Aiming at the load characteristics of electric vehicle users, this study proposes a capacity configuration method for photovoltaic-storage-changing systems based on dynamic capacity expansion and formulates system operation strategies. A comprehensive cost optimization objective function and constraint function model are established. Taking an urban charging station as an example, the load characteristics are analyzed through electric vehicle charging behavior. Leveraging the bidirectional regulation capability of energy storage, the system maintains a dynamic balance between power generation and consumption, reduces distribution network expansion costs, and conducts an economic analysis to validate the effectiveness of the proposed method. This study provides a reference for capacity configuration of urban photovoltaic-storage-changing systems.