When a public utility sells electric power to other than its retail customers or disposes of, sells or retires from service any facility, the commission may evaluate the efficiency or prudence of such electric power sale or disposition, sale or retirement from service, and if it finds that any such action was inefficient or imprudent, or caused a reduction of electric power available to its retail customers or in electrical generating capacity, the commission may reduce the revenue requirement resulting therefrom.
K.S.A. 66-128j