Hunter 30t Panel - what is this supposed "solar" area to be?

Apr 21, 2020
Hunter 30T Marina Del Rey
Hi all,
Question about this 1991 Hunter 30T battery switch/shore power panel. There are two empty holes for "solar panel", but I have no idea what they're supposed to be for. Does anyone have an idea, or better yet, a photo of what is supposed to be in these holes or what it's supposed to connect to? I'm in the process of setting up solar panels/mppt controller, and wondering if this area comes into play at all. Check out this photo: