Defines ir_down as weather variable Within faiman_rad.

Author: ramaroesilva

pvlib/pvsystem.py

@@ -414,7 +414,7 @@ def get_iam(self, aoi, iam_model='physical'):
 
     @_unwrap_single_value
     def get_cell_temperature(self, poa_global, temp_air, wind_speed, model,
-                             effective_irradiance=None):
+                             effective_irradiance=None, ir_down=None):
         """
         Determine cell temperature using the method specified by ``model``.
 
@@ -437,6 +437,10 @@ def get_cell_temperature(self, poa_global, temp_air, wind_speed, model,
         effective_irradiance : numeric or tuple of numeric, optional
             The irradiance that is converted to photocurrent in W/m^2.
             Only used for some models.
+            
+        ir_down: numeric, optional
+            Downwelling infrared radiation from the sky, measured on a 
+            horizontal surface in W/m^2. Only used in ``'faiman_rad'`` model.
 
         Returns
         -------
@@ -460,14 +464,16 @@ def get_cell_temperature(self, poa_global, temp_air, wind_speed, model,
         # Not used for all models, but Array.get_cell_temperature handles it
         effective_irradiance = self._validate_per_array(effective_irradiance,
                                                         system_wide=True)
+        ir_down = self._validate_per_array(ir_down, system_wide=True)
 
         return tuple(
             array.get_cell_temperature(poa_global, temp_air, wind_speed,
-                                       model, effective_irradiance)
-            for array, poa_global, temp_air, wind_speed, effective_irradiance
+                                       model, effective_irradiance, ir_down)
+            for array, poa_global, temp_air, wind_speed, effective_irradiance,
+            ir_down
             in zip(
                 self.arrays, poa_global, temp_air, wind_speed,
-                effective_irradiance
+                effective_irradiance, ir_down
             )
         )
 
@@ -1205,7 +1211,7 @@ def get_iam(self, aoi, iam_model='physical'):
             raise ValueError(model + ' is not a valid IAM model')
 
     def get_cell_temperature(self, poa_global, temp_air, wind_speed, model,
-                             effective_irradiance=None):
+                             effective_irradiance=None, ir_down=None):
         """
         Determine cell temperature using the method specified by ``model``.
 
@@ -1229,6 +1235,10 @@ def get_cell_temperature(self, poa_global, temp_air, wind_speed, model,
             The irradiance that is converted to photocurrent in W/m^2.
             Only used for some models.
 
+        ir_down: numeric, optional
+            Downwelling infrared radiation from the sky, measured on a 
+            horizontal surface in W/m^2. Only used in ``'faiman_rad'`` model.
+
         Returns
         -------
         numeric
@@ -1271,7 +1281,8 @@ def get_cell_temperature(self, poa_global, temp_air, wind_speed, model,
             optional = _build_kwargs(['u0', 'u1'],
                                      self.temperature_model_parameters)
         elif model == 'faiman_rad':
-            func = temperature.faiman_rad
+            func = functools.partial(temperature.faiman_rad,
+                                     ir_down=ir_down)
             required = ()
             optional = _build_kwargs(['ir_down', 'u0', 'u1',
                                       'sky_view', 'emissivity'],

tests/test_pvsystem.py

@@ -502,14 +502,15 @@ def test_PVSystem_faiman_rad_celltemp(mocker):
     sky_view = 1.0
     emissivity = 0.88
 
-    temp_model_params = {'ir_down': ir_down, 'u0': u0, 'u1': u1,
-                         'sky_view': sky_view, 'emissivity': emissivity}
+    temp_model_params = {'u0': u0, 'u1': u1, 'sky_view': sky_view,
+                         'emissivity': emissivity}
     system = pvsystem.PVSystem(temperature_model_parameters=temp_model_params)
     mocker.spy(temperature, 'faiman_rad')
     temps = 25
     irrads = 1000
     winds = 1
-    out = system.get_cell_temperature(irrads, temps, winds, model='faiman_rad')
+    out = system.get_cell_temperature(irrads, temps, winds, ir_down,
+                                      model='faiman_rad')
     temperature.faiman_rad.assert_called_once_with(irrads, temps, winds,
                                                    ir_down, u0, u1,
                                                    sky_view, emissivity)