Case Study: Power in the Relay

Last Updated on 2025-10-29

Electricity grids were never designed for the modern world. They were built to carry power in one direction—from centralized plants out to homes and businesses. Today, however, the rise of renewable generation, electric vehicles, and heat pumps is reshaping the energy landscape. Utilities now face a far trickier balancing act: matching supply and demand in real time, across hundreds of thousands of endpoints.

In the Czech Republic, this challenge has prompted an ambitious rollout of a deceptively modest device: the WM Systems RelayBox. Behind its compact DIN-rail casing lies the ability to orchestrate demand response directly at the household level. With large-scale deployment already underway, RelayBox is rapidly becoming a cornerstone of smart grid strategy at ČEZ Distribuce.

A Regulatory Push for Smarter Energy Use

At the heart of this story is a regulatory framework designed to promote flexibility and smarter consumption. Under Czech energy rules, households with an annual consumption above 6 megawatt-hours (MWh) are encouraged to participate in load management programs.

These households typically operate energy-intensive equipment—heat pumps, boilers, photovoltaic systems, electric vehicle chargers—that exert significant stress on the grid. By enrolling them in structured demand response, ČEZ ensures that high-consumption homes become part of the solution rather than the problem. The RelayBox is the enabling technology, transforming conventional meters into tools of active grid management without requiring a full meter replacement.

This approach also aligns with EU Regulation 944/2019, which promotes demand response and consumer participation in energy markets. For ČEZ, RelayBox provides a pragmatic bridge between Brussels’ regulatory vision and the practical realities of Czech households.

The RelayBox itself is simple in concept yet powerful in application. It is a four-relay load control box that connects to the household’s electricity meter through a standard RJ12 interface. Using supported DLMS/COSEM commands pushed from the head-end system, the WM-RelayBox can remotely switch external appliances on and off.

• Relay 1 & 2 – Heat Pump and Boiler Room
  Thermal systems represent the largest portion of household energy use. By remotely cycling boilers and heat pumps, ČEZ can shave peaks and stagger loads, aligning demand with generation availability.
• Relay 3 – Photovoltaic Inverter
  The RelayBox can manage the export of energy from household solar panels, helping to maintain grid stability when local generation is high.
• Relay 4 – EV Charger
  Electric vehicles are both opportunity and challenge. With RelayBox, ČEZ can modulate charging to avoid spikes and steer EV load into periods of excess generation, such as windy nights or sunny afternoons.

The net effect is a system in which the grid operator gains fine-grained control, while households experience smoother service.

The Consumer Side: Data and Visibility

Participation is not just about giving utilities a “switch.” ČEZ also provides households with real-time consumption data through its digital platform.

• All users can access consumption information online, offering transparency into how and when they use electricity.
• In a limited pilot, some households received an in-home tablet device that displays usage data locally. This enhances awareness and can influence behavior directly, nudging consumers to shift activities like laundry or EV charging into off-peak hours.

This dual strategy—remote utility control plus consumer empowerment—creates a hybrid model of demand response. Rather than relying solely on top-down management, ČEZ fosters active participation.

Why This Matters: Matching Supply with Demand

RelayBox is more than a compliance tool; it represents a new paradigm of grid interactivity. By controlling the largest household loads, utilities can:

• Balance Renewables More Effectively
  Wind and solar power fluctuate. Turning heat pumps or EV chargers into flexible loads helps absorb excess generation when it is available.
• Prevent Local Grid Congestion
  Rooftop PV systems can flood local lines with reverse flows. The ability to manage export during stress periods protects voltage stability.
• Delay Costly Infrastructure Upgrades
  Instead of over-building substations and cables to handle worst-case peaks, utilities can smooth demand through targeted switching.

For consumers, the benefits include greater transparency, improved comfort, and the satisfaction of contributing to a more stable and sustainable energy system.

Challenges and Considerations

No transformation comes without frictions. The idea of utilities remotely controlling private household equipment raises important questions:

• Autonomy and Privacy
  Will consumers feel uneasy about ceding control of their heat pump or car charger? How transparent must utilities be to maintain trust?
• Reliability of Control
  Remote switching requires robust, secure communication. Cybersecurity becomes as important as physical grid hardware.
• Engagement
  Clear communication of the program’s benefits is essential for household participation and long-term acceptance.

These concerns are not unique to the Czech Republic—they reflect the global debate about how far utilities can and should reach into homes in the age of smart grids.

A Glimpse into Europe’s Energy Future

The RelayBox rollout in Czech households is not just a national project. It is a microcosm of Europe’s energy transition. Across the continent, DSOs (distribution system operators) are grappling with the same questions:

• How to integrate millions of decentralized renewable systems?
• How to prepare for mass EV adoption?
• How to manage rising peak demand without prohibitively expensive grid expansion?

WM Systems and the Scale of Deployment

For WM Systems, winning the ČEZ tender and supporting a large-scale rollout is a landmark achievement. It underscores the company’s ability to offer scalable, reliable solutions to grid challenges of national importance.

The project also highlights the role of mid-sized technology firms in Europe’s energy transition. Innovation does not only emerge from giant OEMs; agile specialists like WM Systems can supply precisely targeted solutions that reshape national programs.

Conclusion: A Choreography of Grid and Home

The Czech RelayBox story is about more than relays and regulations. It illustrates a deeper shift: the choreography of grid and household, where energy flows are no longer dictated solely by central plants but negotiated in real time across hundreds of thousands of endpoints.

Every time a boiler pauses or an EV charger slows, it is part of a collective dance balancing supply and demand. And while the RelayBox is just one instrument, in the hands of ČEZ it plays a crucial role in orchestrating this new energy symphony.

As Europe marches toward decarbonization, such projects provide a preview of the smart, interactive, and participatory grid of the future.