How long can a 12 Volt Battery Power a 700 Watt Appliance? With a 15 Watt Solar Panel?

I am trying to prepare a solar panel setup for Burning Man. For my tent I was hoping to power a 700 Watt George Foreman Grill for about 2 hours per day. I was planning on getting a 15 Watt Solar Panel with a 7amp charge controller. How long can a 12 Volt Battery Power a 700 Watt Appliance? Would a 15 Watt Solar Panel be enough to charge this back up on an 8 hour day basis? How could alter this setup to achieve the correct wattage and charge time? Any help would be GREATLY appreciated!