Abstract: The present invention relates to a refrigerated trailer for storage and transport of refrigerated products such as perishable food. The refrigerated trailer comprises an insulated box with a side door; a refrigeration unit for cooling air inside the insulated box, the refrigeration unit including an engine for supplying mechanical power to the refrigeration unit, batteries, and a compressor operatively coupled to the engine; an inverter electrically coupled to the batteries for supplying AC power; and an air curtain unit located above the side door, the air curtain unit including fans operating on AC power from the inverter, wherein the fans blow internal air downwardly over the door opening to limit air exchange between the insulated box and the outdoors.