In 2007 12 v diesel gennies did well - the boats with them also had solar and towed gennies and large battery banks so hardly ever ran their diesel gennies. The AC gennies ran on average for 4.9 hours each day - what a pointless excercise just to charge 12v batterries. Go for the DC option and an inverter for all your AC power. When you need it a DC genny will charge at 250 amps. Search the archives for more on this.