placeholder unit tests, some documentation fixes.

Author: stephenjkaplan

pvlib/temperature.py

@@ -676,14 +676,14 @@ def _calculate_radiative_heat(module_area, view_factor, emissivity,
 
     emissivity : float
         # TODO there are probably 2 of these values
-        Thermal emissivity [unitless]
+        Thermal emissivity [unitless]. Must be between 0 and 1.
 
     temperature1 : float
-        Temperature of object 1 [C]
+        Temperature of object 1 [K]
 
     temperature2 : float
 
-        Temperature of object 2 [C]
+        Temperature of object 2 [K]
     Returns
     -------
     q : float
@@ -745,11 +745,12 @@ def hayes(poa_effective, temp_air, wind_speed, module_efficiency, module_area,
         module would be in steady-state equilibrium with the environment
 
     emissivity_sky : float, default 0.95
-        Thermal emissivity of sky [unitless].
+        Thermal emissivity of sky [unitless]. Must be between 0 and 1.
 
     emissivity_ground : float, default 0.85
         Thermal emissivity of ground [unitless]. Default value is suggested
-        value for sand. Suggested value for grass is 0.9.
+        value for sand. Suggested value for grass is 0.9. Must be between
+        0 and 1.
 
     k_c : float, default 12.7
         Free convective heat coefficient. Defaults to value for "hot"
@@ -823,6 +824,7 @@ def hayes(poa_effective, temp_air, wind_speed, module_efficiency, module_area,
             temperature1=t_mod_i,
             temperature2=t_sky
         )
+        # TODO paper indicates temps equal, but that yields zero q
         q_mod_ground = _calculate_radiative_heat(
             module_area=module_area,
             view_factor=view_factor_mod_ground,

pvlib/tests/test_temperature.py

@@ -190,3 +190,21 @@ def test_fuentes(filename, inoct):
     night_difference = expected_tcell[is_night] - actual_tcell[is_night]
     assert night_difference.max() < 6
     assert night_difference.min() > 0
+
+
+def test__calculate_radiative_heat():
+    # TODO placeholder until final model is validated
+    q = temperature._calculate_radiative_heat(
+        module_area=2.47,
+        view_factor=0.5,
+        emissivity=0.5,
+        temperature1=30 + 273.15,
+        temperature2=10 + 273.15
+    )
+    assert round(q, 5) == 70.65021
+
+
+def test_hayes():
+    # TODO placeholder until final model is validated
+    pass
+