A 250L tank with a 3.6kW electric heater element, programmed to turn on when batteries hit 98% full (and off again when batteries fall below 95%). We really on

A 250L tank with a 3.6kW electric heater element, programmed to turn on when batteries hit 98% full (and off again when batteries fall below 95%). We really only use it for short showers, and it stays warm enough for that, for about 3 days without power.