Abstract: A dual power source retrofit kit for a single power source service entrance panel. The retrofit kit is a field installable kit for retrofitting a single power source service entrance panel to a dual power source service entrance panel. The kit includes a power source selection assembly and a mounting bracket for attaching to the service entrance panel. A deadfront trim plate having a cut-out to accept the power source selection assembly is also supplied to replace the old trim plate of the service entrance panel. The power source selection assembly permits only the selected one of the primary or auxiliary power sources to provide power to the service entrance panel at any one time. The power source selection assembly is also designed such that overload protection devices/disconnect switches for both the primary power source and the auxiliary power source must be in the OFF position before switching from one power source to the other is permitted.