Stuurbox or EMS API: What Do You Need for Smart Energy Management?
Published by
Teun van Sinten
Covolt Netherlands
You want to get more out of your solar panels, battery, or charging infrastructure. You’ve heard about Covolt and you’re excited, but then the practical question arises: Do I need to replace my existing control box, or can I just connect it?
The answer depends on what you already have. And the good news is: in most cases, you won’t need to replace anything. Covolt offers two options. In this article, we’ll explain the difference—without the jargon—so you’ll know exactly which one is right for your situation.
Covolt now manages more than 900 installations in the Netherlands and Belgium. The question “control box or EMS API?” is one of the most frequently asked questions at the start of a partnership. So by now, we know the answer well.
First, let's understand: what does a steering box actually do?
A control box is a local hardware device located at your energy installation. The box communicates in real time with your inverters, batteries, power meters, and charging stations, and executes control commands based on signals from a central platform such as Covolt Horizon.
Without a control box, there is no local control. That means: no automatic response to negative energy prices, no optimization of self-consumption, and no real-time adjustments during grid congestion.
The control box is, therefore, the link between the cloud-based intelligence and your physical on-site installation. Covolt Horizon thinks; the control box acts.
What's the difference? — At a glance
|
Compare the options |
Covolt Control Box Control via proprietary hardware | EMS API Integration with your existing system |
|---|---|---|
| Hardware Required | Covolt installs on-site | No replacement |
| Connection | 4G SIM card — independent | Via an existing connection |
| Response time | Real-time, local | Via the cloud |
| Existing control box | Replacement or new | Remains unchanged |
| Brands | Covolt's own hardware | including Envitron, With the Grid, Embion, among others |
| Installation | On-site by Covolt | Remotely by Covolt |
| Market Access | Entirely through Covolt Horizon | Partly through Covolt Horizon |
The Covolt Horizon Control Box
The Covolt Horizon Control Box is proprietary hardware developed by Covolt. We install it on-site at your facility. Using its own 4G connection with a dedicated SIM card, the Control Box serves as a fast and secure bridge between your facility and the Covolt Horizon platform.
The main advantages of the Control Box are its local response speed, access to Multimarket energy trading, and self-consumption optimization. Even if the internet connection at the site is lost, the Control Box continues to function and local control remains possible. For installations where a stable connection is essential—such as during aFRR activations—this makes a real difference.
The right choice if
- You don't have a control box installed yet
- You're launching a new facility and want maximum market access
- You want to optimize your self-consumption
- You want a reliable connection that is independent of the local network
Covolt handles the entire installation and commissioning process on-site. Once the system is connected, Covolt takes full responsibility for its operation and monitoring.
The Covolt Horizon EMS API
The EMS API is not hardware but a software interface. If you already have a control box from another brand—such as Envitron, Embion, or With the Grid—you can connect directly to the Covolt Horizon platform via the EMS API.
Your existing control box stays in place. Covolt sends all control commands to your hardware via the API. You keep your own system; Covolt provides the intelligence and control.
The right choice if
- You already have a steering box from another brand
- You don't want to or don't need to replace your existing hardware
- You'll want to take advantage of Covolt's control system for PV and imbalance trading on your battery
The EMS API does not require on-site installation. Covolt handles the technical integration remotely.
No matter which option you choose, through the Covolt Horizon platform you’ll benefit from Covolt’s control of your PV system in both cases, and we can manage your battery to address imbalances. In addition, the MyHorizon App gives you access to real-time monitoring and monthly reports. With our proprietary control box, you gain even more capabilities: self-consumption optimization, trading on the day-ahead market, participation in aFRR, and congestion management services via GOPACS.
Which connection method is right for your system?
Question 1 of 2
Do you already have a control box on your system?
A control box manages the operation of your system.
Question 2 of 2
Do you actively participate in aFRR or other fast balancing markets?
In fast-moving balancing markets, the response speed of your system is important. Covolt evaluates which control system is best suited to your system and market participation.
Question 2 of 2
Would you like us to take care of everything for you, including on-site installation?
The Control Box is a complete solution: Covolt supplies the hardware, installs it, and then takes over all control and monitoring.
Your assessment
The Covolt Horizon EMS API seems like a good fit for your situation.
Your existing control box stays in place. Covolt connects via the API and provides market optimization and power control — without any new hardware.
Covolt checks in advance whether your current system is technically compatible. We handle the integration remotely— no on-site installer is needed.
Your assessment
The Covolt Horizon Control Box seems like a good fit for your situation.
Covolt installs the hardware on-site and then takes over all control and monitoring. You don't have to do anything yourself.
The Control Box operates via its own 4G connection using its own SIM card—completely independent of the local network at your location.
Your assessment
Consider the Control Box as an upgrade.
You already have a control box. To participate in fast balancing markets, it makes sense to consider whether local control would be a better fit for your installation.
During a consultation, Covolt will discuss whether switching to the Control Box makes sense for your specific installation. There’s no obligation.
Frequently Asked Questions
What is the difference between the Covolt Control Box and the EMS API?
The Covolt Control Box is proprietary hardware that is installed on-site at your facility and connects to the platform via 4G. The EMS API is a software interface that allows you to connect your existing control box from another brand to Covolt Horizon without replacing any hardware.
Will the EMS API work with my current control box?
Yes. Covolt connects to control boxes from Envitron, With the Grid, Embion, and others via the EMS API. Please schedule a consultation to find out if your specific make and model are compatible.
Does Covolt need to come on-site for the EMS API?
No. For the EMS API, Covolt handles the technical integration remotely. For the Control Box, however, Covolt does handle the on-site installation.
Can I switch from the EMS API to the Control Box later?
Yes. If you decide later that you want to switch to the Covolt Control Box—for example, to improve local response speed—that’s possible. Covolt will discuss this during the consultation.
