Describe the bug
LGTM shows 6 errors, at least one seems easy to fix there is a self alignment that seems redundant

To Reproduce
https://lgtm.com/projects/g/pvlib/pvlib-python/alerts/?mode=list&severity=error

Expected behavior
No errors?

Screenshots
https://lgtm.com/projects/g/pvlib/pvlib-python/alerts/?mode=list&severity=error

Versions:

• pvlib.__version__: 0.9ish
• pandas.__version__: ?
• python: 3

Additional context
https://lgtm.com/projects/g/pvlib/pvlib-python/alerts/?mode=list&severity=error