The sun is by far the largest source of clean energy and the road network is daily exposed to this big amount of radiation. At present, the solar radiation can be directly converted into electrical power thanks to the photovoltaic effect, or harvested by means of a heat-transfer fluid. This paper deals with the second solution, proposing a multilayer road system able to exploit the thermal gradient of the pavement. The system is composed of a porous core, sandwiched between two layers. The base layer is waterproof and it contributes to the mechanical performance of the entire system; the core is a porous concrete mixture for the circulation of the heat-transfer fluid and it works as a solar collector and the top layer is a semi-transparent material designed to support the traffic vehicles, guarantee the skid resistance and maximize the harvested energy. At first, the authors worked on the mix-design of the porous core and of the semi-transparent layer. Secondly, they built a working prototype in order to evaluate harvested heat energy in labcondition. In comparison to the state-of-art, the results show a clear improvement in terms of energy harvesting, leading the way for the construction of a full-scale prototype and a comprehensive evaluation in-situ conditions.