I look like a hole.. probably why they had a panel covering it in the first place.
Looks to be a power distribution board and possibly your transfer switch over on the right. Your converter and main power center is more than likely just above there further up.
No. If your unit is like mine, the converter is an Intellipower box mounted on the floor under the sink. It's visible by pulling the drawer all the way out and accessible by removing the drawer.