Add Array.get_cell_temperature, PVSystem.get_cell_temperature (#1211)

* add Array.get_cell_temperature and PVSystem.get_cell_temperature, deprecate old PVSystem tcell methods, update ModelChain._set_celltemp

* fix tests

* api.rst

* whatsnew

* add test for invalid model string

* stickler, docs

* nudge to trigger CI

* fix whatsnew

* docstring fix

* try out kinder error messages

* fixing bugs

* test for nice error message

* Update pvlib/pvsystem.py

Co-authored-by: Cliff Hansen <cwhanse@sandia.gov>

* stickler

* Update pvlib/modelchain.py

Co-authored-by: Cliff Hansen <cwhanse@sandia.gov>

* move _build_args to pvlib.tools

* remove deprecated items from api.rst

* def -> partial

* docstring edits

* see also fixes

* remove kwarg nonsense

Co-authored-by: Cliff Hansen <cwhanse@sandia.gov>

Author: kandersolar

docs/sphinx/source/api.rst

@@ -239,11 +239,7 @@ PV temperature models
    temperature.fuentes
    temperature.ross
    temperature.noct_sam
-   pvsystem.PVSystem.sapm_celltemp
-   pvsystem.PVSystem.pvsyst_celltemp
-   pvsystem.PVSystem.faiman_celltemp
-   pvsystem.PVSystem.fuentes_celltemp
-   pvsystem.PVSystem.noct_sam_celltemp
+   pvsystem.PVSystem.get_cell_temperature
 
 Temperature Model Parameters
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^

docs/sphinx/source/whatsnew/v0.9.0.rst

@@ -71,6 +71,16 @@ Deprecations
   * ``ModelChain.weather``
   * ``ModelChain.times``
 
+* The following ``PVSystem`` cell temperature methods have been deprecated
+  and consolidated into the new wrapper method
+  :py:meth:`~pvlib.pvsystem.PVSystem.get_cell_temperature` (:pull:`1211`):
+
+  * :py:meth:`~pvlib.pvsystem.PVSystem.sapm_celltemp`
+  * :py:meth:`~pvlib.pvsystem.PVSystem.pvsyst_celltemp`
+  * :py:meth:`~pvlib.pvsystem.PVSystem.faiman_celltemp`
+  * :py:meth:`~pvlib.pvsystem.PVSystem.fuentes_celltemp`
+  * :py:meth:`~pvlib.pvsystem.PVSystem.noct_sam_celltemp`
+
 * The ``eta_m`` parameter for :py:func:`~pvlib.temperature.pvsyst_cell` is
   replaced by parameter ``module_efficiency``. (:issue:`1188`, :pull:`1218`)
 

pvlib/modelchain.py

@@ -992,12 +992,10 @@ def _set_celltemp(self, model):
 
         Parameters
         ----------
-        model : function
-            A function that takes POA irradiance, air temperature, and
-            wind speed and returns cell temperature. `model` must accept
-            tuples or single values for each parameter where each element of
-            the tuple is the value for a different array in the system
-            (see :py:class:`pvlib.pvsystem.PVSystem` for more information).
+        model : str
+            A cell temperature model name to pass to
+            :py:meth:`pvlib.pvsystem.PVSystem.get_cell_temperature`.
+            Valid names are 'sapm', 'pvsyst', 'faiman', 'fuentes', 'noct_sam'
 
         Returns
         -------
@@ -1009,26 +1007,26 @@ def _set_celltemp(self, model):
         temp_air = _tuple_from_dfs(self.results.weather, 'temp_air')
         wind_speed = _tuple_from_dfs(self.results.weather, 'wind_speed')
         kwargs = {}
-        if model == self.system.noct_sam_celltemp:
+        if model == 'noct_sam':
             kwargs['effective_irradiance'] = self.results.effective_irradiance
-        self.results.cell_temperature = model(poa, temp_air, wind_speed,
-                                              **kwargs)
+        self.results.cell_temperature = self.system.get_cell_temperature(
+            poa, temp_air, wind_speed, model=model, **kwargs)
         return self
 
     def sapm_temp(self):
-        return self._set_celltemp(self.system.sapm_celltemp)
+        return self._set_celltemp('sapm')
 
     def pvsyst_temp(self):
-        return self._set_celltemp(self.system.pvsyst_celltemp)
+        return self._set_celltemp('pvsyst')
 
     def faiman_temp(self):
-        return self._set_celltemp(self.system.faiman_celltemp)
+        return self._set_celltemp('faiman')
 
     def fuentes_temp(self):
-        return self._set_celltemp(self.system.fuentes_celltemp)
+        return self._set_celltemp('fuentes')
 
     def noct_sam_temp(self):
-        return self._set_celltemp(self.system.noct_sam_celltemp)
+        return self._set_celltemp('noct_sam')
 
     @property
     def dc_ohmic_model(self):