It was unusable space. The battery compartment is in there but accessible from the outside. I was able to squeeze the mppt controller, 50 amp dc charger, wire junction blocks, and a mess of wire stuffed in there. My old inverter was just outside that area under the front of oven. The old shore power supply, dead for years is in the sink compartment soon to be removed, replaced by the victron 3000 watt inverter charger. You can see the original cabinet configuration in the opening post, this reply brings you up to date on current progress. Need to make a couple wires today, get a couple fuses of various sizes, ond build the doors. Future plans include another battery, 200 watts more solar, more efficient quieter AC unit.
The original purpose of the space was to conceal vent pipes and to provide a step up to the fold down upper dinette bunk. I think this is a much, much better use of the space.