From 5ceb21819befab397a2cf1cc68c6a23599e25af3 Mon Sep 17 00:00:00 2001
From: sarankumar <120080287+sarankumar1325@users.noreply.github.com>
Date: Mon, 26 Oct 2026 11:46:21 +0530
Subject: [PATCH] fix(genetic0): keep parameter arrays aligned with the start
 hour on DST days (#1455)

---
 .../optimization/genetic0/genetic0params.py   | 10 ++-
 tests/test_genetic0params_dst.py              | 76 +++++++++++++++++++
 2 files changed, 85 insertions(+), 1 deletion(-)
 create mode 100644 tests/test_genetic0params_dst.py

diff --git a/src/akkudoktoreos/optimization/genetic0/genetic0params.py b/src/akkudoktoreos/optimization/genetic0/genetic0params.py
index b72782da..f03c6269 100644
--- a/src/akkudoktoreos/optimization/genetic0/genetic0params.py
+++ b/src/akkudoktoreos/optimization/genetic0/genetic0params.py
@@ -304,7 +304,15 @@ class Genetic0OptimizationParameters(
         # Add forecast and device data
         interval = to_duration(cls.config.optimization.genetic0.interval_sec)
         power_to_energy_per_interval_factor = cls.config.optimization.genetic0.interval_sec / 3600
-        parameter_start_datetime = ems.start_datetime.set(hour=0, second=0, microsecond=0)
+        # GENETIC0 indexes the parameter arrays by wall-clock hour (the simulation
+        # starts at ``ems.start_datetime.hour``), while the arrays themselves are
+        # sampled in elapsed time. On a DST transition day local midnight is 23 or
+        # 25 elapsed hours away from the same wall-clock hour, so step back
+        # ``hour`` elapsed hours instead of setting the hour to midnight. This keeps
+        # array index ``ems.start_datetime.hour`` aligned with the start slot.
+        parameter_start_datetime = ems.start_datetime.set(second=0, microsecond=0).subtract(
+            hours=ems.start_datetime.hour
+        )
         parameter_end_datetime = parameter_start_datetime.add(hours=cls.config.prediction.hours)
         max_retries = 10
 
diff --git a/tests/test_genetic0params_dst.py b/tests/test_genetic0params_dst.py
new file mode 100644
index 00000000..52ce9eca
--- /dev/null
+++ b/tests/test_genetic0params_dst.py
@@ -0,0 +1,76 @@
+"""GENETIC0 parameter arrays must stay aligned with the start hour on DST days."""
+
+from unittest.mock import AsyncMock, Mock, patch
+
+import numpy as np
+import pandas as pd
+import pendulum
+import pytest
+
+from akkudoktoreos.core.coreabc import get_ems
+from akkudoktoreos.optimization.genetic0.genetic0params import (
+    Genetic0OptimizationParameters,
+)
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize(
+    "start",
+    [
+        # Normal day: 23 elapsed hours since local midnight.
+        pendulum.datetime(2026, 10, 24, 23, tz="Europe/Berlin"),
+        # Fall back (CEST -> CET): 24 elapsed hours since local midnight.
+        pendulum.datetime(2026, 10, 25, 23, tz="Europe/Berlin"),
+        # Spring forward (CET -> CEST): 22 elapsed hours since local midnight.
+        pendulum.datetime(2026, 3, 29, 23, tz="Europe/Berlin"),
+    ],
+    ids=["normal", "fall-back", "spring-forward"],
+)
+async def test_parameter_arrays_start_hour_aligned_on_dst_days(config_eos, start):
+    config_eos.merge_settings_from_dict(
+        {
+            "general": {"timezone": "Europe/Berlin"},
+            "prediction": {"hours": 48},
+            "optimization": {"genetic0": {"horizon_hours": 24}},
+            "feedintariff": {"provider": "FeedInTariffDvhubOnline"},
+            "elecfee": {"provider": None},
+            "devices": {
+                "max_batteries": 0,
+                "max_electric_vehicles": 0,
+                "max_inverters": 0,
+                "max_home_appliances": 0,
+            },
+        }
+    )
+    get_ems().set_start_datetime(start)
+    ems_start = get_ems().start_datetime
+    assert ems_start.hour == 23
+
+    # The tariff is only published from the start slot on, as a live
+    # provider would do late in the evening.
+    prices = pd.Series(
+        np.full(24 * 4, 0.0001),
+        index=pd.date_range(ems_start, periods=24 * 4, freq="15min"),
+    )
+    array_starts = []
+
+    async def read_array(**kwargs):
+        array_starts.append(kwargs["start_datetime"])
+        return np.full(48, 1.0)
+
+    prediction = Mock(
+        update_data=AsyncMock(),
+        key_to_array=AsyncMock(side_effect=read_array),
+        key_to_raw_series=AsyncMock(return_value=prices),
+    )
+    with patch.object(Genetic0OptimizationParameters, "prediction", prediction):
+        parameters = await Genetic0OptimizationParameters.prepare()
+
+    assert parameters is not None
+    # Index ``start.hour`` of every array is the start slot.
+    assert array_starts
+    for array_start in array_starts:
+        assert array_start.add(hours=ems_start.hour) == ems_start
+    tariffs = parameters.ems.feed_in_tariff_per_wh
+    assert isinstance(tariffs, list)
+    assert np.isfinite(tariffs[ems_start.hour : ems_start.hour + 24]).all()