Need a small breaker panel to finish Inverter Replacement

I see you only have 120 volts to the breaker. Most panels you'll find in stores are set up 240 volts.

If you want a 30 amp main and can't find a panel, just use a "Main Lug" panel (they're smaller) and don't feed the lugs. Feed the panel using a 30 amp breaker using one of the panels breaker slots and mark it as "main". Jump the lugs together so both bars have 120 volts.