# PV-Powered Charging Station with Energy Cost Optimization via V2G Services
The results show that the potential benefits from V2G are greater than the cost of battery degradation. On the other hand, research studies have investigated the optimization of V2G service in a PVCS. In [30], a dynamic searching peak-and-valley algorithm was proposed to determine the optimal charging and discharging start time of EVs based on their initial state-of-charge (SOC), arrival time, charging mode, departure time, and the tariffs in peak hours. The aim of this optimization was to reduce the burden on the public grid and lower its energy cost. A control scheme using a grid-connected inverter was developed in [31] to improve the voltage and frequency stability of a PVCS with V2G operation. This inverter can identify unusual faults of the microgrid and functions in islanding mode. The authors in [32], have modeled a PVCS to provide ancillary services where EV users can receive rewards for their V2G participation. The results proved that EVs participating in V2G service could provide high availability of service. Furthermore, in [33], an energy management strategy has been examined for the real-time control of multi-source EV charging to lower the operating cost, taking into consideration battery degradation of stationary storage and EVs for their V2G participation. In [34], a PVCS was designed with V2G service to lower the stress on the public grid and to enhance its stability during peak hours. The authors also discussed possible financial incentives that can motivate EV users to participate in the demand response. Additionally, an energy management and control system has been introduced in [35] for an EV charging station with V2G integration. This charging station featured a PV system, wind turbine, and fuel cell with grid connection. A MILP model has been proposed in [36] for a parking lot of EVs powered with a microgrid, based on PV sources, wind turbines, hydrogen energy, and a stationary storage system to minimize the total sustainability cost, as well as economic and environmental costs. The EVs can operate in V2G mode to participate in demand response, thus encouraging EV users to charge in off-peak periods instead of on-peak periods. In [37], a day-ahead operation planning method that incorporates EVs with V2G service in a microgrid was investigated to minimize the daily operation costs. A multi-objective optimization model has been proposed in [38] for a microgrid integrating EVs with V2G service. Their objectives were maximizing the use of renewable energy, maximizing the benefits for EV users, and minimizing grid load fluctuation. A heuristic optimization problem has been studied in [39] to optimize the sizing of a hybrid PV sources, battery, and diesel generator for an EV parking lot with V2G service, where EVs are considered as a flexible load. A two-stage smart charging algorithm (first stage: optimization problem, second stage: real-time control) has been proposed in [40] for buildings integrating EVs, PV sources, a storage system, and a heat pump. The optimization problem is formulated as a non-linear programming model to optimize the operation of EVs. The results show the benefits of V2G service as primary frequency regulation reserve while participants achieve energy cost reductions; however,the degradation of Li ion batteries is non-negligible. The authors in [41] have proposed an effective strategy using adjustable robust optimization to enhance the operation stability and economic cost of a microgrid by enabling V2G service during peak periods and charging for valley filling at off-peak periods to minimize the cost of operation under various constraints. The references cited earlier have highlighted the role of V2G in serving as a spinning reserve source and power regulation to lower the impact of the peak load on the grid and its associated services.