Electrical Vehicle Charging

Electric Vehicle Supply Equipment (EVSE, commonly referred to as electric vehicle chargers or EV chargers) is becoming a more common electrical load as EV demand rises. Most top automakers who sell to the US market have made commitments to dramatically increase production of electric vehicles within the next two decades. Designing systems with EVSE as a load requires several special considerations. This section will examine NEC requirements for electric vehicle supply equipment installations, types of electric vehicle chargers, an overview of standards to consider when specifying a charger or designing a system to support it, power distribution equipment to support EVSE installations, smart charging and charge management systems, and the emerging application of bidirectional charging.

NEC National Electric Code® Article 625 covers the electrical conductors and equipment connecting an electric vehicle to premises wiring for the purposes of charging, power export, or bidirectional power flow. To understand these requirements, the basic NEC definitions of Electric Vehicle Supply Equipment and related terms as provided in Article 100 must be understood.

Electric Vehicle: An automotive-type vehicle for on-road use, such as passenger automobiles, buses, trucks, vans, neighborhood electric vehicles, and electric motorcycles, primarily powered by an electric motor that draws current from a rechargeable storage battery, fuel cell, photovoltaic array, or other source of electric current. Plug-in hybrid electric vehicles (PHEV) are electric vehicles having a second source of native power.

Electric Vehicle Connector: A device that, when electrically coupled (conductive or inductive) to an electric vehicle inlet, establishes an electrical connection to the electric vehicle for power transfer and information exchange.

Electric Vehicle Power Export Equipment (EVPE): The equipment, including the outlet on the vehicle, that is used to provide electrical power at voltages greater than or equal to 30 Vac or 60 Vdc to loads external to the vehicle, using the vehicle as the source of supply.

Electric Vehicle Supply Equipment (EVSE): Equipment for plug-in charging, including the ungrounded, grounded, and equipment grounding conductors, and the electric vehicle connectors, attachment plugs, personnel protection system, and all other fittings, devices, power outlets, or apparatus installed specifically for the purpose of transferring energy between the premises wiring and the electric vehicle.

Wireless Power Transfer Equipment (WTPE): Equipment installed specifically for transferring energy between the premises wiring and the electric vehicle without physical electrical contact.

DCFC: DC Fast Charger, also referred to as Level 3.

Battery Management System (BMS)

• Regulates the current and voltage supplied to the battery and optimizes the charging process.

• Communicates with the vehicle’s onboard computer in-regards to the charging process.

• Monitors the charging process.

Electromagnetic Interference (EMI): EMI can disrupt the normal functioning of electronic systems in an EV, such as the audio, GPS, engine control unit, and more. It can also interfere with other electronic equipment nearby. Filters and shielding can be employed.

BESS: Battery Energy Storage System - Captures energy from renewable and non-renewable sources and stores it in rechargeable batteries for later use.

DER: Distributed Energy Resources - A distributed energy resource is any resource or technology that generates, stores, or manages energy at a local level, typically close to the point of consumption.

With these definitions in mind, NEC 625 includes standards for design considerations for power distribution equipment and energy management software, both of which will be discussed in greater detail later in this design guide. A selection of relevant sections is included in the following.

625.40 Electric Vehicle Branch Circuit. Each outlet installed for the purpose of supplying EVSE greater than 16 amperes or 120 volts shall be supplied by an individual branch circuit. Exception: Branch circuits shall be permitted to feed multiple EVSEs as permitted by 625.42(A) or (B).

625.41 Overcurrent Protection. Overcurrent protection for feeders and branch circuits supplying EVSE and WTPE, including bidirectional EVSE and WPTE, shall be sized for continuous duty and shall have a current rating of not less than 125 percent of the maximum load of the equipment. Where noncontinuous loads are supplied from the same feeder, the overcurrent device shall have a current rating of not less than the sum of the noncontinuous loads plus 125 percent of the continuous loads.

625.42 Rating. The EVSE shall have sufficient rating to supply the load served. Electric vehicle charging loads shall be considered to be continuous loads for the purposes of this article. Service and feeder shall be sized in accordance with the product ratings, unless the overall rating of the installation can be limited through controls as permitted by 625.42(A) or (B).

