Thermal and electrical performance of a novel photovoltaic-thermal road

Abstract

The solar road is a new type of technology for solar energy conversion. As the solar energy utilization efficiency of a solar road is too low, to solve this issue, a novel photovoltaic-thermal road is proposed in this paper. In addition, a mathematical model is developed to evaluate thermal and electrical performance of the photovoltaic-thermal road, and it is validated by experimental data. Moreover, the performance of a simple water system of the photovoltaic-thermal road is investigated and compared with that of a photovoltaic road. The results show that overall energy efficiency of the photovoltaic-thermal road system is 3.95 times that of the photovoltaic road system. In addition, this study analyzed the effects of some meteorological and geometric parameters on the system performance. The pipe diameter was found to have little effect on the overall performance of photovoltaic-thermal road. Furthermore, the solar-radiation intensity, packing factor of photovoltaic cell, mass flow rate of circulating water, and transparent surface transmissivity have positive influences on the overall energy efficiency; in contrast, the wind speed and burial depth of the pipe have negative influences, implying that a windless environment is conducive to the energy output of the PVTR system. An optimum thermal conductivity of asphalt concrete can maximize the overall energy efficiency; for this study, the recommended range of this value is from 1.0 to 1.5 W/(m·K). The results of this study substantially contribute to the state of knowledge regarding photovoltaic-thermal road designs.