The short answer
Note when it happens, read the exact code in Solar.web; the installer measures string insulation and repairs.
Plain explanation
From the Fronius manual for the Primo/Symo SnapINverter: Note whether it appears after rain or in the morning (common trigger). Check Solar.web for the exact state code and time. 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.
Steps from the source
- Note whether it appears after rain or in the morning (common trigger)
- Check Solar.web for the exact state code and time
- Do not touch DC cables yourself
- Installer measures insulation of the PV strings and repairs the fault
Source
Fronius support page: SnapINverter (Primo/Symo/Eco) state codes & Datamanager, State codes 475 / 502www.fronius.com ↗
Where installers ask this
- Error 475 (insulation / moisture) on Fronius inverter (r/solar)
- reddit.com/r/SolarUK/comments/1qxd1vk/
- reddit.com/r/SolarDIY/comments/1mty17f/
- reddit.com/r/solar/comments/1lxgtc1/
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.