Implementation of a solar aided refrigration unit for refrigerated trucks employing photovoltaic generators

Solar aided refrigeration system can represent a simple and feasible solution for improving the sustainability of refrigerated transport. The paper presents the design and the performance of an electric powered refrigeration unit integrated with photovoltaic generators installed on top of the refrigerated box of a light truck. The system prototype has been tested in stationary conditions, demonstrating the capacity of the solar system to impact significantly in the net energy balance of the refrigeration unit. The system performance during an urban multi-drop delivery scenario and hot climatic condition are then assessed using a dynamic lumped model simulation. Simulations are also used to discuss the sensitivity to the battery pack capacity size and the shading conditions caused by the urban canyon effects are investigated. Results demonstrate that, on a yearly base at Athens climatic conditions, the solar panels can provide from 65% to 112% of the energy consumed by the cooling unit, depending on the time spent by the truck under direct sunlight. Larger batteries are justified only when long periods of direct light are expected.