Report solar surplus power even when no car is charging

The power sensor now shows effective export whenever the solar surplus
feature is enabled, not only when a car qualifies. This lets automations
for other surplus loads (iBoost, pool pump) use the same signal.

Author: Pezmc

apps/predbat/execute.py

@@ -733,6 +733,7 @@ def detect_car_solar_surplus(self, in_force_export_window):
             self._car_surplus_prev = list(self.car_charging_solar_surplus_active)
             return
 
+        self.car_charging_solar_surplus_power = max(0, self.grid_power)
         surplus_hysteresis = 200  # W deadband to prevent flapping
         # Tolerance for transient battery discharge while surplus is asserted.
         # Distinct from car_charging_solar_surplus_threshold (the user-facing

apps/predbat/tests/test_execute.py

@@ -2589,7 +2589,7 @@ def run_execute_tests(my_predbat):
         battery_power=0,
         assert_status="Demand",
         assert_solar_surplus_active=[False],
-        assert_solar_surplus_power=0,
+        assert_solar_surplus_power=3000,
     )
     if failed:
         return failed
@@ -3032,7 +3032,7 @@ def run_solar_surplus_power_sensor_test(my_predbat):
         print("ERROR: power sensor surplus_active should be True, got {}".format(power_sensor.get("surplus_active")))
         failed = True
 
-    # Now test with no surplus — sensor should publish 0
+    # When car doesn't qualify but there's still export, sensor shows raw export
     failed |= run_execute_test(
         my_predbat,
         "solar_surplus_power_sensor_inactive",
@@ -3044,12 +3044,12 @@ def run_solar_surplus_power_sensor_test(my_predbat):
         battery_power=0,
         assert_status="Demand",
         assert_solar_surplus_active=[False],
-        assert_solar_surplus_power=0,
+        assert_solar_surplus_power=3000,
     )
     power_sensor = my_predbat.ha_interface.dummy_items.get(power_sensor_id, {})
     if isinstance(power_sensor, dict):
-        if power_sensor.get("state") != 0.0:
-            print("ERROR: power sensor state should be 0.0 when inactive, got {}".format(power_sensor.get("state")))
+        if power_sensor.get("state") != 3.0:
+            print("ERROR: power sensor state should be 3.0 (kW) when car inactive, got {}".format(power_sensor.get("state")))
             failed = True
         if power_sensor.get("surplus_active") is not False:
             print("ERROR: power sensor surplus_active should be False when inactive, got {}".format(power_sensor.get("surplus_active")))

docs/car-charging.md

@@ -587,7 +587,7 @@ Enable the feature with these Predbat entities:
 
 - **binary_sensor.predbat_car_charging_slot** gains a `solar_surplus: true` attribute when activated by surplus (rather than a planned charging window).
 - **binary_sensor.predbat_car_charging_solar_surplus** -- Dedicated sensor showing whether surplus charging is currently active.
-- **predbat.car_charging_solar_surplus_power** -- Numeric sensor (kW) showing the effective solar surplus power available for car charging. When surplus is active and the car was charging last cycle, this includes the car's own consumption added back to get the true available export. Useful for automations that adjust charging current proportionally (e.g. `surplus_kw * 1000 / 230 = amps`). Attributes include `threshold` (configured shortfall allowance in W), `battery_power` (current home battery power in kW), and `surplus_active` (boolean).
+- **predbat.car_charging_solar_surplus_power** -- Numeric sensor (kW) showing the effective solar surplus power available. Always reports current export power when the solar surplus feature is enabled, even if no car is currently charging from surplus. When a car was surplus-charging last cycle, the car's own consumption is added back to show the true available export. Useful for automations that adjust charging current proportionally (e.g. `surplus_kw * 1000 / 230 = amps`) or for driving other solar surplus loads (iBoost, pool pump). Attributes include `threshold` (configured shortfall allowance in W), `battery_power` (current home battery power in kW), and `surplus_active` (boolean).
 
 ### Interaction with other settings