Today I attended the first Residential Flexibility conference by ElaadNL in Arnhem, the Netherlands. ElaadNL — well known for their testing work around smart EV charging — is expanding their scope to the entire home: heat pumps, home batteries, solar inverters and chargers, all coordinated by a Home Energy Management System (HEMS).
One language for all devices
At the core of the project: four protocols have been selected for communication between HEMS and devices — S2, EEBus, Matter and OCPP. Plus OpenADR for connecting the HEMS to the outside world. A deliberate choice to limit the number of standards, so manufacturers know what to build for and interoperability becomes achievable.
What impresses me most: ElaadNL is commissioning open source reference implementations for all these protocols, to be published on GitHub. This is a significant step. Open standards have existed for years, but without working code they remain paper tigers. By making reference implementations freely available, ElaadNL dramatically lowers the barrier for manufacturers to actually adopt these standards.
Modbus: today’s reality
A nuance I appreciate: Modbus is not being ignored. Many devices on the market — including bidirectional chargers — communicate via Modbus. It is not future-proof in terms of security, but it is the reality on the ground. ElaadNL is developing middleware solutions that allow Modbus devices to interface securely with a HEMS through the newer protocols. Pragmatic and realistic.
Why this matters
As the developer of V2G Liberty — a HEMS focused on bidirectional charging — I follow these developments closely. Interoperability is not a luxury, it is a prerequisite for scalable residential flexibility. Only when devices from different manufacturers can reliably communicate with each other does the promise of a smart home energy system become reality.
The fact that this initiative is backed by the Dutch grid operators, with support from the Ministry of Climate and Energy, gives it real weight. This is not a hobby project — this is infrastructure.
I look forward to the upcoming test events in June and October, and to the open source code being released.