The transition to Electric Vehicles is a pivotal moment in the automotive industry and environmental sustainability. EVs offer numerous advantages, including a notable reduction in greenhouse gas emissions, increased energy efficiency, and the conservation of finite fossil fuel resources. Moreover, these vehicles drive technological advancements that benefit various industries. However, the success of this transition heavily relies on the development of a robust EV charging infrastructure and technologies such as power switches.

EV chargers are the backbone of the EV ecosystem, facilitating the widespread adoption of electric vehicles. They play a vital role in addressing concerns such as anxiety due to range by providing convenient and accessible charging points. A well-established charging infrastructure accelerates the adoption of EVs, reeling in further investments in green technology. Combining EV chargers with renewable energy sources enhances their environmental benefits, making electric vehicles a truly sustainable transportation option. To ensure a cleaner and greener future, continued investments in both electric vehicles and their supporting infrastructure are paramount.

One such example of a hybrid electric power infrastructure is a solar PV power network where the main source of energy is the sun, and this facilitates the consumers to be producers by transmitting solar energy produced at individual levels to the main grid. However, this method is made practical only by integrating an Energy Storage System to reduce harmonics and irregularities created by different solar irradiance. Figure 1 shows a typical grid architecture of a solar EV charging station, where it is preferred to have minimal power conversion stages in order to increase efficiency.

Figure 1 Solar EV Charging Station Integrated with the Grid

Ⅰ. Innovative Storage Solutions to Meet the Growing Demands of Solar PV Systems

The ever-increasing cost of electricity, frequent power interruptions during peak periods, and blackouts have led consumers to explore alternative energy sources in order to achieve independence from the grid or reduce their reliance on it. In order to overcome this issue, Mouli et devised a bidirectional, three-port, 10 kW PV system that acts as a converter for charging of EV directly from PV. This system proved to be a better choice of energy source as it had less maintenance, lower installation cost, no moving parts and a longer working life. Moreover, the EV charging framework can be integrated with the commercial grid in order to revert any excess energy produced back to the grid and lower the overall cost. However, an optimal energy storage solution with appropriate sizing is a must for PV systems for the application of charging EVs.

Electric cars depend on specialized energy storage systems to enable fast charging, crucial for long journeys. These ES batteries are designed to store a lot of energy and release it quickly, ensuring rapid charging. Beyond speed, they also enhance the stability and reliability of the charging process by smoothing out power fluctuations. In essence, ES batteries are the key ingredient that makes swift and dependable EV charging a reality. Moreover,  an Energy Storage System is of utmost importance to a power grid as it facilitates the seamless provision of power and also acts as a storage system in case of a power loss. The selection of an ESS is critical as it decides the cost, complexity, reliability and efficiency of the power grid, moreover, different ESS such as hydrogen storage systems, supercapacitors, flywheels and batteries have their own advantages and disadvantages.

The decreasing cost of batteries, driven by advancements in technology and the ongoing efforts to reduce toxic elements while enhancing safety and durability, has positioned energy storage systems as an ideal choice for a variety of applications. However, it's worth noting that as temperatures soar to extreme levels, the efficiency of batteries tends to decrease, highlighting the importance of temperature control and management in optimizing their performance. Among various ESS solutions, Li-ion batteries emerged as the strongest contender as it has high efficiency, compact size, less self-discharging time, high power density and rapid response time. On the other hand, lithium sulphur battery proved to be a better alternative than Li-ion as it provided more reliability, and a high-speed response, however, it is still in development and needs more research.

Ⅱ. Exploring Grid-Connected Architectures for Superior Reliability and Efficiency

In recent years, solar PV systems have been one of the most popular sources of energy in the industry, however, it is essential to merge this technology with the existing grid. Grid-connected architecture represents a sophisticated approach to integrating solar PV into the existing electrical grid. Grid-connected architecture has a profound impact on a solar photovoltaic (PV) system, as it fundamentally changes how the system operates and interacts with the broader electrical grid. In essence, there are several grid architectures based on the type of bridge between the PV source and the ESS. Figure 2 shows the basic inline system where the PV source and the ESS are linked with a DC/DC converter and inverter, due to which bidirectional flow of power is possible with a suitable communication setup.

Figure 2 Block diagram Representing Inline Systems.

On the other hand, the DC/AC coupled system utilizes two DC-DC converters as a bridge between the PV source and the ESS as shown in Figure 3. Since all three converters are fused together, an intricate control algorithm is vital to maintain a constant voltage. However, this grid architecture provides the best efficiency and flexibility since the conversion is fed through different converters.

Figure 3 Block Diagram of a  DC-AC coupled system

Ⅲ. Conclusion

The advancements in storage technologies and grid architecture are pivotal in shaping the future of electric vehicle charging systems. These innovations not only make EV charging more efficient and reliable but also contribute to grid stability and sustainability. As electric vehicles become more mainstream, the collaboration between clean energy storage and smart grid solutions will be instrumental in ensuring a seamless and eco-friendly charging experience for all. Moreover, different grid architectures like DC coupled system, AC-coupled system and inline systems have their own sets of advantages and disadvantages.

On the other hand, smart storage solutions are a must due to the fluctuating supply of energy and grid overloading. These energy storage systems increase efficiency by storing excess energy during peak hours and releasing it when the demand is high. This not only relieves pressure on the grid but also reduces electricity costs for charging station operators. Moreover, it enables fast-charging stations to deliver a consistent and high-powered charging experience without overwhelming the local grid.