The optimization feature “Smart EV Charging” ensures efficient charging sessions and is designed to give you control over the charging sessions of your electric vehicle. You can choose between two charging modes. Green charging, in which almost exclusively self-produced energy is used, and fast charging, in which the vehicle is charged as quickly as possible.
You also have the option of deciding whether stored energy from the battery (power storage system) should be used to charge the electric vehicle. This setting applies to both charging modes.
Charging modes
Green Charging
Ideally, in green charging mode, the electric vehicle is only charged with PV excess. However, strict adherence to the PV excess curve can lead to interruptions during the charging session, especially on cloudy days. To ensure a stable charging session, the vehicle is charged as long as the predicted charging self-sufficiency rate is above 90% and the charging current limit can be exceeded. This depends on the minimum charging current and the charging phases (1-phase, 3-phase) of the connected vehicle. As a result, the proportion of PV power that is charged into the vehicle for each charging session is at least 90% in green charging mode.
In the scenario displayed in graph 1, it is cloudy from around 5 p.m. till 6:30 p.m., so that not enough PV power can be produced to continue charging the vehicle. The algorithm of the optimization feature “Smart EV Charging” decides, taking into account the activated setting for charging with energy from the battery, that charging of the vehicle can be continued during this period by discharging the battery and a small amount of electricity from the public grid, thus preventing an interruption of the charging session, as shown in graph 2.
Fast charging
In fast charging mode the vehicle is charged as quickly as possible using all available resources. This means that in addition to the self-produced PV power from the photovoltaic system, the energy requirement is covered by discharging the battery (power storage system) and consumption from the grid, as shown in graph 3. The energy resources that guarantee the fastest charging session are selected. The charging current limit can be manually set to 6-16 A/phase in the ViCare app.
Please note that the charging current limitation reduces the charging power of your electric vehicle. Reducing this limit can result in your vehicle no longer charging. Set a value that is higher than the minimum charging current of the vehicle.
Overload protection
Without overload protection
The value of the maximum grid connection current has been exceeded and the house connection capacity has been overloaded.
With overload protection
The Viessmann Energy Management overload protection starts automatically and protects your house connection from overloading. If necessary, the charging power of the electric vehicle is dynamically reduced so that the charging session is carried out with the maximum possible power. At the same time, exceeding the maximum grid connection current is prevented to avoid tripping circuit breakers.︎
Note: The overload protection protects your house connection and optimizes the charging session, but does not replace general safety precautions such as circuit breakers against system damage caused by excessive currents.