MQTT discovery announced ONE device and hung every entity off one unique_id prefix, so at two inverters B's per-unit telemetry had nowhere to go. It has somewhere now, and not one entity that already exists moved. ⚠️ THE ASYMMETRY IS DELIBERATE. The first roster entry's per-unit rows are announced on THE DEVICE IT ALREADY HAS; every later entry gets its own device, via_device the controller. "One device per inverter" is tidier and is the change that renames every entity on the live install - and because HA keeps the id it composed at FIRST discovery, a rename produces a NEW entity beside a DEAD one: the history stays behind and every dashboard, template and automation naming it goes on pointing at a sensor that quietly stopped updating, including the three live watchdog automations. The composed ids come out symmetric anyway (sensor.goodwe_inverter_a_battery_power / ..._inverter_b_...), so the tidy design's only real benefit is bought here without its cost. * four per-unit rows - setpoint, battery power, SoC, SAFETY-02 sign latch - announced only from a roster of two. At N=1 nothing is announced and nothing is published: no second device, no renamed entity, no added topic. * grid and p1_sample_age_s stay SITE-scoped and are announced ONCE, at every roster length 1-6. One P1, one grid connection, and p1_sample_age_s is a watchdog input - a second copy is a second answer to "is the meter fresh?". * inverter.roster_names() is the one answer to what the units are called, read by build_roster() and by the publisher, which must know the roster before a Controller exists because announcing happens on the CONNACK. * DECISIONS/TEL-07-second-mqtt-device.md records the two designs side by side. VERIFIED BY DIFFING THE ANNOUNCED PAYLOADS, not by reading the code. The release/1.0 baseline in test_mqtt.py was generated by running that commit's module, not transcribed. Roster of one: 9 topics, 0 missing, 0 changed, 0 added. Roster of two: 0 missing, 0 changed, 8 added. MEASURED, NOT ASSERTED. Sixteen mutations through tools/mutation_run.sh; twelve are in the file as a running table, each named with the property it breaks. Three of those properties exist because the table found their ABSENCE - dropping the unit from the state topic, moving `grid` into the per-unit set, and `units=()` in main()'s publisher call were all GREEN on the first run, as was a roster fallback naming two nameless entries `inverter-a`. Part 9 enumerates what the file still cannot see, with sizes. ⚠️ INVERTER B DOES NOT PHYSICALLY EXIST (~2026-09-12). Every roster of two here is SIMULATED, from the datasheet and serial in NOTES.md §1.1b. Nothing about B has been measured and no entity described here has been seen on a broker. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01BwRLw7eKYj2byVdwB6kbjU
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
MUTATION.md how to run a mutation so the result means something
tools/mutation_run.sh the mutation harness - purges bytecode, then grades
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
Picking this up after a break? Read HANDOVER.md first — current state,
what is known broken, and what to do next.
Install
Settings → Add-ons → Add-on store → ⋮ → Repositories → add
https://gittea.kammenstraatha.duckdns.org/admin/goodwe-addon
then install GoodWe RS485 Controller.
⚠️ The repository must be PUBLIC for this to work. Home Assistant clones it
anonymously; against a private repo the store shows nothing and gives no useful
error. If it must stay private, install locally instead: copy
goodwe_controller/ into the machine's /addons/ folder, then
ha store reload — it appears as a Local add-on.
⚠️ Bump version: in goodwe_controller/config.yaml for every change.
Supervisor keys the built image by that version, so without a bump it silently
reuses the old image and your fix appears not to work — on your bench and on
every client's machine.
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:
- ESP32 watchdog — no fresh setpoint for ~30 s → command 0 W, and keep commanding it.
- Wind-down before firmware updates — 0 W written before the update starts.
- 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. To prove a check bites - the way
almost every claim in this repository was established - mutate the module and
run tools/mutation_run.sh, which clears __pycache__ first. It is not
optional: a same-size edit reverted inside one second leaves CPython reusing the
old bytecode, and the run grades code that is not there. goodwe_controller/MUTATION.md
has the mechanism, the measurement, and what the flags do not do. 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.