first_solar_spectral_correction deprecation points to a non-existent alternative

[cwhanse]

Describe the bug

This line points calls to pvlib.atmosphere.first_solar_spectral_correction to pvlib.spectrum.spectral_factor_firstsolar which doesn't exist. The deprecation should point to pvlib.spectrum.mismatch.spectral_factor_firstsolar

Versions:

• pvlib.__version__: 0.10.1

[ai-naymul]

Hey I would like to work on this issue, may I?

[cwhanse]

@ai-naymul yes, please!

[kandersolar]

It's true that spectral_factor_firstsolar lives in pvlib/spectrum/mismatch.py, but the spectrum __init__.py file imports it into the pvlib.spectrum namespace: https://github.com/pvlib/pvlib-python/blob/main/pvlib/spectrum/__init__.py#L7

So the function is indeed accessible with pvlib.spectrum.spectral_factor_firstsolar:

In [133]: pvlib.spectrum.spectral_factor_firstsolar
Out[133]: <function pvlib.spectrum.mismatch.spectral_factor_firstsolar(precipitable_water, airmass_absolute, module_type=None, coefficients=None, min_precipitable_water=0.1, max_precipitable_water=8)>

This is also the name that is used in the docs: https://pvlib-python.readthedocs.io/en/stable/reference/generated/pvlib.spectrum.spectral_factor_firstsolar.html

So I think it makes sense to leave the deprecation message as-is.

[cwhanse]

OK, my mistake. I don't quite grok how that import works and couldn't find the function when I was looking for it.