625.43 Disconnecting Means. For EVSE and WPTE rated more than 60 amperes or more than 150 volts to ground, the disconnecting means shall be provided and installed in a readily accessible location. If the disconnecting means is installed remote from the equipment, a plaque shall be installed on the equipment denoting the location of the disconnecting means. The disconnecting means shall be lockable open in accordance with 110.25.

625.48 Interactive Equipment. EVSE or WTPE that incorporates a power export function and that is part of an interactive system that serves as an optional standby system, an electric power production source, or a bidirectional power feed shall be listed and marked as suitable for that purpose. When used as an optional standby system, the requirements of Parts I and II of Article 702 shall apply; when used as an electric power production source, the requirements of Parts I and II of Article 705 shall apply. EVPE that provides a receptacle outlet as its point of power export shall be in accordance with 625.60.

625.49 Island Mode. EVPE and bidirectional EVSE that incorporate a power export function shall be permitted to be a part of an interconnected power system operating in island mode.

625.50 Location. The EVSE shall be located for direct electrical coupling of the EV connector (conductive or inductive) to the electric vehicle. Unless specifically listed and marked for the location, the coupling means of the EVSE shall be stored or located at a height of not less than 450 mm (18 in.) above the floor level for indoor locations or 600 mm (24 in.) above the grade level for outdoor locations. This requirement does not apply to portable EVSE constructed in accordance with 625.44(A).

625.54 Ground-Fault Circuit-Interrupter Protection for Personnel. All receptacles installed for the connection of electric vehicle charging shall have ground-fault circuit-interrupter protection for personnel.

Electric vehicles (EVs) use batteries as a power source for locomotion. The battery in the EV is a direct current (DC) device and must be recharged with DC power. However, most power distribution systems run on AC power. To get power from a traditional site’s electrical system to the EV battery, it must be rectified from AC to DC before reaching the battery. This can be accomplished in one of two ways: the power conversion can happen inside the vehicle using its onboard charger (AC charging) or externally to the vehicle (DC charging). The following diagrams illustrate how EV batteries can be charged.

The charging speed of an electric vehicle is determined by the limiting factor (lower kW rating) of the onboard and offboard charging systems.

The true instantaneous charging rate will vary depending on the battery’s charging curve, state of charge, internal and ambient temperature, and other factors. However, an approximation of total time to charge may be calculated thusly:

Two main considerations for EV charger selection will be discussed in this section. First, the power level of the EVSE, which determines how long it will take to recharge the EV battery. Second, the connector type, which is the interface for power and communications between the EVSE and the vehicle.

There are three widely used rates of EV charging: Level 1 AC, Level 2 AC, and Level 3 DCFC. Electric vehicles can be used with different EVSE depending on the rate of charge / charging dwell-time desired.

Level 1 provides charging through a standard 120 V outlet. It is common in residential applications. AC power travels to the vehicle’s on-board charger, which rectifies it to DC power to charge the EV battery. Level 1 charging adds two to five miles to the battery range per hour of charge, taking 40–50 hours to completely fill a vehicle battery.

Level 2 charging follows the same path as Level 1 charging (AC power -> onboard charger -> vehicle battery) through electric vehicle supply equipment (EVSE) rather than a standard 120 V outlet. The EVSE may be applied at 208/120 V or 240 Vac. The upstream overcurrent protective device for a Level 2 EVSE will be a two-pole breaker rated at least 125% of the rated EVSE current (e.g., a Level 2 EVSE rated for 30 A would be fed from a 40 A 2P breaker). Level 2 EVSE is commonly seen in residential, workplace, and public charging applications. They can fill an all-electric battery in 4–10 hours.

The following table approximates different dwell times and corresponding range added to an EV plugged into an AC Level 2 charger.

Average charging time of a typical electric passenger vehicle for a 25-mile trip:

DCFC Level 3 Direct Current Fast Charge (DCFC) equipment is the fastest way to charge an EV battery due to its higher kW rating. DCFC EVSE power ratings range from 20 kW up to 350 kW. Instead of using the vehicle’s onboard charger to convert from AC to DC, the DCFC EVSE takes care of the power conversion and pushes DC power to an onboard DC/DC converter then directly to the vehicle battery.

