Is it worth investing in a home battery?

What should be done with the energy generated at midday when the house is empty and it is not possible to consume it all? In 2026, the answer is no longer a simple "yes" or "no". It depends on your lifestyle, the layout of your home and your vision for the future. Between promises of autonomy and budgetary realities, here is a comprehensive analysis to help you make an informed decision.

To assess the viability of a battery, it is first necessary to understand what is being paid for. Today, the average price of electricity on the grid is around €0.35/kWh. But this amount hides a complex reality: the energy itself represents only a fraction of the price. The rest is made up of transmission and distribution charges and various taxes.

In Belgium, the "compensation" mechanism (the meter that runs backwards) is a thing of the past. While some older owners retain their advantages, new buyers enter directly into the self-consumption regime. From now on, every kilowatt-hour you feed into the grid is bought back at a much lower price (around €0.04/kWh) than the price you pay for it (€0.35/kWh).

The calculation is simple: every kWh that you manage to store at home for later consumption saves you nearly €0.31/kWh. It is this difference that is the main driver of your profitability.

In the world of storage, size matters, but not in the way you might think. When exploring current quotes, one figure often comes up: 10 kWh capacity. This is no coincidence, but a balance between cost, domestic needs and technical constraints.

Small batteries (3 to 5 kWh) are proportionally much more expensive to install. Fixed costs for labour, certification and the hybrid inverter weigh heavily on the bill. Conversely, once you reach a capacity of 10 kWh, the price per kilowatt-hour installed becomes much more attractive, falling to around €750/kWh.

This is why the 10 kWh model is often used as a benchmark in comparisons: it currently offers the best value for money for a standard household equipped with a heat pump or electric vehicle.

Examples of average prices per capacity (inverters and installation costs included):

NB : If your current solar installation is already equipped with a compatible hybrid inverter (one inverter for both the panels and the battery), you could reduce these amounts by €1,500 to €2,500, which significantly improves your return on investment!

Adapting to your consumption profile

Choosing your capacity means anticipating your needs. A small battery will be enough to cover electronic standby consumption and lighting. A more generous capacity will allow you to power energy-intensive appliances (washing machine, cooking, heating) throughout the evening, thus avoiding drawing on the grid when rates are highest. 

However, be careful not to oversize: a battery that is too large for your solar production will never be profitable, as it will remain partially empty for half the year.

To choose the right battery, it's not just a question of how much energy you produce. You need to know whether your panels actually generate enough surplus energy to fill it, even during less sunny periods. To do this, it's useful to think in terms of kWh injected.

Let's take the example of our 10 kWh reference battery again. To fill it while covering the basic needs of the house during the day, you should ideally have a total surplus of 2,500 kWh injected per year.

Investing in a battery in 2026 is a marathon, not a sprint. With an average cost of €7,500 for a 10 kWh reference unit, the return on investment time is approximately 12 years in our scenario.

Scenario for a 10 kWh battery

* Averages

Factors to consider

Several factors can influence the length of the return on investment:

• Recharge when prices are low: Current systems can charge the battery from the grid during off-peak hours and discharge it during peak hours (or when prices are negative if you have a dynamic rate).
• Taxation: In Belgium, homes over 10 years old still benefit from a reduced VAT rate of 6%, which significantly reduces the return on investment time.
• You already have a hybrid inverter: In this specific case, even with VAT at 21%, your ROI falls to around 10 years for the above scenario.
• Capacity rate: If you live in Flanders, your battery also helps you reduce your "capacity tariff" by smoothing out your consumption peaks. In Brussels, this advantage does not yet exist for private individuals: profitability is based mainly on direct savings per kWh consumed.
• Subsidies: There are currently no purchase subsidies for domestic batteries. The authorities believe that public support should focus on production and insulation.

More profitable than savings

But will the battery die before it has been paid for? In 2026, the answer is reassuring: the lifespan of a quality battery far exceeds its return on investment (ROI).

Most experts agree on a useful life of 15 to 20 years. With a financial break-even point reached in around 12 years (including replacement of the inverter), you benefit from a net ‘profit window’ of approximately 3 to 8 years after the installation has been fully paid off.

Over the total lifetime of the project, this represents an average annual return of around 3% to 3.5%. This is a rather attractive performance when you consider that your savings account (1-2%) or government bonds (2-3%) tend to take a nap while your battery works under your roof.

While current Lithium-ion batteries (lithium ferrophosphate technology - LFP) are already extremely reliable, the storage sector is undergoing rapid change. Here's what the future holds.

The sodium-ion revolution

By the end of the decade, we will see the emergence of sodium batteries. Cheaper to produce because they use sea salt rather than lithium, they could bring storage prices down by 20 to 30%.

Solid-state batteries

Expected in the early 2030s, these batteries promise double the energy density and absolute safety (no risk of fire). They will be able to store 20 kWh in the same space as a current 10 kWh battery.

Vehicle-to-Home (V2H)

Your next electric car could well be your home battery. Bidirectional technology allows your vehicle to feed electricity back into your home. However, this will not make stationary batteries obsolete: a home battery is still needed to manage daily life when the car is not there.