EV Charging Stations

1 Electromobility

1.1 Introduction

It has become evident that the green transition of the transport sector is necessary. The sector is responsible for 24% of direct CO2 emissions from fuel combustion. However, despite efficiency improvements, electrification and greater use of biofuels, global transport emissions have increased by 0.6% in 2018 and 1.6% annually in the past decade [1].

The story of EVs started long ago before internal combustion engine vehicles were introduced. However, following a number of vicissitudes, EVs previously only made up a small percentage of the vehicle market. Modern EV technologies are relatively new, and EVs are becoming increasingly popular because of their many benefits, including zero emissions, independence from fossil fuels, efficiency, relative quietness, and so on.

An increase in electric vehicle (EV) shares would directly impact passenger vehicle emissions and, thus, global emissions from transport. Therefore it is encouraging that the adoption of EVs is rapidly growing. However, this also substantiates the need for better planning, especially for the charging infrastructure, to improve and support the transition to e-mobility. This growth in e-mobility motivates research concerning the overall user experience to facilitate both ownership and usage of EVs.

Growing EV market results in a large number of EV charging stations, which are the medium for EV grid integration. The implemented charging stations can be classified into residential and non-residential types and can facilitate slow charging (level 1 and level 2) as well as fast charging (level 3 and DC). A significant portion of EV charging is residential charging with slow charging ports; however, future charging stations are planned to be built at commercial places to facilitate them as EV refuelling stations with all types of charging ports. Several commercial charging stations have already been established, which have fast charging points and can charge an EV within an hour.

Traditional transportation system contributes significantly towards rising unsustainable pollution levels. To address this problem,  governments across the globe are making policies to introduce electric vehicles (EVs), which will play a crucial role in future. Consequently, high penetration of EVs is expected in the imminent future. Therefore,  the impact of  EVs on the optimal operation of electromobility solutions should be discussed.

1.2 Factors Affecting EV Charging

As the number of electric vehicles on the road continues to grow, so does the need for reliable and safe charging methods. While most electric cars come with a standard charger that can be plugged into any standard outlet, there are other ways to charge your electric vehicle that may be faster or more convenient. This article will explore all the different ways you can charge your electric vehicle, from standard chargers to public charging stations to home charging stations. We will also provide a comprehensive guide on charging your electric vehicle safely and efficiently.

End-user considerations concerning charging solutions include many aspects of EV infrastructure [2]. Notably, the price of charging is far more complex than the price of refuelling a conventional car as the price can differ highly depending on location (e.g. home or public) and charging speed (e.g. fast charger or not). In addition, dynamic pricing is widely considered to reduce peak load on the electrical grid.

Similarly to the telephone provider market, charging providers have introduced products where users pay a fixed monthly fee to obtain lower (per kWh) charging prices. Some studies have suggested theoretical frameworks for such business models and revealed preference data had been used to study charging demand, e.g. for location and charging type and fast charging. However, the complexity of EV charging calls for more analyses of charging attributes, both when it comes to long-term decisions (e.g. contracts) and short-term decisions (e.g. where to charge).

As the market in most countries is still not sufficiently developed for studies based on revealed preference data, some studies have used stated preference experiments to study some of these aspects. Others analyse the effect of idle time fees to improve access to chargers, the choice between charger types for inner-city charging, dwell time and charging speed, or overnight smart charging.

2 Electric Vehicle Charging Infrastructure

The overall EV charging infrastructure entails power infrastructure, communication, and control infrastructure, as shown in Fig. 1.

2.1 Power Infrastructure

The power infrastructure provides a system or an electric circuit for power flow between EVs and the grid. It can be categorised according to the physical contact requirements, power flow direction, types of power used, and accommodation of the charging circuit.

EV charging operates either AC or DC power supplies. The former have different voltage and frequency levels following the power system of the concerned country. In terms of voltage levels, AC charging can be ranked into Levels 1, 2 and 3, where level 3 has the highest voltage. Levels 1 and 2 charging facilities can be deployed in a private property, while intalling Level 3 charging facilities, involving transformer and separate wiring, must obtain permission from utilities and are usually built in public charging stations. DC charging is faster at the same voltage level and usually has a high charging power capacity. The latest DC fast charging technology can completely charge an EV within as low as twenty minutes [3].

