Remove empty horizon brightening component from haydavies

Author: cbcrespo

pvlib/irradiance.py

@@ -797,8 +797,7 @@ def haydavies(surface_tilt, surface_azimuth, dhi, dni, dni_extra,
             * poa_sky_diffuse: Total sky diffuse
             * poa_isotropic
             * poa_circumsolar
-            * poa_horizon (always zero, not accounted for by the
-              Hay-Davies model)
+        The model does not support a horizon brightening component.
 
     Notes
     ------
@@ -862,8 +861,6 @@ def haydavies(surface_tilt, surface_azimuth, dhi, dni, dni_extra,
         # Calculate the individual components
         diffuse_components['poa_isotropic'] = poa_isotropic
         diffuse_components['poa_circumsolar'] = poa_circumsolar
-        diffuse_components['poa_horizon'] = np.where(
-            np.isnan(diffuse_components['poa_isotropic']), np.nan, 0.)
 
         if isinstance(sky_diffuse, pd.Series):
             diffuse_components = pd.DataFrame(diffuse_components)

tests/test_irradiance.py

@@ -209,13 +209,11 @@ def test_haydavies(irrad_data, ephem_data, dni_et):
 
 
 def test_haydavies_components(irrad_data, ephem_data, dni_et):
-    keys = ['poa_sky_diffuse', 'poa_isotropic', 'poa_circumsolar',
-            'poa_horizon']
+    keys = ['poa_sky_diffuse', 'poa_isotropic', 'poa_circumsolar']
     expected = pd.DataFrame(np.array(
         [[0, 27.1775, 102.9949, 33.1909],
          [0, 27.1775, 30.1818, 27.9837],
-         [0, 0, 72.8130, 5.2071],
-         [0, 0, 0, 0]]).T,
+         [0, 0, 72.8130, 5.2071]]).T,
         columns=keys,
         index=irrad_data.index
     )