The Open Charge Point Protocol (OCPP) is an open-source protocol enabling communication between electric vehicle (EV) charging stations and a central management system known as a charging station network. Similar to telecommunications networks, this system is crucial for interoperability among different charging stations.

The OCPP protocol was introduced in 2009 by the Open Charge Alliance (OCA) to overcome fragmentation in the EV charging station landscape. Before this protocol, networks were limited by proprietary protocols, which restricted compatibility between providers. 

OCPP revolutionized the industry as an open-source standard, facilitating communication between charging stations and central management systems, enhancing integration and supporting large-scale network management.

There are several protocols related to OCPP:

• OCPI (Open Charge Point Interface) enables roaming across various charging networks, enhancing user experience.
• ISO 15118 supports Plug & Charge functionality and Vehicle-to-Grid (V2G) technology.
• OpenADR (Open Automated Demand Response) manages electricity demand during peak times.

Let’s take a look at each of them in further detail. 

Although OCPP focuses on communication between Charge Point Operators (CPO) and charging stations, there are related protocols. For example, Open Charge Point Interface (OCPI) manages communication between Mobility Service Providers (eMSP) and CPOs, facilitating roaming across networks. OCPI facilitates roaming between different networks, allowing drivers to access charging stations without creating multiple accounts. This functionality ensures a seamless user experience, regardless of the network the driver belongs to.

ISO 15118 is a communication protocol enabling Plug & Charge functionality and Vehicle-to-Grid (V2G) capabilities. Finally, OpenADR (Open Automated Demand Response) is a communication protocol that allows utility and grid managers to send signals to energy-consuming devices to manage electricity demand during peak usage or supply shortages.

Currently, the most commonly installed version of OCPP is version 1.6, which also marks an evolutionary milestone as it transitioned from the still-supported XML (SOAP) to JSON for message format, enhancing management aspects. This version has been further refined in the modern version 2.0.1, which is still slowly being adopted due to its lack of backward compatibility with version 1.6.

Key aspects defining OCPP include:

• Interoperability: OCPP facilitates communication between different charging station brands, avoiding vendor lock-in.
• Scalability and security: the protocol supports the management of large-scale stations' networks and includes security protocols such as TLS to protect data transmission.
• Smart charging and network management: OCPP enables smart charging, optimizing energy use by adjusting charging rates based on real-time conditions.
• Technical aspects of OCPP communication: OCPP dialogues are asynchronous, with request-response messages that are uniquely identifiable. This asynchronous nature helps manage network latency, ensuring smooth communication, which is especially important for large-scale implementations.

The protocol also provides for interactions between parties with retries and synchronization via timestamps to support the possible intermittency between the online and offline states of the parties involved.

OCPP has evolved from its initial release to the current version, 2.0.1, which includes advanced features like smart chargingsupport, V2G (Vehicle-to-Grid) integration and detailed security protocols. It has become the global standard for managing EV infrastructure, particularly in markets such as Europe and North America. 

OCPP 2.0.1 protocol also supports real-time pricing models and integration with renewable energy sources, proving essential for modern energy networks.

OCPP will likely continue to evolve to integrate more closely with the ISO 15118 standard, which includes features such as Plug & Charge. This allows vehicles to authenticate automatically and start charging sessions without RFID cards, mobile apps or QR codes. 

Integrating ISO 15118 with OCPP will further simplify the charging process and enhance V2G technology support, where vehicles can return energy to the grid during peak demand periods.