For those of you that might be wondering what OCPP and OCA are, let’s clear that up. OCA stands for the Open Charging Alliance. OCPP is Open Charge Point Protocol, the protocol used to facilitate communications between EV charging stations and central Back Office systems.
The OCPP is an open standard used internationally with no charge and no license requirements. The protocol was developed in 2009, and today it is used across the EV market by many significant players, including utility companies, manufacturers, back-office software suppliers, and Charge Point Operators (CPOs).
As it is an open standard, OCPP enables infrastructure operators and vendors to choose and supply EV Charging Stations to the operator of their choice. OCPP also allows companies such as Tridens Charge & Drive to create software solutions around this protocol.
OCPP is similar to IoT protocols in that it describes the messaging between Charging Station and IT Backends. These messages are used to give charging commands, track energy meter values, or authenticate new EV users.
Comparison of OCPP 2.0 and OCPP 1.6 for EV Charging Networks
Trends within the EV sector and the energy market drive changes to charging point backends’ standards and requirements. Software systems are increasing their levels of security, flexibility, functionality, and interoperability. ISO 15118 is one such innovation, describing the communication protocols between charging points and EVs.
OCPP offers a similar means of authentication as PKI – the standard used for secure website connection. It also provides more efficient means of data communication between charging stations and EVs.
Both OCPP 2.0 and 1.6 have well-developed smart charging functionality. OCPP 2.0, in particular, offers enhanced functionality for utility companies, EVSE owners, or CPOs.
OCPP 2.0 has been available since 2018. Although many EV charging systems are still using the previous version of the open protocol, OCPP 1.6, OCPP 2.0 is viewed as a key milestone in the EV market, and most manufacturers plan to switch as soon as they can.
Older versions of OCPP were hobbled by their inability to provide effective data communications. This lack of capability made them incompatible between many IoT devices and complex charging networks as the latter rely on using up-to-date device information. Such information includes data about any connected EVs, metering values, use identifications, and others. Only older communication protocols have sufficient data fields integrated flexibility of source code to allow software engineers to integrate a charging network.
Mature IoT communication Between Charge Points, EVs, and Backend Using OCPP 2.0
One significant improvement with OCPP 2.0 is the ability to request the amount of energy that an EV wants to charge in kWh. This figure is known as the requested energy amount. When an EV is connected to a charging point, it sends a requested energy amount to the charging point. It is crucial to note that this is only applicable to ISO 15118. The charging point then forwards this information (as a figure in kWh) to the central charging network. The charging network can then incorporate this information into a charging plan based on the overall requested energy amount.
This process is described in terms of “Charging with load leveling based on High-Level Communication” by OCPP. It refers to advanced usage rates of CSMS (Charging Station Management Systems) and EVSEs. The illustration below depicts the CSMS and EVSE primary communication process.
Steps 1-3 show how the requested energy amount gets used:
- Step 1. “ChargeParameterDiscoveryReq” message is sent from EV to Charging Station.
- Step 2. “NotifyEVChargingNeedsRequest” message is sent from Charging Station to CSMS.
- Step 3. “NotifyEVChargingNeedsResponse” message is sent from CSMS to Charging Station.
A “NotifyEVChargingNeedsRequest” is used to communicate charging needs from the EV to the CSMS, and it contains the following fields. Note that the “chargingNeeds” field includes the EV’s energy amount.
OCPP 1.6 has no means of supporting this field or sending requested energy amounts in absolute value format between charging points and OCPP backends. The older protocol only allows the SoC (State of Charge) to communicate in percentage terms. A report of 80% means that 20% of the battery’s capacity needs to be recharged.
SoC is a required data field. However, it places limitations on the amount of information contained on the OCPP backend. Regardless, there are still opportunities to implement Smart Charging procedures using OCPP 1.6. For instance, Tridens Charge & Drive has developed state-of-the-art interfaces for both OCPP 1.6 and 2.0 backends.