# PV-Powered Charging Station for Electric Vehicles: Power Management with Integrated V2G
###### Abstract  
The increase in the number of electric vehicles (EVs) has led to an increase in power demand from the public grid; hence, a photovoltaic based charging station for an electric vehicle (EV) can participate to solve some peak power problems. On the other hand, vehicle-to-grid technology is designed and applied to provide ancillary services to the grid during the peak periods, considering the duality of EV battery \"load-source\". In this paper, a dynamic searching peak and valley algorithm, based on energy management, is proposed for an EV charging station to mitigate the impact on the public grid, while reducing the energy cost of the public grid. The proposed searching peak and valley algorithm can determine the optimal charging/discharging start time of EV in consideration of the initial state of charge, charging modes, arrival time, departure time, and the peak periods. Simulation results demonstrate the proposed searching peak and valley algorithm's effectiveness, which can guarantee the balance of the public grid, whilst meanwhile satisfying the charging demand of EV users, and most importantly, reduce the public grid energy cost. e 20202011 August 202016 September 20202017 September 202011 August 202020  
EVs can discharge into the public grid during its \"peak\" periods and can be charged during its \"valley\" periods to achieve the purpose of peak shaving and valley filling [12]. When EVs need an energy supply, they are connected to the public grid as charging loads; when EVs are idle, i.e., EVs are seen as distributed power sources, EV battery energy can be injected into the public grid. This is the vehicle-to-grid (V2G) operation. Thus, V2G technology makes it possible for EVs to have a mobile battery function [13]. Moreover, compared with common loads, EVs have greater flexibility and dispatchability. When reasonable scheduling strategies for V2G technology are designed, and the charging/discharging behavior of EVs is planned, EV charging costs will be reduced, most importantly, the load curve of the public grid will be improved. The paper [14] proposes a time-based charging group dispatching approach to schedule the charging of numerous EVs, which enables EVs to play an important role in peak shaving and valley filling, meanwhile solving the stability problem of the microgrid system brought by the penetration of renewable energy. EV batteries and related power electronics can be used to mitigate photovoltaic (PV) sources' impact and support the public grid with appropriate control strategies. The paper [15] develops a controllable charge/discharge pattern to optimize the limitation of EV battery capacity and the impacts of PV sources. Most importantly, EVs can provide instant power, which is much faster than starting a standby power source. So, V2G technology enables EVs to act as emergency power sources in the event of a power outage [16; 17]. V2G can bring economic benefits to EV users, offset part of the EV costs, promote communication between the public grid and EVs, meanwhile, protect the environment, and solve the shortage of fossil energy. V2G services are important for reducing environmental pollution, mainly referring to the emission of greenhouse gases such as CO2 [18]. With the continuous development of renewable energy, such as PV sources, more and more renewable energy is being integrated into the power system in large quantities. Considering the intermittency and distribution of PV sources, microgrids are proposed to achieve small-scale renewable energy penetration while reducing the public grid stress [19; 20]. Surveys show that most EV users can accept the intelligent EV charging station based on a microgrid [21; 22]. The paper [23] proposes the model for an EV charging station. However, the above microgrid models and simulations do not consider V2G. Traditional V2G technology mainly refers to EVs directly connected to the public grid for energy exchange. Generally, two types of control exist in systems: centralized control and decentralized control [24].