OPT-17: the solar forecast can come from several entities, summed

New list options pv_forecast_entities and pv_forecast_tomorrow_entities
(same shape as pv_entities); the single-entity keys are unchanged.

- Each member is read in its own unit (Wh/kWh/MWh) in one gather and the
  day is summed. Hourly splits are merged when every member has one, else
  the total goes on the bell.
- A member missing, unavailable, stale, non-energy or bad makes that
  day's forecast unusable (no partial sum). A caution row names it by
  position; the action log names the entity once per change.
- Single key and list both set for one day: refused at start.
- A one-member list behaves exactly like the single key (test_opt17.py);
  the single-key path is byte-identical to e36565f over 24 scenarios.
- Supervisor shape measured: tools/supervisor_shape_probe.py section J.

DECISIONS/OPT-17-several-forecast-entities.md has the rules.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Bdqr7PiaHcBnzPituu2yTC

goodwe_controller/DOCS.md

@@ -186,6 +186,8 @@ The label and description each setting shows on the Configuration tab, in tab or
 | Hardware | Battery modes | `battery_modes_enabled` | Give each battery an on and off switch and a mode, set on the Batteries screen. |
 | Hardware | Solar forecast, today (kWh) | `pv_forecast_entity` | Optional. A forecast sensor with today's remaining solar energy, such as Forecast.Solar or Solcast. A battery then buys only what the sun will not give. |
 | Hardware | Solar forecast, tomorrow (kWh) | `pv_forecast_tomorrow_entity` | Optional. The same forecast for tomorrow. It helps plan a cheap hour before midnight. |
+| Hardware | Several solar forecasts, today (kWh) | `pv_forecast_entities` | Optional. One row per forecast sensor, such as one per inverter, used instead of the single one above. They are added up. |
+| Hardware | Several solar forecasts, tomorrow (kWh) | `pv_forecast_tomorrow_entities` | Optional. The same list for tomorrow. If one sensor has no reading, that day's forecast is not used. |
 | Hardware | Trust in the forecast (%) | `solar_trust_pct` | Forecasts are often too sunny. At 70 % the add-on plans with 7 of every 10 kWh forecast. |
 | Hardware | Solar production entity (W) | `pv_entity` | Optional. Your solar inverter's power sensor, positive while producing. The add-on records it and does not use it for control. |
 | Hardware | Solar production entities, per inverter (W) | `pv_entities` | Optional. Use one row per solar inverter instead of “Solar production entity” when you have several. If one stops reporting, no total is recorded. |
@@ -539,6 +541,9 @@ With battery modes on, these choices replace the *Charging and selling on price*
 - With no prices, or too small a gap, every battery follows the house.
 
 **Solar forecast** (`pv_forecast_entity`, optional). A Home Assistant sensor with the solar energy still to come today, in kWh. These work: Forecast.Solar (`sensor.energy_production_today_remaining`), Solcast PV Forecast (`sensor.solcast_pv_forecast_forecast_remaining_today`) and Open-Meteo Solar Forecast (`sensor.energy_production_today_remaining`). Set `pv_forecast_tomorrow_entity` to the matching *tomorrow* sensor to plan a cheap run before midnight.
+- **Several forecasts.** If your forecast comes as several sensors (one per inverter or roof side), list them in `pv_forecast_entities` and, for tomorrow, `pv_forecast_tomorrow_entities`, instead of the single key. They are added up, each in its own unit (Wh, kWh or MWh). Set the list or the single key for a day, not both.
+- If one of them has no reading, is stale or is not in an energy unit, that day's forecast is not used at all. A part of the sun is not counted as all of it. The status page names the source by its place in the list.
+- The hourly shape is kept only if every sensor has one. Otherwise the total is spread over the day as for Forecast.Solar.
 - Before each cheap run the add-on asks: will the sun fill the batteries before the expensive hours? It counts on `solar_trust_pct` of the forecast (70 %), less what the house uses. Solar first batteries get that sun first.
 - *Leftover solar* then charges from the grid only the shortfall: what the house will draw from it in the expensive hours, less its share of the sun. Not up to the top level.
 - *Cheap hours only* ignores the forecast and fills to the top level.