If you need to generate 110V ac power from a battery, you need an inverter. Since the battery will only power the inverter for a finite amount of time, you'll need some way to recharge the battery. An inverter/charger, such as some of the Xantrex models can perform both of these functions.
The battery will need to be a deep cycle one with sufficient capacity. Often, this means more than one battery. You'll also need adequately sized wires and space to mount/store all this stuff.
Where are you planning to use the system and how long will you need to be consuming 1500 watts?
Tell us more about your intended use and we might have a better solution for you.