DCFC is typically fed from 480 V 3P breakers. DC fast chargers are typically installed along highways for public use, or for fleet vehicles or car dealerships that need a quick charging turnaround. DCFC can get a battery from zero to 80% in as little as 20 minutes.

There are two commonly available configurations for DCFC: Standalone or “All In One” systems and Split systems.

Standalone (SA): or “All in One” systems normally < 240 kWpp (max around 480 kW). Modules combined with charger.

Split systems: Separated dispenser and power module cabinet. Normally 150 kW-360 kW max pp (max 500 kW) but similar architecture for MW. Shared power amongst multiple dispensers, normally (1–8 ports), some systems are scalable with additional modules or cabinets.

Connectors

In addition to different rates of charging, connector type is a consideration when selecting an EV charger. In North America, the most common standards are SAE J1772 for AC charging and Combined Charging Standard 1 (CCS1) for DC charging, or the North American Charging Standard (NACS, formerly known as Tesla) for both AC and DC charging. Some vehicles, like older models of the Nissan Leaf, use a CHAdeMO connector, but these are being phased out.

Nearly one million EVs on the road at the beginning of 2024 use J1772 for AC charging and CCS1 for DC charging. However, now that NACS is available for vehicles other than Tesla, many automakers will be switching to the NACS connector and standard. Ford, GM, VW Group (including Audi and Porsche), BMW Group, Mercedes-Benz, Hyundai, Genesis, Kia, Mazda, Nissan/Infiniti, Toyota/Lexus, Subaru, Volvo, Polestar, Lucid, Fisker, and Rivian have all committed to using the NACS configuration in 2025.

CCS1

This 7-pin EV plug is used for DCFC charging (up to 350 kW) in North America, although it can also be used for slow AC charging. Essentially, the CCS1 is a SAE J1772 plug with two additional high-speed DC charging pins added.

CCS2

The European counterpart of the CCS1 is a 9-pin enhancement of the Mennekes plug. It allows charging of up to 350 kW. As with the CCS1, this plug can deliver both AC and DC charging.

CHAdeMO

Initially developed in Japan, the 10-pin CHAdeMO was one of the first fast-charging DC plug types on the market. The first generation offered up to 50 kW, and the second generation expanded to 400 kW. Despite its popularity in Japan, the plug is being phased out internationally, particularly since the European Commission mandated CCS2 for DC charging in Europe.

GB/T

GB/T is the standard AC and DC plug in China, delivering 7.4 kW for AC and 237.5 kW for DC. It is used by around half the electric vehicles in the world today but is not used in North America.

North American Charging Standard (NACS)

Tesla’s formerly proprietary EV plug accommodates Level 1, 2 and 3 AC and DC charging. In other words, there is just the one plug. In Europe, Tesla cars now use CCS2 charging.

As manufacturers switch their plug standard and the industry evolves, adaptors and cable kits help drivers use a multitude of EV chargers. All Tesla vehicles come with an adapter that connects to the J1772 plug. An adaptor that goes the other way, allowing J1772/CCS1 vehicles to use NACS chargers, is also available. Many charging companies are also offering the option to retrofit their stations with a new cord to keep up with the industry’s increased adoption of NACS.

Industry standards are changing rapidly as this growing industry evolves. There are published and developing standards regarding conductive and inductive charging, unidirectional charging and bidirectional power transfer, charger construction and safety, communication, cybersecurity, and more. The Electric Vehicle Charging Standards table below classifies various standards pertinent to electric vehicle charging systems but is not intended to be comprehensive. Many local, state, and regional jurisdictions may also be relevant.

The integration of EV charging supply equipment requires the integration of several high-power loads and an adaptation to the existing electrical infrastructure. This section presents basic principles for designing the EV charging infrastructure and its integration into an existing electrical installation.

For more information on power distribution equipment options, please see the Power Distribution Equipment section of this design guide. For EVSE applications, the focus will be on low voltage equipment: panelboards, switchboards, and dry-type transformers.

The first consideration for power distribution equipment is how the EVSE will get their power.

Different charging levels require different power distribution equipment.

Utility metering required, unless fed from internal facility feeder.

