Add optional arguments temperature_ref and irradiance_ref to pvsystem.sapm

[RDaxini]

• Closes Add reference temperature and irradiance as optional parameters to pvsystem.sapm #2432
• I am familiar with the contributing guidelines
• Tests added
• Updates entries in docs/sphinx/source/reference for API changes.
• Adds description and name entries in the appropriate "what's new" file in docs/sphinx/source/whatsnew for all changes. Includes link to the GitHub Issue with :issue:`num` or this Pull Request with :pull:`num`. Includes contributor name and/or GitHub username (link with :ghuser:`user`).
• New code is fully documented. Includes numpydoc compliant docstrings, examples, and comments where necessary.
• Pull request is nearly complete and ready for detailed review.
• Maintainer: Appropriate GitHub Labels (including remote-data) and Milestone are assigned to the Pull Request and linked Issue.

Related: #825

[echedey-ls]

I'm unsure about the reference names here, no strong opinion.
Anyway, as always, good work @RDaxini.

[echedey-ls]

Suggested change

	def sapm(effective_irradiance, temp_cell, module, reference_temperature=25,
	def sapm(effective_irradiance, temp_cell, module, *, reference_temperature=25,

Consider using kwarg-only parameters to enforce readability of code. For future issues debugging, ...
Completely optional suggestion, it's not a common trend in pvlib.

[RDaxini]

I'm not familiar with what this is doing actually... could you elaborate or forward a link for me to review?
You noted it's optional / uncommon in pvlib currently, so I'll just let others comment whether to go ahead with this as I have no idea 😅

[echedey-ls]

Quick lookup on the internet and you will have a ton of information more extensive, but here is a short example, where all statements are expected to print Hola Dax. The star means the following arguments are only allowed to be passed in as keyword-only (parameter_name=value):

def hola_dax(greet, name):
    print(f"{greet} {name}")

# allowed uses
hola_dax("Hola", "Dax")
hola_dax("Hola", name="Dax")
hola_dax(greet="Hola", name="Dax")
hola_dax(name="Dax", greet="Hola")

# however
def hola_dax(greet, *, name):
    print(f"{greet} {name}")
# only allows using the forms:
hola_dax("Hola", name="Dax")
hola_dax(greet="Hola", name="Dax")
# this raises an error:
hola_dax("Hola", "Dax")  # TypeError: hola_dax() takes 1 positional argument but 2 were given

# and the form
def hola_dax(*, greet, name):
    print(f"{greet} {name}")
# only allows:
hola_dax(greet="Hola", name="Dax")
hola_dax(name="Dax", greet="Hola")

This way, you can always enforce people to make readable code.

[RDaxini]

Right ok got it! Seems like a good suggestion to me. Thanks @echedey-ls

[RDaxini]

https://pvlib-python--2434.org.readthedocs.build/en/2434/reference/generated/pvlib.pvsystem.sapm.html#pvlib.pvsystem.sapm
Should * show here in the function, and if so is there any need to document that below in the parameter descriptions...?

[echedey-ls]

LGTM :)
Minor rendering issue in the whatsnew down below.

[kandersolar]

Thanks @RDaxini!