This set would last almost two hours on a set of eight AA 1.2V NiMH batteries with 1800mAH capacity each (like the kind Radio Shack sells)
. Remember that each bulb uses half a watt-hour per hour. So 12 bulbs use 6wH per hour. Our batteries store (8 batteries x 1.2V x 1800mAh = ) 17,280mWh, or 17 wH. Therefore our 17 wH VGN-FZ180E battery pack will power this 6-watt strand for almost three hours.
So there you have it, three ways to get Christmas lights to run off batteries!