Abstract: Disclosed are various embodiments for a self-contained power supply. A container is configured to be placed separate from a powered structure, such as a house or place of business. The container houses a power supply unit that includes a battery bank and an inverter. The battery bank receives multiple charging currents from multiple power sources, such as a grid power source and an auxiliary power source. The inverter uses electrical energy stored by the battery bank to provide an output current to the powered structure.