GoodWe ET battery charged all day but won't discharge at night. Why?

The short answer

Check household load is above about 150 W, SOC vs DOD, the charge time window and meter/CT direction.

Plain explanation

From the GoodWe manual for the ET / ET Plus+ / BT: Household load must be above about 150 W. Check SOC is above 1 – DOD (battery recharges to 20% + (1-DOD)/2 first). 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

Household load must be above about 150 W
Check SOC is above 1 – DOD (battery recharges to 20% + (1-DOD)/2 first)
Check the charge time window in SolarGo/SEMS isn't blocking discharge
Installer checks smart meter / CT connection and direction

Source

GoodWe ET / ET Plus+ / BT User Manual EN, Ch.9 Troubleshooting, Ch.9 Troubleshooting, pdf p71en.goodwe.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.