Five provider plugins - generic_dayahead, engie_dynamic,
totalenergies_dynamic, eneco_eddy, manual_csv - all emitting exactly
{"prices": [{"start", "eur_per_kwh", "provisional"}]}, tz-aware at the
Brussels offset, EUR/kWh, all-in. Nothing consumes it yet; the seam
lands first, per the PM's ordering.
It is built in goodwe_controller/app/ rather than at specs.md 2.2's
ems/ingest/prices/, per the product owner's decision of 2026-08-30. The
behaviour 9.3 / 8.3 / 11.4 specifies is unchanged.
Three things shape the design, and each is the mechanism rather than a
comment saying to be careful:
Double-counting the markup is unreachable. A plugin does not return a
price - it returns the figure its source published and declares which of
{energy, markup, taxes} that figure already contains. assemble() adds
the complement, once, in the framework. A plugin is never handed
price_markup_eur_kwh: PluginOptions raises FrameworkOption on it, so the
line that adds the margin a second time cannot be written. Engie and
TotalEnergies publish a retail figure with their margin inside; adding
the configured 3 c/kWh on top would have made every arbitrage decision
wrong by that amount with nothing reporting it.
The product type is declared, not inferred from the plugin's name.
eneco_eddy is real-time/imbalance and gets 8.3's widened thresholds
through capabilities().product and volatility_regime(), never through a
name comparison - which is AC2. test_price.py asserts mechanically that
no plugin id appears anywhere in the framework's code, and drives a
sixth provider defined inside the test file to the right regime with
price.py untouched.
"No price data" is a type, not an empty list - the same rework
sim/riglock.py took under TEST-04. A fetch returns PriceRead.series(...)
or PriceRead.no_data(reason), and only the first carries fields. An
empty series is not constructible; no_data has no .points, no .at(), and
.get("points", []) raises rather than returning the default. A day of
free electricity and a day with no prices are different instructions -
arbitrage is pointless under one and forbidden under the other - and an
implementation returning [] cannot tell them apart. Every site-level
failure returns no_data; nothing raises into the control tick.
Also: injection stays a separate scalar (export_price_eur_kwh, AC4),
negative prices survive the boundary validator (17's regression case),
egress is allow-listed against each plugin's own declaration (16), and
no tzdata is used - the shipped Alpine image has none, so Brussels
offsets come from the EU rule and instants are carried as UTC.
validate.py grows rule 7: an unknown provider id, manual_csv with no
path, and - the HA overlap the PM told us to decide about -
price_provider set alongside price_now_entity/price_avg_entity, which is
two price sources where the HA pair silently wins. The HA sensors are
kept and still work alone; TARIFF-03 and OPT-04 are what replace them.
CFG-03 is not widened: the price defaults have ONE in-code mirror,
PRICE_OPTION_DEFAULTS, which validate.py imports rather than restating
and which test_price.py pins to config.yaml by reading the file.
test_price.py is runnable, assert-free in the house style, and every
verdict it prints is derived. It grades the markup arithmetic with
0.031/0.057 rather than the shipped 0.03/0.06, because 0.06 is exactly
twice 0.03 and a degenerate pair would make double-counting
indistinguishable from correct addition - and it asserts that
non-degeneracy as its first section. The DST checks run on the 23-hour
and 25-hour days, not on a normal day where a fixed 24-slot
implementation and a correct one agree. Thirteen mutations were driven
through it; all thirteen go red.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015VXjA3LWccN1rJsk3okyPC
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.