GoodWe RS485 Controller — Home Assistant add-on repository

Replaces a GoodWe battery inverter's vendor controller with a local one: holds net grid exchange at zero by emulating the inverter's smart meter over RS485, and runs the monthly battery maintenance cycle the vendor box was doing.

repository.yaml            add-on repository metadata
goodwe_controller/         the add-on
  config.yaml              manifest + options schema (the per-site config form)
  app/                     the controller
    control.py             the control law — pure functions, no I/O
    maintenance.py         the monthly cycle state machine
    hass.py                Supervisor/Core API access
    store.py               persistent state in /data
    mqtt.py                optional status entities
    web.py                 ingress UI
    main.py                orchestration, heartbeat, failsafe behaviour
  test_control.py          runnable checks — no framework needed
  test_maintenance.py      runnable checks — walks a full cycle in fake time
  DOCS.md                  the add-on's documentation tab
firmware/goodwe-master.yaml  ESPHome config for the T-CAN485
estop/rs485_log.py           optional RS485 e-stop / bus witness
docs/GoodWe-RS485-Field-Guide.pdf  the guide techs carry (10pp, A4)
docs/build_guide.py          its single source - rebuilds the HTML and PDF
FIELD-GUIDE.md             how to edit and rebuild the guide

Install

Settings → Add-ons → Add-on store → ⋮ → Repositories → add this repository's URL, then install GoodWe RS485 Controller.

Requires Home Assistant OS or Supervised. Add-ons cannot be installed on HA Container or Core.

Read this first

The inverter holds its last command forever. It has no meter-timeout of its own — a controller that dies mid-command leaves the battery running until a human intervenes. Measured on real hardware: 5 kW of discharge held for 113 seconds after a controller went silent.

Three layers exist because of that, and only the third covers the Home Assistant machine itself dying:

1. ESP32 watchdog — no fresh setpoint for ~30 s → command 0 W, and keep commanding it.
2. Wind-down before firmware updates — 0 W written before the update starts.
3. RS485 e-stop (optional) — writes 0 W after 30 s of total bus silence.

Sites sold without the e-stop must have the acknowledgement in FIELD-GUIDE.md §10 signed.

Development

The control law and the maintenance machine are pure Python with no Home Assistant imports, so they run anywhere:

cd goodwe_controller
python3 test_control.py
python3 test_maintenance.py

Both must pass before shipping any change. They are not unit-test theatre — each assertion corresponds to a rule whose absence produced an observed failure on real hardware, and the comments in control.py say which.

Compatibility

Check the serial number, not the model name. Characters 6-8 of the serial are the platform tag:

tag	platform	verdict
ESU EMU ESA BPS BPU EMJ IJL	105 — ES/EM/BP, AA55-era meter bus	supported
SPB SPN	745 — SBP G2 (GW…-SBP-20)	no
ESN ESC	745 — ES G2 (GW…-ES-20)	no
ETU EHU BTU …	205/745/753 — ET/EH/BT hybrids	no
SDT DST MSU NSU …	PV-only inverters — no battery to control	no

A "-20" or "G2" suffix means a different platform with a different meter protocol. The tags come from the goodwe library's PLATFORM_105_MODELS, which is also what Home Assistant's own integration uses to pick a protocol.

• GoodWe ES / BP family inverters (AA55 / RS485 meter-bus generation)
• The protocol is reverse-engineered. There is no vendor contract, and a firmware change on GoodWe's side could break every installation at once. Say so when you sell it.