Fix PVSystem module_type docstring default (pvlib#2713)

* Fix PVSystem module_type docstring default

* Fix docstring references in v0.15.1 release notes

Updated issue and pull request references for clarity.

* Update docs/sphinx/source/whatsnew/v0.15.1.rst

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

* Update pvlib/pvsystem.py

Co-authored-by: Echedey Luis <80125792+echedey-ls@users.noreply.github.com>

* Apply suggestion from @RDaxini

Co-authored-by: Rajiv Daxini <143435106+RDaxini@users.noreply.github.com>

---------

Co-authored-by: Cliff Hansen <cwhanse@sandia.gov>
Co-authored-by: Echedey Luis <80125792+echedey-ls@users.noreply.github.com>
Co-authored-by: Rajiv Daxini <143435106+RDaxini@users.noreply.github.com>

Author: 4 people

docs/sphinx/source/whatsnew/v0.15.1.rst

@@ -40,6 +40,9 @@ Documentation
 * Add AI checkbox to PR template, and auto-generate a comment on PRs
   from first-time contributors regarding AI and contributing guidelines.
   (:issue:`2617`, :pull:`2624`)
+* Update :py:class:`pvlib.pvsystem.PVSystem` docstring to state that
+  ``module_type`` is optional.
+  (:issue:`2634`, :pull:`2713`)
 * Fix a broken docstring reference to ``grounddiffuse`` in
   :py:func:`pvlib.irradiance.poa_components`
   (:issue:`2089`, :pull:`2708`)

pvlib/pvsystem.py

@@ -140,7 +140,7 @@ class PVSystem:
     module : string, optional
         The model name of the modules.
 
-    module_type : string, default 'glass_polymer'
+    module_type : string, optional
          Describes the module's construction. Valid strings are 'glass_polymer'
          and 'glass_glass'. Used for cell and module temperature calculations.