Growatt SPH 'AC V Outrange'. Grid or inverter?

The short answer

Check AC voltage is within spec and the grid connection; persistent means Growatt service.

Plain explanation

From the Growatt manual for the SPH 3000-6000TL BL-UP: Check AC voltage is within spec. Installer checks the grid connection. The rest of the checklist is below; work through it in order. Installer only: DC and AC work on a live PV system is dangerous, so owners should note the code and call their installer. Grid limits depend on your country, so check your national code and grid operator rules.

Steps from the source

Check AC voltage is within spec
Installer checks the grid connection
Persists → Growatt service

Source

Growatt SPH 3000-6000TL BL-UP Installation & Operation Manual (Growatt doc, distributor-hosted), §9.2 Fault list, §9.2 AC V Outrangemidsummerwholesale.co.uk ↗

Where installers ask this

General guidance based on the manufacturer's manual or the named source. Always follow the current manual for your exact model and your national code. DC and AC electrical work is for qualified installers only. Not affiliated with or endorsed by any brand named; trademarks belong to their owners.