diff --git a/tests/solar/test_solar.py b/tests/solar/test_solar.py
index 0959128..bb362b8 100644
--- a/tests/solar/test_solar.py
+++ b/tests/solar/test_solar.py
@@ -25,3 +25,56 @@
 def test_julian_day(date, expected_value):
     v = solar.julian_day(date)
     assert np.isclose(v, expected_value)
+
+
+@pytest.mark.parametrize(
+    "date,expected_value",
+    [
+        (datetime.datetime(2024, 4, 22), (12.235799080498582, 0.40707190497656276)),
+        (
+            datetime.datetime(2024, 4, 22, 12, 0, 0),
+            (12.403019177270453, 0.43253901867797273),
+        ),
+    ],
+)
+def test_solar_declination_angle(date, expected_value):
+    declination, time_correction = solar.solar_declination_angle(date)
+    assert np.isclose(declination, expected_value[0])
+    assert np.isclose(time_correction, expected_value[1])
+
+
+def test_cos_solar_zenith_angle():
+    date = datetime.datetime(2024, 4, 22, 12, 0, 0)
+    latitudes = np.array([40.0])
+    longitudes = np.array([18.0])
+
+    v = solar.cos_solar_zenith_angle(date, latitudes, longitudes)
+    assert np.isclose(v[0], 0.8478445449796352)
+
+
+def test_cos_solar_zenith_angle_integrated():
+    begin_date = datetime.datetime(2024, 4, 22)
+    end_date = datetime.datetime(2024, 4, 23)
+    latitudes = np.array([40.0])
+    longitudes = np.array([18.0])
+
+    v = solar.cos_solar_zenith_angle_integrated(
+        begin_date, end_date, latitudes, longitudes
+    )
+    assert np.isclose(v[0], 0.3110738757)
+
+
+def test_incoming_solar_radiation():
+    date = datetime.datetime(2024, 4, 22, 12, 0, 0)
+    v = solar.incoming_solar_radiation(date)
+    assert np.isclose(v, 4833557.3088814365)
+
+
+def test_toa_incident_solar_radiation():
+    begin_date = datetime.datetime(2024, 4, 22)
+    end_date = datetime.datetime(2024, 4, 23)
+    latitudes = np.array([40.0])
+    longitudes = np.array([18.0])
+
+    v = solar.toa_incident_solar_radiation(begin_date, end_date, latitudes, longitudes)
+    assert np.isclose(v, 1503617.8237746414)