Investigating encapsulation design strategy of photovoltaic cells in the case of a solar race car

Abstract

The efficiency in converting solar energy into electricity is fundamental wherever photovoltaic panels are present, still more crucial in the design of racing solar vehicles. Even minimal reductions in conversion ratio, maintained for the long solar races, cause solar cars to lose race positions and competitiveness. Here we introduce a numerical-experimental study for choosing the best combination of materials to encapsulate cells in solar roofs. The tangible expectation is to improve the performance of the monocrystalline silicon cells used in our solar vehicle by maximizing heat dissipation to the environment. The operating temperature is in fact a determining factor for efficient conversion, with efficiency drops of the order of 5% every 10 °C. Different stratifications, some of which quite unusual in solar panel design, were compared by transient thermal simulations and experiments. Specifically, five alternatives were analyzed, varying in the presence and thickness of the encapsulation materials (ETFE, EVA and PET). The main scope of the work, however, was not choosing the best among several specific hypotheses, but the development of an accurate numerical model able to predict the behavior of the solar panel in conditions close to the expected ones. This model, in fact, has provided valuable help in optimizing the vehicle design by allowing to evaluate the effect of alternative materials and construction solutions in the cell’s construction housing structure.