Charging station for electric vehicles
Optimization in details
Charging modes
The optimized charging modes ensure efficient charging sessions and allow control of the charging sessions of the electric vehicle. Two charging modes are available. Green charging, in which almost exclusively self-produced energy is used, and fast charging, in which the vehicle is charged as quickly as possible.
For both charging modes, it can be set whether the energy from the battery (power storage system) should be used to charge the electric vehicle.
Green Charging
Ideally, in the 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 (single phase or three phase) of the connected vehicle.
In graph 1, it is cloudy from around 4 p.m. till 6:00 p.m., so that not enough PV energy can be produced to continue charging the vehicle. The Energy Management takes into account that the feature for charging the electric vehicle with energy from the battery is activated and decides to continue charging the vehicle during this period by discharging the battery and using a small amount of electricity from the public power grid. This prevents an interruption in the charging session, as displayed in graph 2.
Fast charging
In the 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 demand is covered by discharging the battery (power storage system) and consumption from the power grid, as displayed in graph 3. The Energy Management selects the energy resources that guarantee the fastest charging session. The charging current limit can be manually set in the ViCare app.
Note: The charging current limitation reduces the charging power of the electric vehicle. Reducing this limit can result in the vehicle no longer charging. Set a value that is higher than the minimum charging current of the vehicle.Overload protection
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 the 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 the 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.
