Will get better photos next time I'm down there now that I know what I'm looking for.
No that's it. The panel is in the garage, and the other side of that panel on the outside of the house is the meter. Home was built in 1966.
So I think that is a pretty nice panel for 1966. But yeah, it is a max of 100a. More likely 60a but we will see with better pictures.
If it can be done safely, I would be curious to see pictures of the inside of the panel too just to see wire gauges, panel configuration, etc...
It might be helpful to see the meter base outside as well as well as the feed wires (overhead I assume?).
On the plus side, if replacing this panel is necessary, it would be super trivial to do. Like maybe a couple hundred bucks in parts. Residential panels are very inexpensive. The wiring all looks long enough and is in decent enough shape that dropping in a physically larger panel in the same place would be easy. The lack of sheetrock makes it just that much easier. I am not a professional, but I could probably do it in an afternoon. Turn off main breaker, pull meter base outside, remove all wires from panel then remove panel, install new panel and re-install all wires into new breakers. Re-install meter base, turn back on power. Call for inspection and call power company to re-tag meter (you should have called them ahead of time to let them know you need to cut their tag).
Depending on the meter base setup and feed wires, it might be extremely easy to upgrade to a 100a or 200a electrical service at the same time. The utility will probably upsize their wires all the way to the meter base for free for an existing customer. You just may have to upgrade the meter base and any conduit and the wire in to your new panel.
I am guessing we are going to find that your parents panel is very close to its limits with a 2400 sq foot house on either a 60a or 100a service. (since it has AC too!)
I am guessing the house is gas for just about everything? There are only two 240v breakers. One for AC. I am guessing the other (30a) is a dryer? Or is it a water heater?
I did just notice one tandem breaker in there that I missed before. If the panel is rated for tandems in more positions then you very well might be able to add a 240v circuit to that existing panel, but load calculations are going to be very tight if not make it impossible.
P.S. If the 30a is a dryer you could potentially just charge off that plug when there (assuming your parents don't need to do laundry while you are there).