A mobile power supply unit includes a base and a housing including at least one housing member secured to the base and movable relative to the base. The mobile power supply unit further includes a generator disposed within the housing, and a battery disposed within the housing. The mobile power supply unit further includes an inverter electrically connected to the generator and the battery, and an electronics enclosure including an electrical port, and a transfer switch electrically connected to the inverter and adapted to provide power through the electrical port. The mobile power supply unit further includes a portable transfer switch having a first electrical cable selectively electrically connectable to the electrical port and a second electrical cable selectively electrically connectable with a power receptacle of a building.