Common use cases:

Scenario 1: A power system study has determined that there is sufficient capacity in the existing system to add the EVSE specified for the site.

If the number of charging points and their capacity is significantly lower than the installed power, an option to investigate could be to integrate the EV chargers into the existing electrical installation, as shown in the following.

It is important to perform a power system study to ensure the power load can be added to the existing electrical infrastructure. Energy efficiency measures could be proposed to reduce the existing consumption and therefore increase the power demand that can be added. Local power supplies and storage could be proposed to compensate for the impact of integrating the EV charging equipment. If the existing LV switchboard cannot accommodate the additional power and/or devices required, the option described in next paragraph is recommended.

As specified in NEC Section 625, the power distribution equipment feeding the EVSE shall have sufficient rating to supply the load served. Overcurrent protection for feeders and branch circuits supplying electric vehicle supply equipment shall be sized for continuous duty and shall have a rating of not less than 125 percent of the maximum load of the electric vehicle supply equipment. Electric vehicle charging loads shall be considered continuous loads unless an automatic load management system is used, in which case the maximum equipment load on a service and feeder shall be the maximum load permitted by the automatic load management system. This section assumes that an automatic load management system is not present. More information about automatic load management systems and smart charging may be found in the Charge Management Software section.

Municipal guidelines should be consulted for new construction projects involving parking to determine the minimum number of spaces that need EVSE. Some utilities offer special rates for EV charging installations. To be eligible for the EV tariff, utility requirements may specify a dedicated meter for the EV chargers.

Remembering charger types:

• AC Level 2 chargers are typically rated for installation in 208/120 V systems or 240 V systems. Most require a 2P breaker as OCPD.

• DCFC will typically be fed from a 480 V 3P breaker.

For example, consider a site with (10) Level 2 chargers rated 7.2 kW / 30 A. For each breaker rating, find 125% of the EVSE’s current rating:

30 A * 1.25 = 37.5 A

The OCPD for each of the chargers will be the next highest available standard size: 40 A.

A 208/120 V panelboard to feed these (10) chargers may have a panel schedule like this:

The total connected load is 62400 VA, or 173.2 A. The next highest main breaker size would be 200 A.

The Scenario 1 example and variations presented below cover the addition of EVSE to sites with existing power distribution systems. Many existing businesses and sites are retrofitting and/or adding to their existing systems to accommodate the demand for EVSE.

If the power demand of the new EV loads is equivalent to or higher than that of the existing electrical installation, it could be preferable to install a new main LV switchboard to integrate all EV loads. The existing electrical infrastructure will be connected to this new main LV switchboard. A power system study should be performed to ensure overcurrent protective device coordination between the existing installation feeder and the new main incoming device.

If there are several EV chargers located at the same area, secondary LV switchboards or panelboards could be installed close to the EV charging area to minimize the cable length.

The creation of a new main LV switchboard presents the advantage of minimizing the changes to the existing electrical installation. In addition, it offers the opportunity to coordinate protection devices and thus optimize the power availability.

The integration of EV loads increases the power demand of the electrical installation significantly. An extension of the local energy infrastructure is often required. A switch from a LV grid connection to a MV grid connection could be necessary in certain cases.

In addition to the electrical infrastructure, the electricity contract with the energy provider needs to be reviewed.

To limit or avoid these types of significant modifications to the existing local installation, local energy power supplies can be added, such as:

• Photovoltaic system: for local energy production and a commitment to sustainability.

• Energy storage system: to avoid power demand peaks and optimize solar production use.

• Combined heat and power (CHP): combined heat and power production if relevant.

Local power supplies can be connected to the new main LV switchboard. Their integration into an existing electrical infrastructure requires a preliminary audit.

Example solution for a parking structure.

I-Line Busway

800–5000 A busway

Aluminum and/or Copper

Plug-in or bolt-on disconnects

30 A, 60 A, 100 A, 200 A, 400 A, 600 A + plug-in circuit breaker disconnects

Fusible or circuit breaker plug-in units

Circuit breakers with electronic trip unit (ETU), communications (Ethernet or Modbus)

Charge Management Software (CMS) communicates directly with the EV chargers for monitoring and control. Automatic load management systems can alleviate the impact of EV installations by setting a maximum power limit for a group of EVSE. This software is also how equipment owners can bill for charger usage and drive ROI on their EVSE investment.

