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The home battery: an interesting investment

The home battery: an interesting investment

Since Elon Musk, Tesla's big boss, came out with the home battery about four years ago, things have been moving fast for this home storage battery. In the meantime, numerous brands brought their own version of the home battery onto the market.

Recently, a ruling by the Constitutional Court decided that, in Flanders, the principle of the reverse electricity meter for solar injection will disappear from existing solar panel installations. Anyone who has had a digital meter since 2020 will be charged an injection rate for the excess solar energy that they 'inject' back into the grid. Those who still have a traditional (reverse) electricity meter currently pay a prosumer rate. Last year, the Flemish government also introduced a purchase premium for home batteries. One condition is that the inverter is set in such a way that it never injects more than 60% of your electricity production into the grid. As a result, the interest in and demand for home batteries is once again growing sharply.

But what exactly does such a battery involve? Is it a profitable investment?


What is a home battery?

A home battery is a large battery that can be installed in private homes to store electricity. The battery is usually connected to solar panels because, that way, you can store the free energy from the sun for evenings and nights when the sun is not shining. The capacity of home batteries is expressed in kWh. Most home batteries have a capacity between 2.2 kWh and 14kWh.

A home battery offers the option of storing at home the energy generated by your solar panels during the day.

Optimum enjoyment of your own solar energy

The number of households with solar panels continues to increase in Belgium. When the sun shines brightly, solar panels sometimes produce more energy than a family needs at that point in time. Conversely, in the winter months there may not be enough sunshine when energy consumption in the home is at its highest: mornings and evenings.

Zonnepanelen thuisbatterij

Which size home battery should you choose?

That depends on the production capacity of your solar panels and the electricity consumption generated by the home. The solar panels provide 25-30% for self-consumption. With a home battery, this can be increased to an average of 75%. The inverter at the solar panels can never inject more than 60% of your electricity production into the grid. This means that your home battery must be large enough to store at least 40% of your production at any time, even in summer. 

The purpose of your home battery is to use a much larger part of your own solar energy. And thereby maximise energy bill savings.

A home battery is also perfect to store the power for your electric car. So you can truly drive on your own green electricity. A welcome bonus: during power cuts, your home battery ensures that your most important appliances (e.g. freezer, alarm system, laptop, and smartphone) continue to be supplied with electricity.

Thuisbatterij investering


A home battery can also be considered an emergency solution, like generators in hospitals. Thanks to the energy stored in the battery, appliances and lighting in the home can continue to operate in case of a (protracted) power failure. How long you can use it depends, of course, on the capacity of the installed home battery, the battery's state of charge at the time of the power cut, and the devices to be supplied with electricity. Not all home batteries have this feature. This feature usually requires an additional technical component and thus entails a more complex installation.

Save on your prosumer rate

In Flanders

Anyone in Flanders with solar panels on their roof pays a yearly prosumer rate (link in dutch). In fact, you are both a producer (you inject your surplus electricity into the grid) and a consumer (when the sun is not shining, you draw electricity from the grid). If you coordinate this well, the final reading on your meter will be close to zero. This will make it appear as if you are not using the grid, when in fact you are a dual user of the power grid. That is the reason why the Flemish government introduced the flat-rate prosumer rate, depending on the capacity of your solar installation and the region you live in.

If you choose to use a home battery, then it would be wise to swap the reverse meter for a bidirectional meter. This measures exactly how much electricity you are actually consuming and injecting into the grid. Thus, you only pay taxes and transport costs for the limited amount of surplus energy that you feed into the grid. The prosumer rate therefore falls away.

On 1 January 2022, the method of calculating the grid cost on the electricity bill will also change. The new so-called capacity rate will take into account the consumption peaks of households or homes. A home battery will thus help you to use as much energy from the solar panels as possible. Less power will then be taken from the grid, reducing the risk of 'peaks'. This represents an additional saving, this time on the 'capacity rate'.

So, certainly in Flanders, a home battery is becoming more interesting than before.

In Wallonia

There is currently no prosumer rate in Wallonia (link in French). Thus, solar panel owners don't pay extra to inject their excess solar power into the grid. However, that is about to change. As of 1 January 2020, the Walloon government will also introduce the prosumer rate.

In Brussels

As in Wallonia, the Brussels Region does not have a prosumer rate. From 2020 onwards, legislation will change, but in a different manner than in Wallonia. Thus, owners will receive a lower rate for the excess power they feed into the grid.

Is a home battery a smart investment?

The cost of a home battery depends on a range of factors, such as the brand and capacity. The higher the capacity, both in terms of load capacity and the speed at which the power can be supplied, the higher the price tag. You can easily expect to pay 5,000 to 8,000 euros for a good quality battery. This hefty sum currently does not make it possible for a home battery to pay for itself in the same way as solar panels (8 years on average). Currently, it takes on average 20 years for a home battery to become profitable.

Energy specialists predict that the home battery will soon become a standard feature.

For the time being, this payback period is only valid for Flanders (if the prosumer rate falls away with the installation of a bidirectional meter). In Brussels and Wallonia, investing in a home battery does not currently provide any financial benefits. Because, as a solar panel owner, you can actually use the electricity grid as a battery at no extra cost.

Nevertheless, energy specialists predict that the home battery will soon become a standard feature.

Especially now, when battery prices are falling, the technology is becoming more accurate, and legislators are gearing up for change. We are closely following the news about home batteries! There is even a chance that the Flemish government will grant a premium for purchasing a home battery.

TIP: When you buy a home battery, check whether the take-back obligation (battery recycling cost) has been taken care of!

Like all other batteries, home batteries are subject to the take-back or acceptance obligation by the producer/importer.

This is regulated at European level. The manufacturer/producer must provide the possibility of returning the home battery to the manufacturer via the installer.

Manufacturer/producer is the company that puts the batteries on the Belgian market and thus has the take-back obligation in Belgium.

Thuisbatterij recycleren

The advantage of this is that the manufacturer/producer knows best how their own home batteries are made. Therefore, they are better placed to recycle or reuse their batteries in other applications, if this is technically possible. The take-back costs are anticipated by the manufacturers/producers who are members of Bebat. At the end of the home battery's life, you can return it free of charge to the sales network from which you purchased it.  The take-back cost for recycling a home battery that easily weighs 100 kg can, depending on its chemical composition, be as much as 350 euros.

It’s certainly worth enquiring with the seller about this.

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