The charging circuit can be placed either in a car (on-board charging) or a charging station (off-board charging). Apart from that, wireless charging can be deemed as a third type of system, in which the energising coils are set up outside the vehicle; still, the converter and receiving coil are mounted inside the vehicle. This method is suited for power transfer between the EVs and charging stations.

The charging topologies can be classified into conductive and contactless from the physical contact perspective. A conductive charging system preserves physical contact between the battery on-board and the power supply, whereas a contactless alternative transfers power without any physical connection. Conductive technology can be subdivided into ordinary charging (Levels 1 and 2) and fast charging (Level 3). The newest charging stations use fast charging to charge vehicles, and it is the key to increasing the popularity of EVs.

A contactless charging system generally uses WPT technology to charge the battery. WPT system can operate in every voltage level (Levels 1, 2 and 3) and has a power rating of up to 20 KW. The recorded efficiency is up to 90% [4]. WPT can be divided into four types based on the charging technology: inductive, capacitive, resonant inductive, and low-frequency permanent magnet coupling power transfer.

EV chargers can be divided into unidirectional and bidirectional based on the direction of power flow. A charger with a topology defined as unidirectional uses a unidirectional DC-DC converter and a diode rectifier for charging control. The unidirectional device is easy to control because of less complexity. It has fewer interconnection issues and minimises battery degradation compared to bidirectional models.

A bidirectional EV charger has a grid-connected AC-DC converter and a bidirectional DC-DC converter. This charger can operate in either charging or discharging mode, enabling EVs to deliver various ancillary services to the grid. Yet, the EV battery lifetime can be spoiled by the regular cycling of the discharging power back to the grid.

2.2 Control and Communication

The key component for real-time monitoring and control of EV charging is a control and communication system. Although EV charging implicates an additional load in the power system, it can be scheduled to cut down the peak demand [5] and the charging expenditures. As elaborated below, proper management and coordination of stations connected with the grid based on the communication infrastructure and control architecture applied in the EV station can help in this sense.

In static charging, the car is considered to be parked in a charging station while charging. On the contrary, dynamic or mobility-aware charging scheme integrates different temporal movement, such as EV arrival and departure time, trip history and any unplanned occurence of EV arrival/departure.

Regarding charging coordination, uncoordinated approach means that EV batteries either trigger charging immediately when plugged in or begin after a user-adjustable set delay and hold the charging until they are fully charged or disconnected. On the other hand, coordinated or intelligent charging optimises the time and power demand and decreases daily electricity costs, line currents, voltage deviations, and transformer load surges. A simple coordinated charging technique is off-peak charging, where the EVs are charged at a specific daytime point when the grid load is minimum.

Available communication protocols can be interpreted into wired and wireless communication technologies. These technologies are used for grid integration in different private networks, such as the home area network (HAN), building area network (BAN), industrial area network (IAN), neighbourhood area network (NAN) and field area network (FAN). As discussed below, these networks are used to rule and monitor the charging/discharging and other domestic uses of electricity.

The wireline technologies are suitable for long-distance data transfer, such as the charging stations for EVs distributed in big metropolis. Within wireline communication technology, the most widespread protocol is data communication over a power line (PLC) which operates the same power line to send and receive signals. The advantages of this protocol are its reliability and robustness to interference. Several protocols that use the PLC concept are UPA, HomePlug 1.0, HomePlug AV, HD-PLC, and HomePlug turbo [6]. Optical and Digital subscriber line (DSL) protocols can also be found in the wireline communication system

The data rates for the optical communication protocol are significantly higher (up to several Gbps), and the range of transmission is also quite higher (several kilometres) than the PLC. Also, it is resilient against electromagnetic interference. Thus, data transfer over a high-voltage line is suitable using this technology. DSL protocol incorporates digital communication over telephone lines, therefore, does not require a separate infrastructure setup.

Wireless communication is also required for a complete communication structure, such as data exchange between vehicles and charging stations. It is the prime medium to provide charging status information to electric vehicle users. The wireless communication network is built using Wireless LAN devices in a hierarchical mesh structure to interconnect electrical devices. The popular wireless communication technologies for EV grid connection include Zigbee, cellular, wifi, WiMAX and satellite networks.

3 Pros and Cons of EV Charging Stations

3.1 Public vs Private Stations

As the number of electric vehicles (EVs) on the road continues to grow, so too does the demand for EV charging stations. However, there is still some debate as to whether or not these charging stations are actually beneficial. In this piece, we’ll take a look at the pros and cons of EV charging stations so you can make an informed decision about whether or not they’re suitable for you.

