A wallbox charges, an energy management system decides when and how strongly. Here you learn what an EMS is, which solutions exist and which one you really need.
Not always. With one wallbox, no solar installation and one car, you usually do not need an energy management system. As soon as you want to use your own solar power, run several charge points or also have a heat pump or battery, a control system that coordinates everything is worthwhile.
An energy management system (EMS) is the control centre of the house. It measures in real time how much power the solar installation produces and how much the house consumes, and tells the wallbox how much power it may charge with. This needs a measuring point, usually a smart meter at the grid connection. An EMS can sit in the inverter of the solar installation, in the wallbox itself, or be added as a separate device or online service.
A wallbox on its own simply starts charging as soon as you plug in the car. The EMS decides when and how strongly.
The car charges with the power your solar installation currently has left over. There are three levels: with manual control you set the charging power yourself. With automatic control the wallbox starts above a defined minimum surplus and charges at constant power. With dynamic control the charging power continuously follows the actual surplus, and start and stop happen on their own. On a single phase you need at least about 1.4 kW of surplus (6 A at 230 V), below that the wallbox pauses. Wallboxes that switch automatically between single-phase and three-phase charge on three phases when there is plenty of sun, from about 4.1 kW.
Here the system protects your house connection and fuses. If the heat pump, the oven and the wallbox run at the same time, the charging power is reduced so that nothing trips. With several charge points, the system distributes the available power among all vehicles.
You specify by when the car should be charged to what level. The control chooses the period and the power, for example a cheaper electricity tariff or the sunny hours.
Grid operators can require that charging stations can be switched off in a critical grid state. EKZ names a contact for load shedding for this, which a local load management system can also pick up centrally.
A selection by type of solution. This is not a ranking and not a purchase recommendation, we have not tested the devices ourselves. The information comes from the manufacturers.
| Approach | Examples | In its favour | What to check |
|---|---|---|---|
| Wallbox and inverter from one manufacturer | Fronius Wattpilot with a Fronius inverter and smart meter; SMA EV Charger with Sunny Home Manager 2.0 | Everything in one system, surplus charging and phase switching are provided for | Tied to the manufacturer. The Wattpilot needs a Fronius inverter with a smart meter (or Fronius accessories at the feed-in point). Without a Home Manager, the SMA EV Charger only works as a normal wallbox. |
| Open software | evcc (open source), possibly with Home Assistant | Works with many wallboxes and inverters. The modes “Min+PV” (charge immediately at minimum power, increase when there is surplus) and “PV only” | Developed by volunteers, with no guarantee of functionality. Check the device list in the documentation first. Setting it up takes some technical skill. |
| Swiss energy managers and cloud | Solar Manager; smart-me (meters and cloud with servers in Switzerland); Ecocoach ecoChargingCoach | Provider and support in Switzerland. Ecocoach works with several brands, and according to the manufacturer the basic version manages up to ten AC charging stations | Ongoing costs (for example an annual subscription, at smart-me extended functions are part of the Professional subscription) and cloud dependency. Ask the provider for prices. |
| Load management for several charge points | Zaptec (Go with Sense and smart meter, Pro for large installations); Easee | Distributes power across many cars. Zaptec Go can control up to three charge points dynamically with Sense and a smart meter. Easee states up to 30 cars on a 63 A connection. | Manufacturer information. Billing between the parties is a topic of its own and often runs via additional services. |
Usually no EMS. What matters is a three-phase supply line (the VSE advises against household sockets for charging), the connection application to the grid operator and an electrical contractor who installs it. A simple time control of the wallbox is usually enough.
You need three things: a smart meter at the grid connection point, a wallbox with stepless control (ideally with switching between single-phase and three-phase) and an interface to an EMS, for example Modbus RTU or TCP, EEBus, WLAN or LAN. The EMS can be the manager of your inverter manufacturer, evcc or a Swiss energy manager.
A central EMS that knows all large consumers is worthwhile here. Before buying, check which devices it can actually control and whether your heat pump and battery are supported by your manufacturer.
Dynamic load management is common here because the house connection often does not suffice for all charge points at the same time. Four cars with 11 kW each would draw 44 kW together. The system throttles and distributes, so the connection is never overloaded and an expensive upgrade can often be avoided. In a self-consumption community (ZEV, possible since 2018), load management is often part of the solution. How you get a charging station as a tenant is explained in the article on wallboxes in rented and co-owned property.
An EMS is not a must, but with your own solar installation it is the lever that lets your car charge with cheap power of your own. Start with the question of which devices you already have: if inverter and wallbox come from the same manufacturer, its manager is often the simplest way. With mixed hardware, open solutions and Swiss energy managers are an option. With several charge points you need load management anyway.
More on this: Smart charging and grid relief, Charging: at home or in public with the wallbox selection, Compare charging costs properly and Bidirectional charging.
Sources: manufacturer information and documentation (Fronius, SMA, evcc, smart-me, Ecocoach, Zaptec, Easee), EKZ leaflet, VSE information sheet. As of October 2026. We have not tested the products mentioned. Functions, prices and compatibility change, please check them before you buy. Product and brand names belong to their respective owners. This article does not replace advice from an electrical contractor.
