When it shows: The inverter has reduced its power due to a too-high grid voltage to ensure grid stability.

Likely causes:

• SMA corrective measures: If possible, check the grid voltage and observe how often fluctuations occur. If fluctuations occur frequently and this message is displayed often, contact the grid operator and request approval to change the operating parameters of the inverter. If the grid operator gives approval, discuss any changes to the operating parameters with the Service.

Is it safe?

The inverter keeps running with some functions stopped.

Resetting itself: yes.

Manual reset: Automatic when condition clears.

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.
• Occasional derating on sunny days is expected where local grid voltage/frequency is high; if frequent, tell your installer.

What the engineer will check

• Log grid voltage/frequency; if frequent, request DNO approval before any parameter change, and agree changes with SMA Service.

Who to ask for: PV installer.

Certification: Installer liaison with the DNO; any change to grid-protection settings needs DNO agreement (G98/G99) and the manufacturer's installer/grid code.

What you might notice

• Solar generation lower than usual

Sources

• Operating manual SUNNY BOY 3.0/3.6/4.0/5.0/6.0 ↗ · SBxx-1AV-41-BE-en-21 Version 2.1 · page 86 · Reviewed 24 September 2026

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

Reviewed: 24 September 2026