# OPT-11 - battery modes, per battery

A battery's mode (on/off, Solar first, Leftover solar) is a soft unit limit at
`P_MODE` = 35 that always holds 0 W. A SET above 35 (a safety stop) overrides
it; a limit above 35 (the peak guard) makes it give way only as far as that
limit needs, and a battery its mode holds back then carries only what the
others cannot (`arbiter._unit_modes()`, `_site_mode()`). Design and owner answers: `goodwe-session/OPT-11-design.md` (2026-09-27);
P1 is its section 6 P1, and the pull request lists what was measured.

- Off by default (`battery_modes_enabled`); off, commands are byte-identical to
  a5dddad (`test_modes.py` part 1).
- Off is a mode range, so the peak guard can still use an Off battery when the
  others cannot cover the floor (design sections 2-3). Whether Off should be
  absolute is an open owner question.
- Review (PR #149): releasing only when the peak floor bound S let a trade won
  above the floor keep the modes and place less than the floor, and let a
  capped grid charge release an Off battery. Both are graded in
  `test_arbiter.py` part 11. The loop bound leaves a side that reaches the
  rail to the rail, so SAFETY-03 still flags a loop winding into it.
- P2 (HA entities): a select and a switch per battery, only while modes are
  on; commands go through `handle_action()`, the page's path. A retained
  command is dropped, not applied: the store already holds the last choice,
  and a replay after a restart could otherwise undo a newer one. The config
  topics announced are kept in the store (`mqtt_mode_configs`), so turning
  modes off removes exactly those, and an install that never turned them on
  publishes what ed739d4 did (`test_mqtt.py` part 10). A removed topic stays
  in that list and its empty config is re-sent on each start, so a start with
  no broker cannot lose it; re-sending is harmless. The HA options are the
  page's English names, pinned by a test, and are not renamed with the page:
  automations send them.
- In P1 only Off closes a direction; Leftover solar differs by charging last.
- P3 (price runs, `priceruns.py`, `modetrade.py`): each battery's range is
  narrowed by its role this tick (hold, give, charge, rest, sell); main.py
  files the intersection with the switch, so it still holds 0 W. With modes on
  the site trade is filed by the modes, sized from the loop bound (so no
  battery a mode or a refusal holds is asked for watts, P1's unmet share) and
  the guard's headroom; `arbitrage.decide()` runs only with modes off, which
  stays byte-identical to 7a00f12 (`test_modes_p3.py` part 1).
- SAFETY-46 item 2 is decided as the owner answered (2026-09-25): a trade is
  a run of consecutive firm slots. It applies with battery modes on; the
  modes-off trade keeps its one-period shape, because that path must not move.
- Choices that were measured, not assumed (tools/opt11p3_replay.py):
  - a sale needs the guard to have measured the quarter, not to be clear: a
    5 kW discharge alone reads "engaged" on export and flipped the sale every
    5 s;
  - a grid charge makes the others rest, so it starts only at 500 W and, once
    the guard or the headroom stops it, stays off for that 15-minute period
    (without: 13 flips in 4 minutes under a 3.5 kW house);
  - stored energy is valued at the last cheap run for 12 h, and a charge
    needs its own run to clear the spread (without: a night charge was spent
    on flat morning prices, then charging went on at them);
  - a run edge reseeds the loop at the house's level (a 3 kW import spike
    removed; about 0.1 x rating still overshoots as export).
- Replay (tools/opt11p3_replay.py, 16 recorded days, EPEX hourly prices a
  year earlier, modelled batteries), net EUR, lower is better: P2 19.33, P3
  Solar first + Leftover solar 19.57, with a sale 19.60, the old one-period
  trade 18.14. Review of #153 (same model, with a per-action split):
  - the cheapest hours were at midday on 15 of 16 days, so Leftover solar (acting
    as Cheap hours until P4) bought 12.2 kWh there that the sun would have
    given: 7 kWh more exported, 12 kWh less solar stored. Holding for the
    expensive hours saved 4 kWh of import, not enough. With no grid charge on
    Leftover solar: 19.44;
  - the old trade charged one hour, so the afternoon sun still fit;
  - a sale earned the wholesale price (2.27 EUR for 11.4 kWh) and the house
    then bought the same energy back (2.29 EUR): a wash before wear. It pays
    only when the sale hour's wholesale price beats the later import price,
    levies included (about 0.13 EUR/kWh above that hour's wholesale here);
  - valuing the charge left at the end, wear and real Flemish levies make
    selling worse and do not change the order.
- Owner decision 2026-09-29 (option A): selling is off until it can be judged
  on the price the grid pays (`packmode.SELLING_ENABLED`, code kept), and
  Leftover solar takes solar only until P4's forecast
  (`packmode.GRID_CHARGE_MODES`); Cheap hours only still charges from the grid. Replayed
  (16 days, as above): Solar first + Leftover solar 19.44 EUR net against
  P2's 19.33; Solar first + Cheap hours only 19.57.
- Not done in P3: the forecast (P4), and a headroom too short for the run
  moving the rest to the next cheap periods.