Key terms:

• Smart chargers are internet enabled hardware units that work with software management to provide the best driver and owner experience. Smart chargers are also required hardware when applying for incentives.

• Software management enables you and your clients to have complete control of your charging program, reduce costs, capture incentives, and ensure a positive ROI and driver experience.

• Load Management Software balances the existing output capability among the energy-consuming assets in a building or business. Linked directly to a site’s electrical capacity. Works with smart charging and demand response.

• Demand Response is implemented at the power company level.

As illustrated in the following, there are different communication protocols between the electric vehicle (EV) and the electric vehicle supply equipment (EVSE), and between the EVSE and the CMS.

ISO 15118 is a set of protocols that allow EVs to communicate with charging stations. ISO 15118-2 pertains to network and application protocol requirements for communication between electric vehicles and charging stations.

• Plug & Charge – A standardized, secure authentication process where an EV automatically identifies itself to the charging station, initiating and authorizing charging without requiring user interaction (such as RFID cards or apps).​

• AutoCharge – A simpler method for automatic charging session initiation based on the vehicle’s MAC address. AutoCharge starts charging when the vehicle is recognized by the charging station.

Open Charge Point Protocol (OCPP) is an open communication protocol that allows EV charging stations to communicate with central management systems. There are several versions currently available and in development.

• OCPP 1.6 – Widely used, supports basic smart charging and device management.​

• OCPP 2.0.1 – Introduces enhanced security, plug-and-charge, and better support for energy management.​

• OCPP 2.1 – Vehicle-to-grid (V2G) support.

It is important to specify the correct OCPP firmware revision on the charger to ensure that the desired EVSE and CMS are compatible. Typical language may read, “must support OCPP 1.6J or later with smart charging profiles. To ensure compatibility, charger must undergo certification testing with EVConnect.”

Smart chargers must be able to communicate via internet, wired or wireless, and support web socket communication. Commonly specified communications capabilities are WiFi 802.11 at 2.4 GHz for wireless network communication, Ethernet 10/100, and 4G LTE Cellular connectivity with a sim card that may or may not be swappable in the field. Some users prefer to also specify EVSE that is capable of a local list support or freevend offline/non-network mode fallback configuration.

Cybersecurity is an important consideration with any connected product. One way to ensure safety when specifying a smart charger is to specify that the EVSE must include a trusted platform module (TPM) developed using an IEC 62443 compliant reference framework for cybersecurity.

In order to provide accurate data to the CMS, the EVSE should include an imbedded submeter for measurement and reporting of electricity delivered to the EVSE. ±1% accuracy is a commonly specified value for the internal meter.

There are extensive possibilities for monitoring, control, and logging with charge management software. Commonly specified features include remote monitoring and control, cost calculations, and charge history. Knowing what you can manage and how is key to helping your clients understand why software management is necessary with their EV charging program if full ownership of the solution with complete visibility and control is desired.

There are many ways you and/or your clients may want to manage charging. You may want to manage unique driver groups differently, encourage increased utilization by implementing overstay fees, know when it is time to add more stations because the current allotment is being fully used, or address issues quickly to optimize the driver experience.

You will also want to bill drivers correctly for the energy they use and save money by managing on and off-peak energy utilization. Many energy providers charge you significantly more according to the peak amount you consume in a given time period. As such, doing things that spike the site’s load will cause a jump in the bill.

Managing all of this can sound daunting, but it does not need to be. You can provide a solution that does not take hours and hours each week to monitor and adjust. A good software management platform will enable you to set it up, track progress, understand utilization, view revenue, and track key metrics you and/or your clients need for reporting in a simple, easy to understand dashboard.

The management system will need to enable your EV charging program to operate within your site’s current electrical capacity and with your local energy provider’s capacity, not against it.

The electric grid is fragile and as climate change increases, we are seeing more failures. How will a shift to electric vehicles affect this? In 2019, Americans drove roughly 9 billion miles per day. A “high efficiency” electric vehicle gets about 4 miles per kilowatt-hour. So, that is an average nationwide daily energy use of 2.25 billion kilowatt-hours. Meanwhile, nationwide energy use comes to about 10.6 billion kilowatt-hours per day. In other words, EVs would up demand on the grid by 20%.

