Design of a Novel Photovoltaic Storage–Charging System

As the power ratings of electric vehicle (EV) charging piles continue to increase, direct grid-powered charging imposes significant load impacts on the power grid. Issues including line overload, voltage fluctuation, and frequency deviation induced by abrupt load surges become particularly prominent during peak load periods. Accordingly, energy storage batteries are required as buffer units for high-power charging piles. Energy storage batteries absorb photovoltaic (PV) generation and off-peak grid electricity, and supply power for EV charging during peak load periods. This configuration not only mitigates grid load impacts but also generates economic benefits by leveraging the tariff difference between peak and off-peak load periods. To fully accommodate PV generation and maximize economic returns, the capacity of energy storage batteries should be optimally sized based on seasonal daily PV output and EV charging demand. Furthermore, charge–discharge scheduling strategies are formulated in accordance with time-of-use (TOU) tariffs, as well as the power balance between PV generation and EV charging load. This paper proposes a novel PV storage–charging system. By reconfiguring contactor contact combinations, the system implements optimized charge–discharge control to alleviate grid load disturbances and maximize economic benefits, while reducing the number of power converters. Compared with mainstream commercial counterparts, the proposed system cuts manufacturing costs by more than 31.25% and improves EV charging efficiency by more than 1.23%.