Missing thumbnails in the example gallery

[RDaxini]

Describe the bug
Thumbnails aren't shown for some examples.
What causes this? Is it the fact that the Figures aren't displayed in the example? If so, would this be resolved if I just re-run the notebooks and store the outputs?

To Reproduce
Steps to reproduce the behavior:

1. Go to https://pvlib-python.readthedocs.io/en/stable/gallery/index.html
2. Scroll down to Irradiance transposition and Spectrum sections
3. See error

Expected behavior
Thumbnails of a graph from the example should be displayed

Screenshots

[kandersolar]

What causes this? Is it the fact that the Figures aren't displayed in the example?

Yes, I think so. Figures not being displayed for some reason means sphinx can't grab them to include in the built HTML.

If so, would this be resolved if I just re-run the notebooks and store the outputs?

No, because these aren't notebooks, they're just .py scripts. sphinx executes them de novo during the docs build.

I don't know off the top of my head what the problem is here. I thought .show() would be enough, but it seems otherwise. Nothing sticking out in the logs either.

[echedey-ls]

https://github.com/pvlib/pvlib-python/blob/main/pyproject.toml#L62

sphinx-gallery is not version pinned, gotta look in the changelog. Latest 0.21.0 was released in Apr 24.
https://pypi.org/project/sphinx-gallery/0.21.0/
Previous 0.20.0 was released in 2025-12-02.
Edit to add: no mention of breaking changes in 0.21.0.

I can't debug on mobile, will check later. But we gotta see if thumbnails are being generated and linked correctly.

[echedey-ls]

Frick, the problem is that everything works:

pvlib-python/docs/sphinx/source/conf.py

Lines 391 to 392 in 0f7a205

	# execute only files starting with plot_
	'filename_pattern': 'plot_',

Introduced in #2691

Lucky us with @RDaxini catching that

[echedey-ls]

I suggest adding a explicit prefix or suffix to indicate which files gotta be excluded form the gallery, à la ign_*, noexec_*, noplot_*, NX_*, ...
This solution is more explicit than listing names at other place (conf.py) - also an option. I'm opening a PR so that we can have this on latest docs asap

[kandersolar]

Ah ha, of course! Nice work, @echedey-ls.

So renaming those files to begin with plot_, or changing our filename_pattern, would get it working again. Not sure which of those two options is best.

Edit: I am +1 to @echedey-ls's exclusion prefix idea above.