Fronius State 112 — Grid Frequency Too Low

What Does This Error Mean?

State 112 on a Fronius inverter means grid frequency is below the country's allowed minimum (typically 49.5 Hz in EU, 59.3 Hz in NA). The inverter disconnects per grid code. Most events are transient — chronic State 112 indicates serious grid issues or a generator-fed site.

Affected Models

Fronius Primo
Fronius Symo
Fronius Galvo
Fronius IG Plus
Fronius Tauro

Common Causes

Brief grid frequency drop during major fault or generator outage
Heavy load somewhere on the grid pulling frequency down
Generator-fed site with poor frequency regulation under load
Weak grid with high inertia issues
Inverter calibration drift (rare)

How to Fix It

Confirm the recurrence pattern.

Check Solar.web history. Single events are transient grid issues that recover automatically. Frequent State 112 indicates chronic grid problems.
Document timestamps.

Note exact times State 112 occurs. Patterns at evening peak suggest under-frequency from heavy loads. Random patterns suggest instability.
Check generator sites.

Generator-fed installations often have State 112 when the generator is overloaded or transitioning. Discuss with the generator installer — it may need governor tuning or larger sizing.
Contact utility with documentation.

Recurring State 112 with utility-supplied power is a real grid issue. Provide documented times — the utility can investigate upstream stability.
Verify inverter measurement.

Rarely, an inverter's own frequency measurement drifts and reports false events. An installer with calibrated equipment can verify grid frequency vs the inverter's reading. Calibration drift is rare but possible.

Frequently Asked Questions

What is the difference between Fronius State 109 and 112?

State 109 is grid frequency too high (above 50.5 Hz on 50 Hz grid). State 112 is grid frequency too low (below 49.5 Hz). Both indicate frequency outside grid code limits. Causes and fixes differ — State 109 is rare with utility supply; State 112 more common during grid stress.

Can I run my Fronius on a generator?

Some Fronius inverters work with generators if frequency regulation is good. Smaller generators (1–3 kW class) usually have inadequate regulation. Larger generators with electronic governors can work. Discuss with your installer before relying on generator-PV combination.