Moreover, vehicle charging is more difficult to manage. The grid needs to be able to “predict” high demand times to stay stable. An additional 2.25 billion kilowatt-hours of consumption spread across people’s varied schedules creates substantial difficulty.

Demand pricing and grid balancing are about when electricity is consumed, along with how much is consumed. Demand will go up with electric vehicles, so load management focuses on controlling the “when.” But load management systems also take on another issue: distribution of electricity through all EVs plugged into a system.

By managing these two variables in tandem, load management systems reduce costs for the person using them and protect the local grid, all by managing when electricity is consumed, how much is used and where those amounts go. The ability to manage how much power is being used is critical in minimizing grid failures and optimizing a positive driver experience.

Load management ensures clients avoid costly infrastructure and services upgrades by managing how much electricity they need to bring to their panel to power their chargers. This is critical for setting yourself and clients up for a shorter ROI.

Let us say there is a need for 30 chargers, but only enough room on the panel for 6. Load management will enable you install all 30 chargers by oversubscribing the panel without fear of going over electrical limits. You and your clients can avoid service upgrades, new transformers, panel upgrades or replacements, etc., saving 10’s or 100’s of thousands of dollars and streamlining the project timeline. This also makes your bids more competitive than others who do not have a firm grasp of this concept.

Load management systems operate in different ways. Most focus on three qualities: controlling when electricity is used, where it goes and how much goes to each vehicle, all with minimal effort on the part of the user.

Types of Load Limits: EV Connect supports both current and power limits in setting charging profiles.

• Current Limit (A): Limiting the maximum amperage of a group of stations based on the size of the upstream circuit breaker or panel.

• Power Limit (kW): Limiting the maximum power (kW) of a group of stations served by one transformer.

• Some sites are also subject a utility rate that requires aggregate load stay below a power threshold.

Load Balancing Logic: Load is balanced in near real time using two mechanisms: Proportional or Fleet.

• Proportional Load Sharing - Each active session is provided a proportional percentage of the available power limit, scaled by the rated capacity of charging stations.

In general, a client will be able to prioritize different elements. For instance, you can prioritize reducing energy cost by instructing the system to charge vehicles separately throughout the night, with a maximum consumption limit. This allows you to ensure that each vehicle is charged as much as possible without threatening the electrical grid or risking high demand charges. Some can even be programmed to consume more electricity when the grid has more capacity than demand, allowing users to make use of that gap while assisting the electrical grid.

Using the example above, let us say your client has all 30 chargers installed off 6 circuits – each with capacity for 1 charger. When driver 1 plugs in, they will get 100% of the power. When driver 2 plugs in, both cars will get 50%. When driver 3 plugs in, all three get 33%, and so on for each circuit. Ideal for scenarios where drivers are parked for long duration, you can see how this has a positive impact on your client’s infrastructure costs and charging capacity.

These systems are remarkably simple to use, too. You select peak power or energy usage and tell the system how to judge that amount: either by the total amount consumed or amount used over a specific period of time or make the amount responsive to grid demand. You then set power-sharing settings, picking certain amounts for each vehicle, or using a first-in, first-out system.

Here’s how load management uses software to maximize the site’s current infrastructure:

If such solution is not installed, the installation should be sized for the maximum power demand without considering charging period and usage coefficient. As consequence, the installation will be oversized versus the real need, and the costs of the EV charging infrastructure will be higher.

So, as you can see, without software, you cannot design an optimal charging program, and therefore cannot maximize a charging program for yourself or a client. ROI is contingent on reducing your up-front infrastructure costs, capturing incentives, managing pricing or time of use, enabling driver groups, and billing them accurately, tracking utilization, increasing uptime, and operating within the grid capacity you have.

With software, all of this is possible. With EV Connect, all of this easy.

By partnering with EV Connect, you are choosing a partner who empowers you to power your client’s EV charging programs. We put you in the driver’s seat to build, manage, service, track and grow the right solution for your clients and prospects. We understand that your success is directly tied to your ability to easily provide competitive quotes, limit time needed to set-up, service and manage chargers, and be the expert your clients are looking to when they want to offer EV charging.

