fix battery charge u self_sustain rezimu

backend/tests/test_control_exporter_tou.py

@@ -123,6 +123,26 @@ class DeyeTouParamsTests(unittest.TestCase):
         self.assertTrue(g)
         self.assertEqual(s, 95)
 
+    def test_self_sustain_tou_stays_min_soc_even_if_sell_negative(self) -> None:
+        """SELF_SUSTAIN: nízké TOU (min_soc), ne 100 % z negativní vykupní — LP se nepoužívá."""
+        sp = ControlSetpoints(
+            battery_w=None,
+            grid_export_limit=0,
+            ev1_current_a=0,
+            ev2_current_a=0,
+            heat_pump_enable=False,
+            grid_setpoint_w=0,
+            ev1_power_w=0,
+            ev2_power_w=0,
+            target_soc_pct=None,
+            effective_sell_price_czk_kwh=-0.48,
+            self_sustain_local_use=True,
+        )
+        self.assertEqual(get_deye_mode(sp), "PASSIVE")
+        _p, s, g = _deye_tou_params(sp, _inv(min_soc=12, reserve_soc=20))
+        self.assertFalse(g)
+        self.assertEqual(s, 12)
+
     def test_lock_battery_uses_min_soc(self) -> None:
         sp = ControlSetpoints(
             battery_w=0,