Home battery: measure before you price it
The question is not what a battery costs, but how many kilowatt-hours you draw from the network between 17:00 and 22:00.
Updated on 14 September 2026
The one measurement that decides
A home battery pays back on a price gap, not on a quantity of energy. It lets you pay in ECO for what you would have paid in PEAK, and nothing more. The quantity that matters is therefore the number of kilowatt-hours actually drawn between 17:00 and 22:00 on an ordinary day.
That figure cannot be guessed. Two families of four in two identical houses can be a factor of two apart, depending on whether they cook with electricity, whether they have a car, and whether they are home at 18:00.
It gets measured, over two full weeks at least, winter included if the decision is meant to hold.
A battery creates nothing, it moves things
A battery does not produce electricity. It stores some, with losses, and gives it back later. If your five PEAK hours carry little, there is no gap to capture, and no amount of capacity will make the case work.
When that is what we find, we say so and we do not fit one. Scheduling a cylinder and a charge point costs a fraction of the price and takes the larger share of the gain.
Where a battery does defend itself is when it serves two purposes at once: avoiding the PEAK window in the evening, and keeping solar output that would otherwise leave for the network at midday.
What we record, and over what period
- Consumption from 17:00 to 22:00
- In kWh per day, over two weeks at least. That is the number that decides, and it comes before any catalogue.
- Peak power drawn
- It dictates the battery inverter, which has nothing to do with its capacity. A generous battery behind an undersized inverter will not carry the evening peak.
- Solar output, where there is any
- What leaves for the network between 11:00 and 17:00 is exactly what a battery would keep.
- The year the solar installation was certified
- Before 2024, compensation within each window runs to the end of 2030 and the arithmetic changes entirely.
- Space and ventilation
- A battery is a volume, a mass and a temperature limit before it is a number on a quotation.
Tell us what is in your consumer unit
Describe what sits on your board and we will say what can be shifted and what cannot. By phone on +32 495 88 75 92 or through the questionnaire.
Sources for this page
- CWaPE, press pack, new low-voltage distribution tariffs for 2026Checked on 2026-09-14
- Public Service of Wallonia, the two-rate schedule changes on 1 January 2026Checked on 2026-09-14