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export_price_eur_kwh() modelled injection as one scalar. Eneco publishes 0,1 x BELPEX-H - 1,188 on the same card as its consumption formula, identical on the January and September 2026 cards; ENGIE publishes (B x eSpot_15) - A; Aspiravi uses 0,07 against ~0,10 on its own consumption leg. Reproduced against the shipped readers over one real BELPEX day: the published formula gives 24 distinct prices with a spread of 0.16710 EUR/kWh, the scalar gives 0.00000, and 5 of 24 hours are NEGATIVE - down to -0.03008 EUR/kWh - which are the midday hours a PV household exports in. The 6% VAT asymmetry is not wrong in the scalar, it is unstateable. THE CARD'S BEFORE-STATE WAS WRONG AND THE AGENT CORRECTED IT. I wrote that this affects what the operator is shown. It did not: export_price_eur_kwh() had ZERO callers under app/ - not arbitrage, not the status page, not MQTT. Verified independently before merge; the only references are its own definition, the defaults entry, FRAMEWORK_KEYS and two comments. So the honest before-state is weaker than the card claimed: the scalar was not a misleading display, it was an UNREAD OPTION. DOCS, CHANGELOG and the startup line say so, and a check grades it. An operator actually seeing their injection price is a separate ticket. Machinery reused rather than copied, which is TARIFF-17's move applied a second time: parse_export_formula() is parse_price_formula() with ONE argument moved, selecting a row of a _LEGS table, so everything that differs between the legs is a string and the units table, NaN rule, closed enumerations, unknown-key refusal, card comparison and DST handling are one implementation. Pinned by a check that parses every file under app/ and asserts all 32 grammar names are defined in exactly one module, plus an AST pin on the wrapper's body, plus twelve refusal sentences DERIVED from the consumption leg's own. A NEGATIVE INJECTION PRICE IS ACCEPTED AND AN IMPLAUSIBLE ONE IS STILL REFUSED, and the bound had to move to achieve it: implausible_all_in() floors consumption at +0.02 EUR/kWh of energy, which is fatal on a leg that is legitimately negative. The bound is now off the PRICE and onto the COEFFICIENTS, where it is index-free and sign-free - a pass-through band (0.10-10x; Eneco 1.00x, Aspiravi 0.70x) and an offset-magnitude bound (0.20 against published 0.01188 and 0.02). One spec is put through both bands and the answers printed: the consumption band refuses -0.03008, the injection band accepts it. The missing printed estimate is stated, not worked around. Eneco's injection line has no worked example beside it, so `card` is optional on this leg and unchanged on the other; where an estimate exists the self-check runs at the same tolerance, and where it does not validate.py logs that the coefficients are UNGRADED and names the two bounds that ran instead. A check MEASURES the resulting gap: a factor of 0.070 where the contract says 0.100 - 30% of every export payment - passes both bounds, because 0.70x is a pass-through somebody really publishes. The scalar path is genuinely unchanged: the function body is pinned on the AST and seven option dicts are compared against the pre-TARIFF-16 expression with ==. Evidence: 29/29 green, CI green. Twenty mutations, every one red on a named check. Giving the injection band TARIFF-15's floor is red in test_price.py and GREEN IN THE OTHER 28 FILES; so are the second-grammar and ignore-the-formula mutants. One is a single byte, one is ZERO bytes and moves no decision - legs transposed in the VAT banner, caught by an ordered-pair check. One is recorded for its SHAPE rather than its result: rerouting the scalar through the seam recurses, so the suite dies naming nothing, and a second mutation of the same property exists so a check can name it. Two sharp edges flagged rather than smoothed: `index` and `resolution` on the injection leg name a series nobody fetches, which an operator could misread as a promise to fetch it; and the coefficient bands are materially weaker than a card check, catching the factor-of-10 class and nothing else.
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 — routes only, status and configuration
config_page.py the configuration page's markup, style and script
configui.py its field model, built from the Supervisor's own
schema + translations — owns no key, label or rule
selfconfig.py reading and writing this add-on's own options,
with the validate-first / compare-and-swap gate
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
tools/supervisor_selfapi_probe.py what the Supervisor really permits and
returns, run against its own release image
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.