Solar potential on commercial trucks: Results of an irradiance measurement campaign on 6 trucks in Europe and USA

The use of photovoltaic modules on commercial trucks is considered to be a promising way to reduce fuel consumption and thus carbon dioxide emissions in the transportation sector [1, 2]. For refrigerating trucks, the energy demand (cooling energy) and availability (solar energy) are in close time correlation making the use of solar assisted cooling obvious. Several approaches and prototypes have been published since the early 90's [1-4], however, this technology has not experienced a commercial breakthrough yet. One reason for this stagnation is the uncertainty of payback time of such systems and reported technical drawbacks [5]. To overcome this reluctancy precise energy yield information is necessary to feed resilient return on investment calculations. In this work we present the result of a solar irradiance measurement campaign on 6 truck roofs operating in central Europe and north-eastern US. It is found that the best performing truck has the potential of a fuel saving of about 2113 L diesel/year and that the fuel saving potential strongly depends on the usage scenario of the truck. We find the operating conditions in the collected data to differ significantly from STC and typical PV application with 50% of the measured samples having an average daytime irradiance level below 200W/m² and 80% an average operating temperature below 25°C. In summary a cost competitive usage of photovoltaic systems on truck roofs seems possible but with tailored usage scenarios.