In the United States, there are 41,000 electric charging stations. President Biden’s American Jobs Plan asks for the construction of 500,000 more. The US’s 1.4 million drivers of electric vehicles must “fill up” just like those of gasoline-powered cars.

The main benefit of EV charging stations is that they provide a convenient way for EV owners to recharge their batteries. In many cases, these stations are faster and more reliable than home charging options. They also tend to be located strategically, such as near shopping centres or highways, making them more convenient for drivers.

However, there are also some drawbacks to EV charging stations. One of the biggest concerns is cost. These stations can be Costs for EV charging stations that go beyond merely setting up a pump. A company must think about networking its station to optimise value, save costs, and be eligible for several utility incentives. Additionally, a “smart station” produces operational data to aid in managing energy consumption and ultimately saving money.

The fact that public EV charging stations don’t have hefty upfront expenses is one of its main advantages. You only need to pay for the electricity and station usage fees because a business will already have paid for and installed the station. Another advantage of public EV charging stations may be that they occasionally have pricey rapid charging terminals that are out of reach for most homes [7]. As a result, some public charging stations are preferable for situations where you need to charge your car rapidly but are in a hurry.

While there are many advantages to using public EV charging stations, there are also possible disadvantages if an EV owner intends to use them exclusively. Cons of using only public EV chargers when you don’t have an at-home charger include some of the following:

• Long lines for using a public charger at charging stations: You might have to wait in line when you arrive at a charging station. You will have to wait a bit longer as your car charges after a slot becomes available. Using an at-home charger as your primary source of charging is frequently preferable, saving public chargers for longer excursions or times when you’re not in a rush due to the risk of extended wait times.
• Inconvenient searching for public stations: If you are unfamiliar with the locations of public charging stations in your neighbourhood, it may be difficult and stressful to discover one. It can be helpful to have a home charger you can use before taking your EV to an unknown place, even after you locate all the public stations along your usual route.
• Potential damage to your battery: Using Level 3 fast-charging stations frequently will cause your EV’s battery to deteriorate more quickly than using Level 1 or Level 2 chargers for the bulk of your charges, even if public charging stations are typically safe for your battery.

Given the possible disadvantages of relying only on public charging stations for your EV charging requirements, you’ll probably be interested in learning more about the benefits of at-home EV charging stations [8]. Below are some of the major advantages of at-home EV chargers:

• More comfort: Having a charging station at home eliminates the need to travel to a public station each time you need a charge. You can charge your car while lounging on your couch or dozing in your bed rather than having to wait in a parking lot.
• Increased savings: It is incredibly cheap to charge your car at home. The US Department of Energy determined that charging EVs at home only costs about $0.04 for every mile of charge for EVs that use 33 kWh over 100 miles and for households with power costs of 0.13 per kWh. Electricity costs at many public charging stations are higher, so charging at home can save you money. Thanks to these savings, a domestic EV charging station might eventually pay for itself.
• Greater home value: A higher home value EV charging stations not only provide savings but also convenience and added value to your home. A home with an integrated EV charger is a desirable feature as more current and future homeowners transition to electric vehicles.

3.2 The Cost of an EV Charging Station

According to Future Energy [9] research, the average cost of installing an EV charging station for a level two station is about $6,000 per port. Infrastructure, apparatus, soft expenses, subsidies, and software, however, all have an impact on the price of commercial EV charging stations.

Factor 1: Infrastructure

Through its connection to the utility company, a charging station provides electricity to automobiles. However, these electrical conduits might need to be upgraded, running between $12,000 and $15,000 in the US on average.

Costs associated with electric car charging stations are mostly influenced by infrastructure. For instance, it might only take a few hours for an electrician to work on connecting to an existing 240-volt circuit. However, the expense to establish a dedicated 480-volt circuit might be in the tens of thousands. Why are they different? Electrical panels, meters to track electricity use, or even an additional transformer are costs that come along with an electrical update. For power lines, an upgrade can also need boring, trenching, and cement work.

Factor 2: Equipment

Equipment charges, in contrast to infrastructure costs, are largely constant and based on the degree of charging. Residential level one chargers have an average price of $600 for a dedicated 120-volt circuit. Level-two or level-three chargers are required for commercial organisations to manage the load; a home charger is insufficient.

