The short answer
It auto-resets: check other charging equipment and that the battery voltage setting isn't lower than the battery.
Plain explanation
From the Victron manual for the SmartSolar MPPT: Auto-resets. Check other charging equipment. The rest of the checklist is below; work through it in order. Owners can do the app and visual checks; any work on the wiring is for the installer.
Steps from the source
- Auto-resets
- Check other charging equipment
- Check battery voltage setting (12/24/48) is not lower than battery
Source
Victron MPPT / charger error codes (official docs), Err 2www.victronenergy.com ↗
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.