Implement hoverxref for floating tooltips

docs/sphinx/source/conf.py

@@ -56,11 +56,30 @@
     'sphinx_gallery.gen_gallery',
     'sphinx_toggleprompt',
     'sphinx_favicon',
+    'hoverxref.extension',
+    'sphinx.ext.intersphinx',
 ]
 
 mathjax3_config = {'chtml': {'displayAlign': 'left',
                              'displayIndent': '2em'}}
 
+# used with hoverxref to link to other projects' documentation not hosted by
+# readthedocs
+intersphinx_mapping = {
+    "python": ("https://docs.python.org/3/", None),
+    "sphinx": ("https://www.sphinx-doc.org/en/master/", None),
+    "numpy": ("https://numpy.org/doc/stable", None),
+    "scipy": ("https://docs.scipy.org/doc/scipy", None),
+    "matplotlib": ("https://matplotlib.org/stable/", None),
+}
+
+# Enable hover tooltips
+hoverxref_auto_ref = True
+hoverxref_roles = ["class", "meth", "func", "ref", "term"]
+hoverxref_role_types = dict.fromkeys(hoverxref_roles, "tooltip")
+hoverxref_domains = ["py"]
+hoverxref_intersphinx = list(intersphinx_mapping.keys())
+
 napoleon_use_rtype = False  # group rtype on same line together with return
 
 # Add any paths that contain templates here, relative to this directory.

pvlib/irradiance.py

@@ -244,7 +244,7 @@ def beam_component(surface_tilt, surface_azimuth, solar_zenith, solar_azimuth,
     solar_azimuth : numeric
         Solar azimuth angle.
     dni : numeric
-        Direct Normal Irradiance
+        Direct normal irradiance, see :term:`dni`. [Wm⁻²]
 
     Returns
     -------

pyproject.toml

@@ -66,6 +66,7 @@ doc = [
     'sphinx-toggleprompt == 0.5.2',
     'sphinx-favicon',
     'solarfactors',
+    'sphinx-hoverxref',
 ]
 test = [
     'pytest',