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EV Charging Industry Protocols and Standards

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August 27, 2023

The electric vehicle (EV) market is accelerating globally, with EV sales growing over 40% in 2021 despite chip shortages and supply chain issues. As electric cars become mainstream, charging infrastructure build-outs are ramping up to meet demand. Charging networks and automakers are rapidly innovating on EV charging technology. A key enabler of this growth is the development of protocols and standards that allow different vendors, networks, cars, and grid operators to interoperate seamlessly. Standardization helps future-proof investments in the dynamic EV ecosystem.

This article explores the most important EV charging protocols and standards that deliver the flexibility and functionality required for the industry’s continued expansion.

CCS – The Leading DC Fast Charging Standard

The Combined Charging System (CCS) has emerged as the dominant DC fast charging standard for EVs globally. Also known as “Combo charging”, CCS essentially combines AC and DC charging in a single connector by adding two high power DC pins to the existing Type 1 and Type 2 AC charging plugs. This results in the CCS Combo 1 standard used in North America and the CCS Combo 2 standard used in Europe.

EV Charging Industry Protocols and Standards

CCS connectors can deliver up to 350kW of power, allowing an EV battery to charge from 10% to 80% in under 30 minutes. Leading American and European automakers came together to develop CCS in 2012. It is now required for any public DC fast charging station receiving federal funding in the US. The EU mandated CCS for all new public charging points installed after 2014. Most major EV models like the Ford Mustang Mach-E, Volkswagen ID.4, and BMW iX are CCS-compatible. Over 21,000 CCS fast chargers have been installed in the US already.

Tesla Opens Up Its Ultrafast Connector as the North American Charging Standard

Tesla has built its own proprietary charging connector and Supercharger network that is incompatible with other EVs. While CCS chargers number in the tens of thousands, Tesla already has over 35,000 Superchargers worldwide. Recently, Tesla took steps to open up its connector design by making it an official standard called the North American Charging Standard (NACS). NACS can deliver up to 1MW of power, almost 3X more than CCS (Read more: Why is EV Charging Stations in Demand Today? ).

In late 2022, major automakers Ford and GM announced that they will support NACS in their upcoming EVs. This could make NACS a very common charging standard. Until NACS-native vehicles launch in 2025, GM and Ford owners will need to use an adapter to charge at Tesla stations. NACS will co-exist with CCS for the foreseeable future, giving North American EV drivers more charging options.

OCPP – Enabling Open Charging Station Management

The Open Charge Point Protocol (OCPP) has emerged as the open communication standard between EV charging stations and central management systems. OCPP allows station vendors and network operators to be interoperable regardless of hardware. The protocol is maintained by the Open Charge Alliance, a consortium of public and private EV stakeholders.

OCPP – Enabling Open Charging Station Management

OCPP enables remote management, smart charging, flexibility in pricing, remote diagnostics, software updates, and integration with utilities and grid operators. It gives charge point operators independence and control while avoiding vendor lock-in. OCPP has been implemented worldwide in over 5 million charging points to date. The latest OCPP 2.0.1 version adds new functionality for device management, security, transactions, and smart charging.

Plug & Charge with ISO 15118

ISO 15118 is the international standard that enables Plug & Charge, which allows EV drivers to simply plug in and charge without needing cards, apps or authentication. This is achieved by using a digital certificate that allows encrypted communication between the EV and charging station. ISO 15118 also enables bi-directional charging and discharging for vehicle-to-grid (V2G) applications.

Plug & Charge is being implemented in Europe currently, with drivers able to roam across borders seamlessly using just their EV. The latest iteration ISO 15118-20 defines an extended authentication protocol that adds more security. As Plug & Charge expands in the US, charging will become an invisible aspect of EV ownership.

EV Charging Industry Protocols and Standards to Enable Seamless Public Charging Roaming

For the public EV charging experience to be truly seamless, networks must support roaming between different charge point operators. Open roaming protocols allow drivers to easily charge across different networks without setting up multiple accounts.

The Open Charge Point Interface (OCPI) allows charge point operators to exchange data like real-time statuses and driver account details. The Open Clearing House Protocol (OCHP) goes a step further by enabling financial clearing of roaming charging sessions. OICP (Open Intercharge Protocol) and eMIP (eMobility Interoperation Protocol) are other roaming standards implemented in Europe. Roaming eliminates range anxiety and enhances the EV experience.

Smart Charging – Integrating EVs with the Grid

As EV adoption rises, charging stations are becoming intelligent assets that can be optimized based on real-time grid conditions. With bi-directional charging, vehicle batteries can even serve as storage and provide services back to the grid. Open protocols are enabling the integration of charging infrastructure with utilities and energy systems.

OpenADR (Open Automated Demand Response) allows utilities to manage charging stations and modulate demand dynamically during peak load conditions via “smart charging”. The recently introduced Open Smart Charging Protocol (OSCP) enables grid operators to optimize EV charging based on local grid capacity. These open standards are critical for managing EV growth in a sustainable way.

The Importance of Open Protocols for the EV Industry

The protocols discussed in this article highlight how standards enable interoperability between the various stakeholders in the EV ecosystem. Proprietary or “walled garden” systems inevitably limit innovation and leave customers stranded. Open protocols give customers choice while encouraging diverse products and services to flourish. As demonstrated by OCPP, open standards can gain tremendous traction when collectively embraced by the industry.

While the standards are still evolving quickly, companies build charging management platforms based on these open protocols to future-proof their customers’ investments.


Thanks to open standards, the EV charging experience is becoming seamless for drivers while integration challenges get abstracted away for charging providers. As charging networks expand globally, standards will be key to enabling roaming and interoperability across geographies.

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