The level three, or direct current fast charge, specification is the highest for a commercial EV charging station (DCFC). A vehicle can be charged at level three stations using 480-volt direct current in an hour. For a single port, level three stations cost about $40,000.

Most commercial establishments look to install level two charging stations because they offer a balance between power and affordability and operate on 240-volt power. A level two electric vehicle charging station can charge two automobiles at once in eight to ten hours and costs about $2,500 for a non-public-facing station and $5,500 for a public-facing dual-port station.

Factor 3: Soft Costs

Working with an experienced partner to create unique settings and package the cost of extra commercial EV charging station components can help businesses generate value. For instance, a customer can select personalised parking space striping and signs to match the charging environment, costing roughly $1,000-$2000 but improving a business’s branding.

Additionally, a company could need protection bollards, which cost some hundred dollars each and are short, strong poles that shield the equipment. Or a station might need parking blocks, which cost more than $500 each.

Factor 4: Software

The owner of an EV charging station must install software that networks with the utility provider to be eligible for some financial incentives. In order to enhance the system as a whole and understand the demand for EV charging, the utility company gathers and analyses data from networked charging stations. Typically, it costs under $40 per month for each port to host this data on the cloud.

Beyond qualifying for incentives, companies that use data wisely can save money in the long term. How? By monitoring peak load, the highest amount of electricity used in a set period, businesses can monitor the rate of their electric bills. Innovative solutions stress proactive management of electricity usage through cutting-edge software platforms. These integrate EV charging stations with existing operational data, interacting with the utility company and managing peak load demand.

3.3 EV Adoption and Charging Infrastructure

Several studies provide quantitative estimates of the preference for charging speed in connection with vehicle purchase. However, most studies do not separate destination (slow) and fast charging choices. Only a few reports have reported separate effects for fast charging speed, but their quantitative values differ highly.

Mixed effects have been found when it comes to public charging infrastructure on EV adoption. In a study that includes 4885 participants across Denmark, Finland, Iceland, Norway, and Sweden, the effect of public charging station availability on EV adoption is not significant [10] when other factors are taken into account. Still, 89% of the respondents believe this attribute is necessary.

However, a study in Sweden found that the local policy instrument of public charging infrastructure has a significant and positive impact on the EV adoption rate. It also affects EV adoption to a higher degree in urban municipalities than in suburban and rural municipalities [11]. The availability of charging infrastructure is positively correlated with EV adoption. In contrast, both the distance from home to public charging for individuals without access to private charging as well as availability affect EV demand positively.

However, determining the exact influence on EV adoption requires further experience with later market stages. While the high availability of charging infrastructure does not automatically lead to high adoption rates, low availability is an inhibitor to EV adoption. Similarly, in relation to fast charging, even though long-distance trips often represent a small share of annual driving needs, this factor is important for EV uptake; as such occasional long-distance trips are essential for users.

We could refer to the relationship between charging infrastructure and EV adoption as a ”chicken-and-egg” conundrum where better-charging infrastructure acts as a safety net, reduces range anxiety among users, and promotes EV usage. However, on the other hand, the installed chargers are only financially viable if more users ensure payments for charging services.

Based on the above discussion, what can be said with some certainty is that charging infrastructure is an important factor in increasing EV market shares. However, there is much uncertainty concerning the size of this effect and how charging can support future EV uptake.

3.4 Safety Standards

Safety measures are a mandatory part of EV charging and grid integration. The safety standards for EV charging and grid integration are defined by the International Organization for Standardization (ISO), y The Institute of Electrical and Electronics Engineers (IEEE), Underwriters’ Laboratories (UL), the International Electro-technical Commission (IEC, Britain), the Society of Automotive Engineers (SAE, United States), and the Japan Electric Vehicle Association (JEVA, Japan) & CHAdeMo Association. However, organisations like The National Fire Protection Association (NFPA) and National Electric Code (NEC) work on safety measures mainly. The standards and codes established by these organisations are elaborated below.

IEEE1547 is known as “Standards for interconnecting distributed resources with electric power systems.” It is applicable for all DER technologies with a collective capacity of 10MVA or less at the PCC, covers requirements relevant to the performance, operation, testing, safety considerations and maintenance for interconnection of DERs, and emphasises the installation of DERs on primary and secondary network distribution systems.

