Load management in electromobility
Significance and functioning of load management in e-mobility
December 12, 2022
If you want to install not one, but several wallboxes or charging stations, you will come across the term "load management". But how does load management work in electromobility and what is the difference between static load management, dynamic load management and schedule-based load management? Here we give you an introduction.
Want to learn more? Then download our whitepaper on load management!
How does load management work?
Load management controls the power demand to maintain a nearly constant, balanced power level and avoid load peaks and spikes. In other words, load management balances the building installation, the available total connected load, the other energy requirements of the building and the energy requirements of the charging stations. Load management also helps you to use electricity from your photovoltaic system specifically for charging.
Load management hardware
Load management does not work without the appropriate hardware. The control unit can either be installed in the charging station or be an external module. There is often a hardware limitation of the controllable charging stations, which is in the range of 16 devices.
Load management and concurrency factor
The so-called "consumers" - for example, ovens, air conditioners or televisions - are not in operation all the time, nor are they always at full power. To correctly determine the total connected load to be planned, the simultaneity factor is used to determine the maximum energy demand. This results from the sum of the maximum demand of all consumers multiplied by their simultaneity factors.
Load management ensures that the simultaneity factor is maintained when several users are simultaneously connected to wallboxes or charging stations. For example, the simultaneity factor of the charging stations can be reduced to 0.2 or even 0.1 - i.e., 20 % or 10 % of their theoretical maximum demand - so that enough energy is still available for other consumers at the grid connection. Load management distributes the available power among the charging points. This available power is either statically determined during installation or dynamically determined with an energy meter.
The different types of load management in electromobility
We distinguish between static, dynamic and schedule-based load management. If a constant power is to be distributed, static load management is sufficient. If the available power fluctuates a lot, you should use dynamic load management. If certain vehicles need to be up and running again more quickly than others, schedule-based load management is recommended.
Static load management
With static load management, you specify an available power at installation. This is then distributed evenly among the connected charging points. Such a solution is uncomplicated to set up and comparatively inexpensive due to the less complex hardware.
The disadvantage is the inflexible use of electricity. For example, more charging power is not made available at night when less power is needed by the other consumers.
Dynamic load management in electromobility
With the dynamic load management of a wallbox or charging station, the currently available power is determined with an energy meter and dynamically distributed to the connected charging points. Depending on the power consumption in the building and the time of day, you make optimal use of the power currently available. However, the complex hardware is also somewhat more expensive.
Schedule-based load management
Schedule-based load management is mainly relevant for vehicle fleets. Depending on when a particular vehicle must be ready to drive, load management provides different charging services depending on the charging point.
Load management and photovoltaic power
Closely related to load management is charging with self-generated electricity. With PV surplus charging, you only charge when the PV system generates enough energy and all other consumers in the building are supplied.
If a predefined value - 1.4 kW for single-phase charging and 4.1 kW for three-phase charging - is reached or exceeded, the inverter sends a start signal to your charging station to start the charging process. If the value is fallen short of, the charging process stops. The prerequisite is a charging station that understands the start and stop signal of the inverter.
In addition, the control of a private wallbox with charging management works through a Home Energy Management System (HEMS). This is part of dynamic load management and is a separate topic.
What are the costs of load management in electromobility?
The cost of load management depends on the charging solution chosen. For less than EUR 800 each, you can already get wallboxes with integrated (static) leader-follower load management. For example, the Heidelberg Wallbox Energy Control.
In addition, there are costs for professional installation. This must be carried out by a specialist electrical company. For commercial use in (semi)public spaces, charging stations such as the Amperfied connect.publicwhich also support dynamic load management and are often part of a larger project with corresponding infrastructure.
You want to learn more?
Then download our detailed whitepaper on load management here!
What you can expect, among other things:
- What are the implications of not using load management?
- What does the concurrency factor mean and why is it so important for planning charging infrastructure?
- What do Modbus and OCPP stand for and what are the advantages of using them?
- How does load management work in combination with a Home Energy System (HEMS)?