Photovoltaic and Battery System Sizing Optimization for Electric Car-Sharing: An Energy and Economic Assessment

The growing adoption of electric vehicle (EV) car-sharing, while contributing to reduced traffic congestion and urban pollution, still presents concerns related to energy supply. Since most grid electricity is still fossil-based, global environmental benefits remain limited. Integrating photovoltaic (PV) and battery energy storage systems (BESS) into EV charging hubs (CH) offers a promising solution. However, optimal system sizing is critical to balance energy benefits and cost-effectiveness. This study proposes a multiobjective optimization method to determine the optimal size of PV-BESS systems integrated with an EV CH, maximizing energy self-sufficiency while minimizing annual total cost. To enhance battery lifetime estimation, a semiempirical battery degradation model is developed. The method is evaluated using the power demand profile of a real-world CH in Bologna. A multicountry analysis across six European nations, which includes Spain, Denmark, Italy, Germany, France, and The Netherlands, assesses how varying solar radiation and electricity costs affect system performance. Results show that self-sufficiency ranges from 51% in Denmark to 72% in Italy and Spain. The optimally sized PV-BESS configuration is economically advantageous for all countries except Denmark, and, in general, pursuing higher self-sufficiency levels leads to exponentially increasing costs, revealing diminishing economic returns.