Surge power refers to the maximum power that the inverter can offer instantly. A portion of the "boot power" of the appliance is much higher than its rated operating power, such as a refrigerator, an air conditioner, or other devices with a compressor. It must meet its boot power (usually tens of milliseconds) to start normally.
AC rated power of Anker 757 PowerHouse: 1500W
AC surge power of Anker 757 PowerHouse: 2400W