Photovoltaic pavements in urban areas: more benefits or drawbacks?

Many carbon dioxide (CO2) emissions are caused by electricity generation with fossil fuels and can raise global temperatures, generating human health and environmental problems. Several studies have identified and confirmed the potential benefits of road photovoltaic (PV) pavements as a source of energy. This study analyses the advantages of such pavements installed on two 400 m-long and 3 m-wide sidewalks in Ciampino (Rome). The innovative use of PV pavements has been evaluated in terms of environmental, thermal, and economic impacts. The environmental impact has been quantified in kgCO2-eq./kWh emissions through SimaPro 9.39.3 software. The electricity produced through solar energy reduces the CO2 emissions of 89.9-ton CO2-eq./year compared to the Italian energy mix. The microclimatic analyses from ENVI-met software compared Surface Temperature (ST), Air Temperature (AT), Mean Radiant Temperature (MRT), and Predicted Mean Vote (PMV) between the actual asphalt pavement and the photovoltaic one. The results show the ineffectiveness of PV to counteract Urban Heat Islands; during a summer day, the maximum differences are ΔST = 4.43 °C, ΔAT = 0.12 °C, ΔMRT = 0.20 °C, and ΔPMV = 0.03. Finally, the economic analysis demonstrated the current Italian prices do not ensure a breakeven point for this investment after a 25-year service life.