While there are basic power management software platforms for any building site, it makes the most sense to communicate with the experts at EV Connect to discuss your power management needs. Working in tandem with demand response from the power company, smart charging, software management and power management have the potential to significantly reduce your site costs. Not to mention this helps ensure a sustainable future for EVs if sites can continue to maximize the potential of their existing power infrastructure.

Sources

1. Energuide.BE – Why Does the Electrical Grid Have To Stay in Balance?

2. Kelly Blue Book – Average Miles Driven Per Year: Why It’s Important

3. Select Car Leasing – Miles Per KwH - The New MPG

4. Energy Information Administration (EIA) – Electricity Consumption in the United States Was About 3.9 Trillion Kilowatthours (kWh) in 2021

5. Schneider Electric – What Is a Power Management System, and How Does It Help Optimize Uptime and Efficiency?

6. EnergyStar.Gov – Activating Power Management: Commercial Software Packages

7. Environmental Leader – Electric Vehicle Charging Generating Growth in Building Energy Management Systems

8. McKinsey – Charging electric-vehicle fleets: How to seize the emerging opportunity

Bidirectional Charging refers to systems that are capable of power flow in two directions: the power to charge the battery in an electric vehicle, as discussed earlier in this section, and reverse power flow from the electric vehicle battery back to the rest of the system. Bidirectional charging requires an EV capable of reverse power flow, EVSE capable of bidirectional power flow, and software to communicate with and manage all the components.

ISO 15118-20 is the ISO 15118 standards document that pertains to vehicle to grid communication standards.

Bidirectional charging is sometimes referred to as V2X or “vehicle to everything” charging. There are also specific types of bidirectional charging discussed in the following.

• Vehicle to grid (V2G): Through a converter that is usually present in the charger, vehicles can send energy directly back to the grid. This can facilitate more energy efficiency for a local power grid and lead to cost savings by enabling charger owners to get paid for helping maintain grid reliability.

• Vehicle to home (V2H): Bidirectional V2H charging turns a car battery into a backup power source for a home. This also allows for more efficient energy usage and potential cost savings and typically relies on technology that is built into the charger.

• Vehicle to load (V2L): The EV battery can be used to power appliances and tools on the go. This type of charging relies on vehicles that have built-in converters and 120-volt plugs for charging appliances and devices.

• Vehicle to vehicle (V2V): A specific application of V2L charging where the load is another electric vehicle. V2L allows the transfer of energy from one car to another.

By creating this two-way energy stream, bidirectional charging offers several benefits to EV owners, both in terms of potential savings and energy efficiency.

1. Save Money on Energy Use

   Bidirectional charging unlocks potential savings for vehicle owners in two ways. First, smart-charging technology, coupled with bidirectional charging, can turn a car into an efficient power source for a home or business. The vehicle charging can be set to charge during off-peak hours or when renewable sources are available.

   Second, with vehicle-to-grid technology, you can sell energy back to the utility company for redistribution. This can further reduce your utility costs. One study by the University of Rochester found that V2G chargers can save EV owners $120 to $150 per year.

2. Store Backup Power for Your Home or Business

   Beyond cost savings, bidirectional charging can also provide peace of mind for homeowners and business owners. If you are caught in a power outage, V2H charging allows your vehicle to serve as a backup power source while the utility company conducts repairs. The typical electric car battery holds about 60 kilowatt-hours of electricity, which is enough to power a home for roughly two days.

3. Create a Portable Power Source

   Thanks to bidirectional technology, in some cases, that same battery that can power your home can also go on the road with you to serve as a mobile power source. If you take your EV camping or out on the job, for instance, you can use it to power appliances. In a pinch, you could even use it to provide energy for someone else’s car.

Sources:

1. Autotrends – What Is Bidirectional Charging?

2. University of Rochester – Can Electric Cars Help Strengthen Electrical Grids?

3. World Resources Institute – How California Can Use Electric Vehicles To Keep the Lights On

4. Clean Energy Reviews – Bidirectional Chargers Explained - V2G Vs V2H Vs V2L