The iberian blackout

On April 28, 2025, the Iberian Peninsula experienced the most severe power blackout in its recent history, affecting more than 60 million people in Spain, Portugal, Andorra, and southern France. At 12:33 (CEST), a sudden loss of approximately 15,000 megawatts of power, equivalent to 60% of Spain's electricity production at the time, caused a grid collapse that spread to connected regions.

While the debates revolve around causes and responsibilities, we will, as always, on this newsletter analyze the role that heat pumps can play in the stability and resilience of the electrical system.

⚡ An electrical system under tension: structural problems

• High penetration of renewable with low inertia:

Renewable energies, such as solar photovoltaic, lack the rotating components found in thermal or hydroelectric plants, which act as a "flywheel" for the grid. This means that in the event of any disturbance, the system frequency drops more quickly and the margin for reaction is smaller.

• Lack of operational flexibility:

The grid's ability to adapt to rapid changes in generation or demand is limited. Spain and Portugal have made significant progress in renewable capacity, but not at the same pace in storage, flexible demand management, or rapid response capacity.

• Poor interconnection with the rest of Europe:

Currently, electricity exchange capacity with France is around 2-3%, well below the European target of 15%. This means that, in the event of an imbalance, the peninsula cannot rely sufficiently on external grids to stabilize.

🔁 Do heat pumps help solve the problems?

Of all the problems mentioned, the role where the heat pump could help is in providing inertia. Do heat pumps help solve the problem of low system inertia? Not directly. Heat pumps do not provide electrical inertia to the system because they are not rotating generators that can stabilize the frequency. They are not a solution to the physical problem of the lack of rotating mass in the grid.

However, they can indirectly help mitigate its effects in three ways:

• Flexible demand response:

Unlike other HVAC systems, heat pumps can be integrated with home automation and smart systems that allow their operation to be adjusted in real time, depending on grid conditions. This means that, in the event of a disturbance, the load could be reduced (or increased) in a coordinated manner, helping to stabilize the grid without the need to generate more electricity. Most of heat pumps are already smart grid and it can answer signals from the utility networks.

• Passive thermal storage:

Although they do not generate electricity or stabilize the grid directly, buildings that use heat pumps are generally better insulated and have a greater capacity to retain heating or cooling. This allows them to "hold" power for longer periods of time without power, reducing peak demand during emergencies or grid recoveries.

• Combination with PV + battery:

In homes with a heat pump, photovoltaic self consumption, and batteries, it is possible to operate in island mode temporarily. These homes not only cease to be a burden on the grid at critical times, but could even (in the future) inject energy or provide flexibility if the system is prepared for it.

There are also specific technologies already mentioned in this bulletin, where the role of PV and the heat pump can be thermal storage. If we increase the setpoint of all our services, such as a DHW tank, a buffer tank (heating/cooling, or both if we have two buffer tanks), a pool, or, in direct installations, the storage can be carried out in the home itself.

Lessons from the blackout

The big lesson from the blackout shouldn't just be directed at consumers. It's a clear message for system operators, grid planners, and energy authorities, resilience depends not only on large backup systems, but also on how demand is managed and how distributed technology is integrated into the entire system.

Heat pumps, combined with self-consumption and storage, are more than an efficient alternative for the home, they can be a strategic tool for the electricity grid of the future.

As is mentioned above, heat pumps don't replace the inertia provided by traditional power plants, but they are part of the architecture of a modern and resilient grid, one that doesn't rely exclusively on centralized generation and takes advantage of the distributed flexibility of millions of small players.