501 on a SMA Solar Technology AG Sunny Boy: The grid frequency is not within the permissible range. The inverter has disconnected from the utility grid
Short answer
On a SMA Solar Technology AG inverter, 501 means: The grid frequency is not within the permissible range. The inverter has disconnected from the utility grid. 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: The grid frequency is not within the permissible range. The inverter has disconnected from the utility grid.
Part involved: grid frequency / anti-islanding / DC injection monitoring.
When it shows: The grid frequency is not within the permissible range. The inverter has disconnected from the utility grid.
Likely causes:
- SMA corrective measures: If possible, check the grid frequency 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?
| Does the inverter stop? | Yes |
|---|---|
| Severity | Fault — clears by itself when the condition goes |
| Engineer needed? | Yes |
The inverter stops until the fault clears or is reset.
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.
- Check whether there is a power cut or grid work in your area.
- If it happens once and the inverter resumes feeding in on its own, no action is needed; if the event keeps recurring, contact your installer.
What the engineer will check
- Check grid frequency stability and AC wiring to the feed-in meter; for 601 check for DC on the grid connection; any change of monitoring thresholds only with DNO approval and SMA Service.
Who to ask for: PV installer / electrician; DNO liaison.
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
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 87 · Reviewed 24 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 24 September 2026