ElaadNL and Flexiblepower Alliance Network (FAN) are excited to announce the selected parties to develop open source software for accelerating an interoperable ecosystem for Home Energy Management Systems and flexible energy-intensive devices: Inversable, Computime and enjoyelec. These three companies will develop open source implementations of the protocols S2 (Inversable), Matter and OCPP (Computime), EEbus (enjoyelec) and a Modbus converter (Inversable). Via the open source implementation of these protocols, secure, reliable, and standardized communication across multiple devices and vendors is enabled, supporting both local and cloud-based Home Energy Management deployments. To ensure high code quality and reduce the risk of bugs and vulnerabilities, ElaadNL and FAN are working closely with the European Network for Cyber Security (ENCS) throughout the development process.
In the changing energy system there is a growing demand for flexibility in the domestic domain, harnessing the flexibility of smart, grid-intensive appliances in and around home (like charging stations for electric cars, heat pumps, home batteries and solar panels). These appliances can be intelligently controlled with a HEMS (Home Energy Management System). This allows for maximizing the utilization of locally generated solar power. It also allows electricity demand to be spread over a longer period, to reduce grid load, or to be shifted completely to times when there is less grid demand. This improves the reliability of the electricity grid, accelerates household decarbonisation and reduces the societal costs for grid management. Smart energy management also helps households save on energy costs by using self-generated energy directly, by aligning consumption with real-time electricity prices through dynamic energy tariffs and in the near future by optimizing their grid tariffs.
A big obstacle in the current market for both flexible energy-intensive devices (FEIDS) and Home Energy Management Systems (HEMS) is that there is no standard way of working for the communication between these smart devices and the HEMS. Besides that, there is no uniform way to communicate signals from outside the house to the HEMS. As a result, consumers can feel forced to limit their purchases to specific brands (vendor lock in) or be at risk for a suboptimal power usage within their homes.
Without a standardised, uniform communication between FEID and HEMS, consumers lack opportunities to respond to incentives that are already available or due to be released, such as energy contracts with dynamic tariffs, a feedback tariff for locally produced electricity, the end of the so called salderingsregeling* (net metering) and the introduction of Time of Use grid tariffs (expected in 2028 in the Netherlands).
A market survey commissioned by ElaadNL and FAN showed there were already more than 25 different protocols for in-home interoperability in the market, with no clear vision on the way forward. This obscurity is a burden for Original Equipment Manufacturers (OEMs), because in the current market they need to either develop their products for a broad variety of communication forms, take a guess (and therefore a risk) for a limited set, or develop their own, proprietary, software. One of the recommendations in the market survey, was to increase the long-term interoperability by focussing on four already available protocols: S2, Matter, EEbus, OCPP for in-home communication and OpenADR to connect the HEMS to the outside world. OEMs can choose to incorporate only one of the four selected FEID protocols, whereas the HEMS will need to incorporate all four. Once this is realised all FEIDs will be interoperable with all HEMS, enabling full flexibility for the end users.
In July 24, 2025 a tender was opened for the development of open-source software to enable communication between energy-intensive devices and Home Energy Management Systems. Almost 20 offers were received, ranging from a selection of the scope to full coverage of all topics requested. After an extensive evaluation by a panel of experts from ElaadNL, FAN and industry specialists the following parties have been awarded contracts to deliver the key components of the interoperability roadmap:
These organizations will deliver open source software to ensure secure, reliable, and standardized communication across multiple devices and vendors, supporting both local and cloud-based HEMS deployments. To ensure secure implementations and strengthen trust in the interoperable ecosystem, all code will be scanned and reviewed by the European Network for Cyber Security (ENCS) before publication.
Arjan Wargers, manager Innovation at ElaadNL: “The quality of all offers we received was very high. This indicates the broad interest in the topic in the market. Selecting our dream team made for an energetic start of this important work!”
Ethan Zhu, CEO at enjoyelec: “We are excited to collaborate with ElaadNL and the Flexiblepower Alliance Network to strengthen the interoperability roadmap. Our focus is to bring EEBUS into a robust, open-source implementation that partners can adopt with confidence—accelerating an open ecosystem where devices and HEMS work seamlessly together.”
Computime Group Chairman, Executive Director and CEO – Mr. Bernard Auyang: “We are proud to contribute to this landmark initiative by ElaadNL. Open standards are the foundation for a truly interoperable energy ecosystem, enabling households to take control of their energy usage and support a more sustainable future.”
Erwin Bisschop, Co-founder Inversable: “Inversable is committed to open source solutions for the energy transition, and is excited to contribute to this project, together with our embedded partner PrimeConnect. We look forward to taking this important new step with ElaadNL, manufacturers, and the other parties involved.”
Besides work on the dedicated work packages, the participating companies will also play a major role in a series of test events that starts February 12th and 13th at the ElaadNL Testlab in Arnhem. During the test events, the current performance and remaining research areas of hardware and software brought by participants can be tested against other market products in an easy to enter environment. Each event will be accompanied by a conference. The aim is to reach an industry certification for interoperable FEIDs and HEMS by the end of 2026.
For more information about the project and its roadmap, visit Residential interoperability • Projecten • ElaadNL
* ‘Salderingsregeling’ (net metering) is a method that allows consumers to even out their electricity production and consumption on their energy bill, regardless of the moment in time at which energy was produced or consumed.
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