Inverter A charging at 3 kW while inverter B discharges at 3 kW nets ~0 W at
P1. The site reads idle while both packs are cycled through two round-trip
conversion losses continuously, for no benefit, and the wear is real.
NOTHING EXISTING CAN SEE IT, AND THAT IS STRUCTURAL. Every guard in this
add-on is a consumer of the NET figure at the grid connection: SAFETY-02's
sign watchdog gates on abs(grid_w) > 300 and the gate never opens at a netted
zero; the peak guard and the capacity tariff both bill grid exchange.
Circulating power is precisely the component of per-inverter power that the
sum destroys, so no threshold on any existing detector could reach it.
WHAT ALLOC-01 ALREADY COVERED, AND IS NOT RE-IMPLEMENTED HERE. Its AC 7
shipped the sign-coherence gate (allocator.REFUSE_SIGN, graded by
test_alloc.py part 6): an allocation whose shares carry two signs is REFUSED,
both units named, no shares returned. That is the COMMAND half - the allocator
can no longer command circulating power. This commit is the MEASUREMENT half:
circulation the allocator NEVER COMMANDED.
app/circulation.py the sensor and the trip
main.py site_circulating_w, the evaluation, the claim, the alarm
arbiter.py `circulation` classified SCOPE_SITE, with the argument
store.py a flat, site-level durable latch
mqtt.py sensor.goodwe_circulating_power
config.yaml two options, two schema ranges, CFG-03 discipline
THE SENSOR: sum(|Bi|) - |sum(Bi)|. Zero when the units pull the same way,
2*min(|Ba|,|Bb|) when they oppose. DERIVED FROM MEASURED PER-INVERTER POWER -
Inverter.batt, register 0x0518 - and never from the allocation record. The
cheap version would be simpler and worth nothing: ALLOC-01's gate already
guarantees the record is sign-coherent, so a record-derived sensor reads zero
BY CONSTRUCTION and can only confirm that the allocator agrees with itself,
which is the third failure mode MUTATION.md names. What this catches is a unit
ignoring or lagging its share, a stale share still being executed, a
maintenance or SAFETY-25 pin holding one unit while the loop drives the other,
or HW-01's power stage running its last instruction for 6 h 25 m with the
comms dead and the allocation record impeccable throughout. batt became
per-instance in DEV-02; before that this could not have been written.
VERIFIED BY MAKING ONE UNIT IGNORE ITS SHARE, on the TEST-19 two-master rig:
S = -2500 W shares a = -1250 W b = -1250 W <- record ok, ONE sign, sums
MEASURED A = -1250 W B = +1000 W <- hardware
sensor over the RECORD : 0 W
sensor over MEASURED power : 2000 W -> trips at 190 s
and the card's own scenario, A -3000 W against B +3000 W at zero house load:
the meter reads +0 W, the sensor reads 6000 W, and the shipped SignWatchdog's
predicate is FALSE on 30 of 30 cycles.
WHAT "ACTED ON" MEANS - decided, and recorded in DECISIONS/. The trip files
Claim.set("circulation", P_SAFETY, 0.0) on the SITE actuator: every inverter
to 0 W, latched. HW-01 established that commanding a wedged inverter achieves
nothing, so the remedy is not aimed at it. A circulating loop needs TWO
participants and one of them is THIS CONTROLLER, faithfully driving the
listening sibling into the one that stopped listening. Stopping (1) halves the
loop, which needs no cooperation from the wedged unit, and (2) - the more
important half - makes the residue VISIBLE at the meter instead of cancelled
at it, where every ordinary guard can finally see it. What it cannot do is
stop the wedged unit; the notification says so and names the isolator as the
last actuator. SITE-scoped because the quantity is defined over the roster and
is identically zero for any one unit - there is no fact of the matter about
which of two opposing inverters is the offender, so filing it per-unit would
invent an attribution and could park the only unit still listening.
THE WINDOW IS FROM THE RIG, NOT A ROUND NUMBER (AC 3). 924 closed-loop runs in
which NOTHING is faulty, over both families of legitimate opposition (7
reversals x 5 write staggers; 7 flap periods x 4 amplitudes), swept across the
whole range the schema accepts for gain and slew_w. Worst CONTINUOUS
legitimate opposition by threshold: 505.0 s at 100 W, 40.0 s at 250 W, 10.0 s
at 300 W, 5.0 s at 400 W and above. The knee is 400 W and it is the schema
floor - below it, ordinary operation holds the sensor over the line for
minutes and no window inside the 900 s billing quarter could tell that from a
fault. circulation_w 700 is 1.75x the knee, the headroom bought for inverter
B's ramp and lag being PLACEHOLDERS until SPIKE-04 measures them.
circulation_hold_s 75 clears three bounds: 15x the worst legitimate episode,
2.5x the firmware's own LINK_STALE_S veto, 12x inside the quarter. A momentary
opposition while one unit slews through zero is LEGITIMATE - writes are
serialised, so B's number lands up to a cycle after A's - and 0 of the 924
runs trip.
THE ALARM SURVIVES AN HA RESTART (SAFETY-34). persistent_notification is in
memory, which is exactly how the 2026-09-02 outage went unseen for 6 h 25 m
with the detector correct throughout. The latch is persisted to /data as flat
site-level keys and the notification is RE-RAISED on the first cycle after
every start, through the same code path as a fresh trip - two paths would be
two chances for the restart one to rot unnoticed.
AT N=1 NOTHING CHANGES (AC 5). |B| - |B| is 0 for every reading including one
nobody took, no claim is ever filed, the arbitration is byte-identical, and
the status page says n/a rather than claiming to watch something that cannot
happen.
VERIFIED BY BREAKING IT (AC 4). 18 mutations, all RED on named checks, each on
a freshly copied tree with no __pycache__ mounted :ro. M10 - the sensor
rewritten to read self.allocation.shares - is the headline: it takes AC 2 red.
Three mutations are +0 B, the risky delta, and are marked as such. One
equivalent mutant (the max(0.0,...) guard) is ARGUED rather than claimed:
searched over 700 000 rosters without a negative. One genuine SURVIVOR was
found and closed - publish() turning an unknown into a published 0 W, the
sensor's own None rule defeated one layer out. Full ledger in DECISIONS/.
arbiter.CLAIM_SCOPE gains its ninth source, so test_peakguard.py's 10f and 10g
tripwires and test_arbiter.py's scope table went red on the line the append
was written. Updated deliberately, with the argument, as their own comments
require. Full 19-file suite green.
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.