The short answer
ON = both OK, BLINK 1 = BMS comms failed, BLINK 2 = meter comms failed, OFF = both failed.
Plain explanation
From the GoodWe manual for the ET / ET Plus+ / BT: Read the COM LED: ON = BMS and meter OK. BLINK 1 = BMS comm failed – installer checks battery comm cable. 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
- Read the COM LED: ON = BMS and meter OK
- BLINK 1 = BMS comm failed – installer checks battery comm cable
- BLINK 2 = meter comm failed – installer checks meter cable
- OFF = both failed
Source
GoodWe ET / ET Plus+ / BT User Manual EN, Ch.9 Troubleshooting, Ch.9 LED tableen.goodwe.com ↗
Where installers ask this
- Battery not discharging on GoodWe inverter (r/SolarPakistan)
- reddit.com/r/SolarPakistan/comments/1tvg6f1/
- reddit.com/r/SolarPakistan/comments/1wgqf74/
- reddit.com/r/SolarDIY/comments/1rovstx/
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.