diff --git a/core/bess/growatt_min_controller.py b/core/bess/growatt_min_controller.py
index 8204e5bf..db10048c 100644
--- a/core/bess/growatt_min_controller.py
+++ b/core/bess/growatt_min_controller.py
@@ -187,7 +187,9 @@ def _group_periods_by_mode(self, start_period: int = 0) -> list[dict]:
 
         for period in range(start_period, num_periods):
             intent = self.strategic_intents[period]
-            mode = self.INTENT_TO_MODE.get(intent, "load_first")
+            mode = self._effective_mode_for_intent(
+                intent, self.INTENT_TO_MODE.get(intent, "load_first")
+            )
 
             if mode != current_mode:
                 # Save previous group if exists
diff --git a/core/bess/growatt_sph_controller.py b/core/bess/growatt_sph_controller.py
index d8227c8e..91260f1f 100644
--- a/core/bess/growatt_sph_controller.py
+++ b/core/bess/growatt_sph_controller.py
@@ -80,6 +80,19 @@ def active_tou_intervals(self) -> list[dict]:
 
     # ── SPH period grouping ───────────────────────────────────────────────────
 
+    def _effective_charge_intents(self) -> frozenset[str]:
+        """Intents that produce an AC charge period, honoring external_solar_mode.
+
+        SOLAR_STORAGE is normally excluded — a DC-coupled SPH charges from
+        its own MPPT without an explicit period.  On AC-coupled PV setups
+        (external_solar_mode) the SPH has no DC solar input, so SOLAR_STORAGE
+        must become an AC charge period or the battery never charges during
+        the planned solar window.
+        """
+        if self.battery_settings.external_solar_mode:
+            return self.CHARGE_INTENTS | {"SOLAR_STORAGE"}
+        return self.CHARGE_INTENTS
+
     def _group_sph_periods(self) -> tuple[list[dict], list[dict]]:
         """Group consecutive strategic intent periods into charge and discharge blocks.
 
@@ -94,7 +107,7 @@ def _group_sph_periods(self) -> tuple[list[dict], list[dict]]:
         discharge_blocks: list[dict] = []
 
         for _category, target_list, intent_set in [
-            ("charge", charge_blocks, self.CHARGE_INTENTS),
+            ("charge", charge_blocks, self._effective_charge_intents()),
             ("discharge", discharge_blocks, self.DISCHARGE_INTENTS),
         ]:
             current_block: dict | None = None
@@ -636,7 +649,7 @@ def log_detailed_schedule(self, header: str = "") -> None:
             is_current = run_start <= current_period <= run_end
             marker = "*" if is_current else " "
 
-            if intent in self.CHARGE_INTENTS:
+            if intent in self._effective_charge_intents():
                 action = "charge"
             elif intent in self.DISCHARGE_INTENTS:
                 action = "discharge"
diff --git a/core/bess/tests/unit/test_external_solar_mode.py b/core/bess/tests/unit/test_external_solar_mode.py
index 50cb1fa5..44bd1b34 100644
--- a/core/bess/tests/unit/test_external_solar_mode.py
+++ b/core/bess/tests/unit/test_external_solar_mode.py
@@ -8,6 +8,8 @@
 
 import pytest
 
+from core.bess.growatt_min_controller import GrowattMinController
+from core.bess.growatt_sph_controller import GrowattSphController
 from core.bess.settings import BatterySettings
 from core.bess.solax_controller import SolaxController
 
@@ -126,3 +128,79 @@ def test_detailed_period_groups_apply_mode_override(self) -> None:
         for group in groups:
             assert group["mode"] == "battery_first"
             assert group["grid_charge"] is True
+
+
+class TestExternalSolarModeGrowattMinTouPath:
+    """The MIN controller's TOU grouping (_group_periods_by_mode) builds the
+    segments actually written to hardware.  It must apply the
+    external_solar_mode override, otherwise SOLAR_STORAGE stays load_first,
+    no TOU segment is created (load_first groups are skipped), and an
+    AC-coupled battery never charges during the solar window.
+    """
+
+    def _controller(self, *, external_solar_mode: bool) -> GrowattMinController:
+        ctrl = GrowattMinController(
+            battery_settings=_settings(external_solar_mode=external_solar_mode)
+        )
+        ctrl.strategic_intents = ["IDLE"] * 40 + ["SOLAR_STORAGE"] * 16 + ["IDLE"] * 40
+        return ctrl
+
+    def test_solar_storage_grouped_as_battery_first_when_enabled(self) -> None:
+        ctrl = self._controller(external_solar_mode=True)
+        groups = ctrl._group_periods_by_mode()
+        modes = [g["mode"] for g in groups]
+        assert "battery_first" in modes
+        solar_group = next(g for g in groups if g["mode"] == "battery_first")
+        assert solar_group["start_period"] == 40
+        assert solar_group["end_period"] == 55
+        assert set(solar_group["intents"]) == {"SOLAR_STORAGE"}
+
+    def test_solar_storage_grouped_as_load_first_when_disabled(self) -> None:
+        ctrl = self._controller(external_solar_mode=False)
+        groups = ctrl._group_periods_by_mode()
+        assert all(g["mode"] == "load_first" for g in groups)
+
+    def test_solar_storage_produces_tou_interval_when_enabled(self) -> None:
+        ctrl = self._controller(external_solar_mode=True)
+        groups = ctrl._group_periods_by_mode()
+        intervals = ctrl._groups_to_tou_intervals(groups)
+        assert len(intervals) == 1
+        assert intervals[0]["batt_mode"] == "battery_first"
+
+    def test_no_tou_interval_when_disabled(self) -> None:
+        ctrl = self._controller(external_solar_mode=False)
+        groups = ctrl._group_periods_by_mode()
+        assert ctrl._groups_to_tou_intervals(groups) == []
+
+
+class TestExternalSolarModeSphChargePeriods:
+    """SPH normally excludes SOLAR_STORAGE from charge periods (a DC-coupled
+    SPH charges from its own MPPT).  With external_solar_mode the SPH has no
+    DC solar input, so SOLAR_STORAGE must produce an AC charge period.
+    """
+
+    def _controller(self, *, external_solar_mode: bool) -> GrowattSphController:
+        ctrl = GrowattSphController(
+            battery_settings=_settings(external_solar_mode=external_solar_mode)
+        )
+        ctrl.strategic_intents = ["IDLE"] * 40 + ["SOLAR_STORAGE"] * 16 + ["IDLE"] * 40
+        return ctrl
+
+    def test_solar_storage_becomes_charge_block_when_enabled(self) -> None:
+        ctrl = self._controller(external_solar_mode=True)
+        charge_blocks, discharge_blocks = ctrl._group_sph_periods()
+        assert len(charge_blocks) == 1
+        assert charge_blocks[0]["start_period"] == 40
+        assert charge_blocks[0]["end_period"] == 55
+        assert discharge_blocks == []
+
+    def test_solar_storage_not_a_charge_block_when_disabled(self) -> None:
+        ctrl = self._controller(external_solar_mode=False)
+        charge_blocks, _ = ctrl._group_sph_periods()
+        assert charge_blocks == []
+
+    def test_grid_charging_still_a_charge_block_when_disabled(self) -> None:
+        ctrl = self._controller(external_solar_mode=False)
+        ctrl.strategic_intents = ["GRID_CHARGING"] * 8 + ["IDLE"] * 88
+        charge_blocks, _ = ctrl._group_sph_periods()
+        assert len(charge_blocks) == 1