diff --git a/docs/sphinx/source/whatsnew/v0.16.2.rst b/docs/sphinx/source/whatsnew/v0.16.2.rst
index 64132a2547..2acc24384b 100644
--- a/docs/sphinx/source/whatsnew/v0.16.2.rst
+++ b/docs/sphinx/source/whatsnew/v0.16.2.rst
@@ -7,7 +7,6 @@ v0.16.2 (Anticipated December, 2026)
 Breaking Changes
 ~~~~~~~~~~~~~~~~
 
-
 Deprecations
 ~~~~~~~~~~~~
 
@@ -28,6 +27,12 @@ Enhancements
   allowing for choosing between ERA5 and ERA5-Land datasets.
   (:pull:`2780`)
 
+* Pass ``offset`` directly to ``_calculate_simple_day_angle`` in
+  :py:func:`pvlib.solarposition.equation_of_time_pvcdrom` and
+  :py:func:`pvlib.solarposition.declination_cooper69` instead of
+  adding or subtracting equivalent multiples of 2*pi/365 afterwards.
+  (:issue:`2902`, :pull:`2911`)
+
 Documentation
 ~~~~~~~~~~~~~
 * Clarified in :py:func:`pvlib.tracking.singleaxis` that the tracker
diff --git a/pvlib/solarposition.py b/pvlib/solarposition.py
index 4441ed01f1..2974ffc8d3 100644
--- a/pvlib/solarposition.py
+++ b/pvlib/solarposition.py
@@ -1144,8 +1144,7 @@ def equation_of_time_pvcdrom(dayofyear):
     equation_of_time_spencer71
     """
     # day angle relative to Vernal Equinox, typically March 22 (day number 81)
-    bday = \
-        _calculate_simple_day_angle(dayofyear) - (2.0 * np.pi / 365.0) * 80.0
+    bday = _calculate_simple_day_angle(dayofyear, offset=81)
     # same value but about 2x faster than Spencer (1971)
     return 9.87 * np.sin(2.0 * bday) - 7.53 * np.cos(bday) - 1.5 * np.sin(bday)
 
@@ -1236,8 +1235,8 @@ def declination_cooper69(dayofyear):
     --------
     declination_spencer71
     """
-    day_angle = _calculate_simple_day_angle(dayofyear)
-    dec = np.deg2rad(23.45 * np.sin(day_angle + (2.0 * np.pi / 365.0) * 285.0))
+    day_angle = _calculate_simple_day_angle(dayofyear, offset=-284)
+    dec = np.deg2rad(23.45 * np.sin(day_angle))
     return dec