Why the home battery is so popular

More and more Dutch households have solar panels on their roofs. That’s great news, as it allows you to generate your own green electricity. Until now, homeowners could take advantage of the net-metering scheme: electricity generated during the day could be taken back from the grid for free in the evening. However, that scheme is being phased out by 2027. As a result, many people want to store their own power so they can use it at a later time.

A home battery seems like a logical step, but such a battery is expensive (averaging around €8,000), uses scarce raw materials, and has a long payback period. Moreover, many batteries charging and discharging at the same time create new peaks on the power grid. That is exactly what we want to avoid in a future-proof energy system. That is why more and more people are looking at smart alternatives.

Your home as a thermal battery

Heat pumps use electricity to extract heat from the outside air and bring it indoors. That in itself is already more energy-efficient than heating with gas. But with smart control, you can go a step further: you can generate heat at the right moment and store it temporarily, so you don't have to use (expensive) power from the grid later on.

This utilizes the thermal mass of your home and a hot water tank.

How exactly does such a home battery work?

The house uses its own mass—the concrete floor, walls, radiators, and the hot water tank—to retain heat. Think of it as a kind of XL pizza stone combined with a large thermos. The smart software in our heat pumps, Weheat Intelligence, makes this possible.

Here is how it works:

1. When electricity is cheap or free, the system heats up the floors, walls, and the domestic hot water tank. ‍
2. When rates peak, the pump switches off. The stored heat does the work. ‍
3. The temperature remains stable, and the family doesn't notice a thing. Except for their energy bill.

Generation
If you have solar panels, you often generate more electricity than you are using at that moment. A smart heat pump uses that time to heat water. Don't have panels? Then you can choose low-cost electricity hours (for example, at night or during the day) via dynamic energy tariffs.
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Storage
The generated heat is stored in two forms:

• In a boiler tank: the water heated by the heat pump is stored there for later use.
• In the thermal mass of your home: in the (underfloor) heating, walls, or a concrete floor that retain heat and release it slowly. ‍

Usage
Later in the day, when electricity is more expensive, you use this stored heat to warm your home. Without needing to switch the heat pump back on.

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Why this is smart and sustainable

You use electricity at times when it is cheap and (usually) green, which helps you avoid peak loads in the evening. This not only lowers your energy bill but also relieves pressure on the power grid. This is exactly what legislation in countries like the United Kingdom is now driving toward: smart, demand-driven home energy storage.

Moreover, you don't need to invest in an expensive home battery made from scarce raw materials like lithium and cobalt. You simply use water, concrete, and the smart software in your heat pump. This is how you contribute to a sustainable energy system without unnecessary hardware.

Real results, thoroughly tested

You might be thinking, "Sounds good, but does it actually work in practice?" Our engineers thought so too. That’s why they tested it, for a year Not in a test setup, but in a real home that is constantly in use: the house of our very own Dave!

Some highlights from the test:

51% of all generated solar energy was used directly (instead of 17%) ‍

46% less energy fed back into the grid = significantly less strain on the power grid ‍

34% lower energy bill compared to a 'dumb' thermostat in a 2027 scenario

Download the Use Case! Gain insight into all the data from the test year and discover how this smart idea works in practice.