A refrigeration trailer (reefer) truck power unit controller employs a plurality of power sources including a propulsion vehicle source driven mechanically by a diesel engine of the vehicle, and having an enhanced alternator having a pulley ratio for increasing idle speed power generation, and a passive vehicle source including a bank of solar panels disposed on the vehicle. The controller is configured for refrigerating a payload area of the vehicle utilizing power from the power sources, and employs a voltage converter for augmenting the power from the propulsion vehicle source for use with a native vehicle charging//starting system, and a transport load transformer for converting power from the power sources for powering the refrigeration system. A bank of batteries stores power from the sources for subsequent dispersal to the refrigeration unit.