I believe this is the design of all the panels on the C-30 CB (2 sides, with one side being the ELCI). However, I believe the inverter will feed the ELCI side as long as you have the ELCI circuit switched on while inverting, although I have not tried this? I don't see this level of detail mentioned in the manual wiring diagrams so hopefully someone else on this forum can validate y/n. The water heater uses an incredible amount of electricity and still takes quite some time to heat the water from cold. The heat generated from the engine heat exchanger to the hot water tank will keep the water hot for many hours (overnight even) after cruising even for a few hours. If i'm on shore power, i will use the hot water heater heating element, but I generally don't when on the hook.