Hi Sam, we have a 120 watt
Solar Panel on the roof, wired tothe engine
battery. We then have a "
battery to
battery charger instead of the normal zig unit, which feeds two leasure batteries. On most days even without running the engine, we can maintain the batteries at 13 - 14 volts. We never need hook up & are completely self contained. I would recommend a
battery to
battery charger to any wild camper. It is infalible. We also have a
battery charger in circuit that works from the mains when we are at home.
Hope this helps. Judi.