[hiccup]

Not familiar with the 39 Sovran electrical layout specifically, but familiar with how Tiara typically installs inverters.

It probably is powering a small subset of your AC system, like the outlets, microwave, ice maker. It is probably an inverter/charger combo and charges the house bank. You likely have a separate charger for your engine batteries. You probably need the inverter switch closed in order to charge the house batteries on shore power. It probably has AC power pass-through such that when there is AC power available from the generator or shore power, it passes that power through to the loads it's connected to. To use the inverter function, you would make sure the main DC switch is closed and operate the inverter from the small control panel you mentioned.

This is what I would expect with a factory install. Of course it is now 15+ years old, so it may have been modified along the way.