Fronius Inverter State 240 — Not Feeding In

What Does This Error Mean?

Fronius State 240 means the inverter cannot synchronise with the grid or the AC connection is not available. Check that the AC isolator switch between the inverter and the switchboard is turned on, and that there is no local power outage.

Affected Models

Fronius Primo
Fronius Symo
Fronius Galvo
Fronius SnapINverter Series
Fronius GEN24 Plus

Common Causes

AC isolator switch turned off
Power outage in the area — Fronius inverters require grid power to operate (anti-islanding safety requirement)
Loose or corroded AC connection at the inverter
Grid fault or frequency instability preventing synchronisation
Residual current device (RCD) tripped on the solar circuit

How to Fix It

Check the AC isolator switch.

Locate the AC isolator switch on the wall near the inverter (usually labelled Solar AC Isolator or Grid Isolator). Confirm it is fully in the ON position. This is the most common cause of State 240.
Check the switchboard for tripped breakers or RCDs.

Go to your main switchboard and check whether any circuit breaker or RCD has tripped — especially the solar circuit breaker. Reset any tripped device and check whether the inverter recovers.
Check for a local power outage.

Fronius inverters cannot operate without grid power — it is a mandatory safety requirement to prevent backfeed during outages. If there is a power outage or the grid has just restored, wait 5 minutes for the inverter to complete its reconnect delay.
Power-cycle the inverter.

Turn off the AC isolator, then set the DC switch on the inverter to OFF. Wait 2 minutes, then turn DC back on and then the AC isolator. Allow 5 minutes for the inverter to restart and reconnect.
Check Solar.web for additional event codes.

Log in to Solar.web and view the Events log. Secondary codes alongside State 240 can pinpoint whether this is an AC wiring issue, a grid fault, or a communication problem.

When to Call a Professional

If the AC isolator is on and there is no outage but State 240 persists, a licensed electrician should check the AC wiring connections at the inverter and switchboard.

Frequently Asked Questions

Fronius State 240 appeared overnight and has not cleared — what now?

If the AC isolator is on and power is available but State 240 has not cleared after a power-cycle, the AC wiring at the inverter terminals may have a loose connection. Contact a licensed solar electrician to inspect the wiring.

Fronius State 240 after a power outage — is this normal?

Yes — after a power outage, Fronius inverters wait a mandatory 60–300 seconds (set by your local regulations) before reconnecting to the grid. This is a safety requirement and the inverter will resume production automatically.