Solar · Error codes
Why does my Fox ESS inverter show Grid Volt Fault or 10min Volt Fault on sunny days?
Short answer
Both mean mains voltage went outside the limits the inverter must obey under UK grid rules; 10min Volt Fault uses a ten-minute average. Fox says the inverter reconnects automatically. If it happens on most sunny afternoons, your local voltage may be high: ask your installer to log it and involve the network operator (checked 24 September 2026).
Last checked 24 September 2026 · 1 source
In more detail
- The inverter must disconnect to comply with G98/G99 protection settings.
- Installer checks: AC cable voltage rise, terminations, correct UK grid code.
- DNO can investigate supply voltage above statutory limits (230 V +10%/-6%).
The facts, dated
- 01Fox H1 G2 manual describes 10min Volt Fault as grid voltage out of range for the last 10 minutes.
manufacturer · UK · checked 24 September 2026 · fox-ess.com
Sources
Last checked: 24 September 2026