The short answer
Check grid voltage and contact the power company; OV threshold or HVRT may change only with their consent.
Plain explanation
From the GoodWe manual for the ET / ET Plus+ / BT: Occasional trips recover automatically. If frequent, check grid voltage is in range. 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
- Occasional trips recover automatically
- If frequent, check grid voltage is in range
- Contact the power company
- OV threshold / HVRT may be changed only with power-company consent (installer)
- Check AC breaker and output cables
Source
GoodWe ET / ET Plus+ / BT User Manual EN, Ch.9 Troubleshooting, Ch.9 Troubleshooting, pdf p64-71en.goodwe.com ↗
Where installers ask this
- ACVoltHigh error message (r/solar)
- reddit.com/r/nzsolar/comments/1og5wtj/
- reddit.com/r/solar/comments/1t65om6/
- reddit.com/r/AskElectricians/comments/1k1ivna/
- reddit.com/r/solar/comments/wkehxw/
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.