Fronius State 105 — Grid Voltage Too High

What Does This Error Mean?

State 105 on a Fronius inverter means grid voltage exceeds the maximum allowed by the country's grid code (typically 253V for a 230V grid). The inverter disconnects to protect itself and the grid. Cause is usually local PV oversupply or a transformer tap setting too high. Document and contact the utility.

Affected Models

Fronius Primo
Fronius Symo
Fronius Galvo
Fronius IG Plus
Fronius Tauro

Common Causes

High grid voltage in PV-rich neighbourhoods
Local distribution transformer set to a high tap
Long thin distribution line with voltage rise from PV production
Weak grid with limited voltage regulation
Inverter voltage measurement calibration drift (rare)

How to Fix It

Check whether State 105 is recurring.

Open the Fronius Solar.web monitoring portal and review the last week. State 105 events at predictable times (e.g., midday) indicate chronic grid voltage too high. One-off events from grid faults clear themselves.
Test household voltage at peak production.

Use a multimeter on a kitchen outlet at midday on a sunny day. Voltage above 253V (230V grid) confirms a real grid issue. Document with date, time, and reading.
Contact your utility.

Provide documented voltage readings. Utilities often adjust transformer taps or add voltage regulation in PV-saturated areas. The service is typically free — they have an obligation to maintain voltage within tolerance.
Ask installer about Volt-VAR support.

Modern Fronius inverters support Volt-VAR control — they can lower power factor when voltage is high to help local voltage. Some grid codes require this enabled by default; others allow it as an option. An installer can configure it.
Discuss wider voltage settings.

Some jurisdictions allow installers to widen voltage limits within regulatory tolerance. This is a workaround, not a fix. The grid issue should still be addressed by the utility.

Frequently Asked Questions

Why does my Fronius keep getting State 105 in summer?

Summer has the highest production. PV-fed grids tend to have elevated voltage during peak production — long lines with many PV systems push voltage above limits. State 105 in summer afternoons is the classic symptom. Contact the utility for tap adjustment or grid reinforcement.

Will State 105 reduce my Fronius's annual production?

Yes — every State 105 event is lost production. Annual losses range from 1% (occasional events) to 15% (chronic events lasting hours daily). A Solar.web report shows the precise impact for your system.