Fix integer truncation in temperature.fuentes by forcing float dtype and update tests

Author: Chirag3841

pvlib/temperature.py

@@ -6,7 +6,6 @@
 import numpy as np
 import pandas as pd
 from pvlib.tools import sind
-from pvlib._deprecation import warn_deprecated
 from pvlib.tools import _get_sample_intervals
 import scipy
 import scipy.constants
@@ -883,7 +882,7 @@ def fuentes(poa_global, temp_air, wind_speed, noct_installed, module_height=5,
     windmod_array = wind_speed * (module_height/wind_height)**0.2 + 1e-4
 
     tmod0 = 293.15
-    tmod_array = np.zeros_like(poa_global)
+    tmod_array = np.zeros_like(poa_global, dtype=float)
 
     iterator = zip(tamb_array, sun_array, windmod_array, tsky_array,
                    timedelta_hours)

tests/test_temperature.py

@@ -501,3 +501,51 @@ def test_glm_repr():
                 "'alpha': 0.9}")
 
     assert glm.__repr__() == expected
+
+
+@pytest.mark.parametrize('tz', [None, 'Etc/GMT+5'])
+def test_fuentes_timezone(tz):
+    index = pd.date_range('2019-01-01', freq='h', periods=3, tz=tz)
+
+    df = pd.DataFrame({'poa_global': 1000, 'temp_air': 20, 'wind_speed': 1},
+                      index)
+
+    out = temperature.fuentes(df['poa_global'], df['temp_air'],
+                              df['wind_speed'], noct_installed=45)
+
+    expected = pd.Series(
+        [48.041843, 51.845471, 51.846428],
+        index=index,
+        name='tmod'
+    )
+
+    assert_series_equal(out.round(6), expected.round(6))
+
+
+def test_fuentes_int_vs_float():
+    """Ensure integer and float inputs give identical results."""
+    index = pd.date_range("2019-01-01", freq="h", periods=2)
+
+    inputs = pd.DataFrame({
+        "poa_global": [1000, 500],
+        "temp_air": [25, 25],
+        "wind_speed": [1, 1],
+    }, index=index)
+
+    result_int = temperature.fuentes(
+        poa_global=inputs["poa_global"],
+        temp_air=inputs["temp_air"],
+        wind_speed=inputs["wind_speed"],
+        noct_installed=45
+    )
+
+    inputs_float = inputs.astype(float)
+
+    result_float = temperature.fuentes(
+        poa_global=inputs_float["poa_global"],
+        temp_air=inputs_float["temp_air"],
+        wind_speed=inputs_float["wind_speed"],
+        noct_installed=45
+    )
+
+    assert_allclose(result_int.values, result_float.values)