add freestanding back in

Author: cwhanse

pvlib/pvsystem.py

@@ -168,9 +168,10 @@ class PVSystem:
         Inverter parameters as defined by the SAPM, CEC, or other.
 
     racking_model : string, optional
-        Valid strings are ``'open_rack'``, ``'close_mount'``, and
-        ``'insulated_back'``. Used to identify a parameter set for the SAPM
-        cell temperature model. See :py:func:`~pvlib.temperature.sapm_module`
+        Valid strings are ``'open_rack'``, ``'close_mount'``,
+        ``'freestanding'``, and ``'insulated_back'`. Used to identify a
+        parameter set for the SAPM cell temperature model.
+        See :py:func:`~pvlib.temperature.sapm_module`
         for definitions.
 
     losses_parameters : dict or Series, optional
@@ -1394,9 +1395,10 @@ class FixedMount(AbstractMount):
         West=270. [degrees]
 
     racking_model : str, optional
-        Valid strings are ``'open_rack'``, ``'close_mount'``, and
-        ``'insulated_back'``. Used to identify a parameter set for the SAPM
-        cell temperature model. See :py:func:`~pvlib.temperature.sapm_module`
+        Valid strings are ``'open_rack'``, ``'close_mount'``,
+        ``'freestanding'``, and ``'insulated_back'`. Used to identify a
+        parameter set for the SAPM cell temperature model.
+        See :py:func:`~pvlib.temperature.sapm_module`
         for definitions.
 
     module_height : float, optional
@@ -1473,10 +1475,10 @@ class SingleAxisTrackerMount(AbstractMount):
         `cross_axis_tilt`. [degrees]
 
     racking_model : str, optional
-        Valid strings are ``'open_rack'``, ``'close_mount'``, and
-        ``'insulated_back'`. Used to identify a parameter set for the SAPM
-        cell temperature model. ``'open_rack'`` should be used for systems
-        with single-axis trackers.
+        Valid strings are ``'open_rack'``, ``'close_mount'``,
+        ``'freestanding'``, and ``'insulated_back'`. Used to identify a
+        parameter set for the SAPM cell temperature model.
+        ``'open_rack'`` should be used for systems with single-axis trackers.
         See :py:func:`~pvlib.temperature.sapm_module` for definitions.
 
     module_height : float, optional