NFPA is a worldwide leader in providing fire, electrical and life safety to the public. The standard released by NFPA in the area of EV and its grid integration is NFPA 70 [12], which covers instructions on electrical equipment wiring and safety on the customer side of the PCC. They include:

• Electric conductors and equipment installed within or on public and private buildings and other structures.
• Electric conductors that connect the installations to a supply of electricity and other outside conductors and equipment on the premises.
• Optical fibre cable.
• Buildings used by the electric utility that is not an integral part of a generating plant, substation or control centre.

NEC 625, titled “Electric Vehicle Charging and Supply Equipment Systems”, provides the standards for off-board EV charging systems. It covers the infrastructure connected to either feeder or branch circuits for EV charging, such as conductors, connecting plugs and inductive charging devices, and provides the installation instructions for EV charging station equipment.

NEC 626. This standard, titled “Electrified Truck Parking Spaces”, covers the area of parking spaces for trucks. It defines the specifications for the electrical equipment and conductors external to the truck, which is used to charge the trucks. The specifications include circuit breakers, groundings, cable sizes, back feed prevention, etc.

Amongst EV apprehensions, battery fires and explosions incidents have caught considerable media attention [13]. This difficulty facing major manufacturers serves as a reminder that safety issues will prevail as battery costs are reduced and the auto industry handles range anxiety related to EVs. To reduce the probability of such occurrences, the industry must adopt best practices and safety regulations as well as the ideal combination of battery chemistry, cell design, and battery management system.

If used with sound risk management, lithium-ion batteries—and thus, EVs—are the safest technologies now on the market. Potential EV buyers are perplexed by terms like thermal runaway, spontaneous ignition, and battery management systems and become caught up in a maze of contradictory information about facts, figures, science, and business interests, which has an effect on their decision-making and the uptake of EVs.

The causes behind battery fires are an illustration of the absence of trustworthy information regarding EVs. Li-ion battery fires never occur on their own but are instead brought on by either physical injury, such as that sustained in a car accident or by the batteries heating up past their safe operating temperature, which could happen if the thermal management and battery management systems failed catastrophically at the same time.

However, improvements in single-crystal technology and passivating coatings on the cathode particle surface have dramatically increased the chemical stability of the cells even without cobalt. Different cathode chemistries have different threshold temperatures at which a rapid decomposition can occur.

In the case of a rare electric vehicle fire, liquid electrolyte combustion poses the greatest safety risk due to hydrogen fluoride gas being a product of such a reaction. This issue can be overcome by developing new non-flammable electrolytes, including future solid-state electrolytes [14].

4 Conclusions

With the advancement of EV technology, charging infrastructure and grid integration facilities, EV popularity is expected to increase significantly in the next decade. Therefore, further technological advances such as suitable smart charging infrastructure, reliable communication systems, and coordinated charging systems to quantify the impacts on the power grid are essential to ensure maximum benefits from EVs with distributed generators. Moreover, the Energy Internet could be a future grid technology, which will make the power system fully automated with advanced energy management systems.

This article discusses all the aspects of EV charging and grid integration infrastructure. Having unified standards for EVs and their charging infrastructure all over the world is a primary necessity for EVs to gain popularity in the market. The popular measures related to EV charging and grid integration are discussed elaborately so that future researchers can get a good picture of the specifications required to meet.

Besides, different aspects of the existing charging and grid integration infrastructure, such as the power, communication, control, and coordination, are reviewed rigorously with their advantages and drawbacks. A discussion on the prospect of EVs proves the necessity of having a review in this research area. We intend this article could provide a clear picture of the state of the art of EV charging and grid integration to the users and engineers.

5 References

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[8] The Pros and Cons of Public vs. At-Home EV Charging Stations

[9] How Much Do EV Charging Stations Cost? – Future Energy

[10] Chen, C. F., de Rubens, G. Z., Noel, L., Kester, J., & Sovacool, B. K. (2020). Assessing the socio-demographic, technical, economic and behavioral factors of Nordic electric vehicle adoption and the influence of vehicle-to-grid preferences. Renewable and Sustainable Energy Reviews, 121, 109692.

[11] Egnér, F., & Trosvik, L. (2018). Electric vehicle adoption in Sweden and the impact of local policy instruments. Energy policy, 121, 584-596.

[12] NFPA 70®: National Electrical Code®

[13] Forbes: Considering An Electric Car? Review The Risks And Learn How To Stay Safe

[14] Electric vehicle safety : concerns and considerations | Nickel Institute