glenn schrooyenandClaude Opus 5
9aed43990b
The stale-input watchdog asks whether the meter is still talking. The saturation freeze asks whether the inverter can follow. The output clamp asks whether the number is too big. A loop can pass all three while charging the battery out of the grid, because the only thing wrong is the sign. On 2026-08-20 a commercial controller did exactly that four times in one day, for up to 77 minutes at a stretch, reaching a commanded -14 768 W against a ±5000 W inverter. app/watchdog.py compares the emitted setpoint against the authoritative P1 figure and, when they oppose each other with both over 300 W for 180 s continuously, files a failsafe SET claim at P_SAFETY, commands 0 W and latches there until an operator starts control again. Validated against that day rather than against an argument: sim/replay_sign.py in the infra repo drives this module over the committed captures of both 2026-08-20 and the healthy 2026-08-23 and reaches 18 trips on the fault day - every one inside a window NOTES.md §4.7 accounts for - and 0 on the healthy day. The four episodes do share one signature: 0.3 / 0.9 / 10.5 / 0.0 % sign agreement inside them against 92.9 % healthy. Three decisions the ticket could not make: - It is DISARMED whenever the grid-following loop is not what is driving. Sign agreement is a property of a loop that follows the meter, and a maintenance grid charge opposes the meter by design - 2500 W of charge into a house drawing 500 W is +3000 W on the meter against a -2500 W command, for hours. The gate tests the emitted number, not the winning claim's name, because a limit claim can let the loop "win" and still replace its value. - The trip LATCHES. Commanding 0 W removes the command side of the comparison, so the disagreement always clears the moment the trip works. - sign_disagree_w at or above max_w is refused at startup. The arbiter never lets a command exceed max_w, so such a threshold leaves the watchdog incapable of firing while the status page still reports it armed. What it does not catch, said out loud: an inverter that ACTS opposite to its command moves the meter further the same way, leaving command and meter in agreement. That is the saturation freeze's job. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01Du77usMj8XNKNFZGmUiWDa
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
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. 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.