OCPP

OCPP, the Open Charge Point Protocol, is a shared standard in which electric vehicle chargers and the cloud systems that run them exchange messages. A charger is a "charge point" and the cloud system is a "central system". Because both follow the standard, one charging network can run chargers from many makers.

Here is how it works in general. The charger connects to the central system over the internet. Both use a fixed set of messages. When a driver plugs in, the charger sends a message with the driver's card or app identity. The central system checks it and replies that charging is allowed. The charger then sends readings of the energy delivered during the session. At the end, the central system records the total for billing. The same messages let the operator change a price, limit the power or restart a charger from a distance.

OCPP does not cover payment, the plug or the power electronics. It covers only the messages. The charger starts the connection to the central system, which lets it work behind a router that blocks incoming connections. Two versions are widely used: 1.6 and 2.0.1. The newer version adds features such as better security and smart charging. Government guidelines for public chargers in India ask for open protocols, so that chargers from different makers can join one network.

Take, for example, a charging company with chargers from three different makers. Because all use OCPP, it can show them in one app and bill them in one system; see charging network software. Consider a driver who uses a phone app to start a session at a shopping mall; see EV charging apps. Say an operator wants to lower the power of every charger in a building during peak hours; see smart charging.

Without a standard, each maker would need its own software, and an operator would be tied to one maker, as described under lock-in. The chargers themselves are described in EV chargers, and a similar idea is the open standard for device connectivity.

How is it different from a charging plug standard? A plug standard decides the shape of the connector and the electric signals. OCPP decides the messages the charger sends to the cloud.