Since 2019 and until March 31, 2023, residents of the Flemish Region are entitled to a bonus for installing household batteries. These make it possible to store the energy produced by the solar panels when it is not consumed. This stored energy can then be used, in the evening for example. But while these batteries are still very expensive today, no premium exists in Wallonia and Brussels.
However, the purchase of domestic batteries could be very useful in coping with the rise in electricity prices and guaranteeing citizens autonomy in terms of energy production.
Bonus: up to 40% of the total purchase amount
A domestic battery costs around 8000 euros for a capacity of 10 kWh. The bonus for the purchase of a domestic battery was introduced by Flanders in 2019. The amount of this bonus currently amounts to €225 per kWh for household batteries with a capacity of up to 4 kWh. From 4 to 6 kWh, citizens receive an additional €187.5 per kWh. Beyond 6 kWh, this bonus is €150 per kWh, up to a maximum of 9 kWh. The amount of the premium cannot exceed a total amount of €1,725 or 40% of the invoice.
This system will end on March 31 to make way for new financial compensation: the Flemish Minister for Energy, Zuhal Demir (N-VA), has in fact announced that she wants to double the premium for the installation of a heater. thermodynamic water. In the meantime, the success of domestic batteries is on the agenda in the north of the country: in 2021, approximately 18.000 dossiers were introduced to get this premium and more 23,000 requests were made in 2022.
A bonus in Wallonia and Brussels: profitable?
In Wallonia as in Brussels, no bonus exists for the moment. If Walloon citizens who own photovoltaic panels still benefit from the meter which is running backwards, the days of this compensation mechanism are however numbered. In 2024, no new installation will be able to benefit from it. Only Walloon households with solar panels before January 1, 2024 will still be able to benefit from them until 2030. Domestic batteries could then become very useful for preserving production autonomy, without going through the network.
In Brussels, as in Flanders, there is the injection tariff (this special tariff paid by the suppliers for the electricity injected into the network). Household batteries can therefore already be interesting for saving money.
However, without the establishment of a bonus as in Flanders, the high cost of batteries will be difficult to amortize. Currently, batteries are rarely profitable before 8 years of use. Their lifespan is 15 years. And this damping problem may not be resolved quickly: “From January 2024, it will be profitable between 6 to 7 years for small batteries and rather between 5 to 6 years for large batteries”raises Matthieu Wuidar, managing the company Noveway, specialized in the installation of photovoltaic panels and that of domestic batteries. “With the bonus, we calculated that we can expect profitability after 3 years for these large batteries for example”.
A way to avoid network overload
If domestic batteries are still not very profitable today, they nevertheless have an important advantage: that of avoiding overloading the network. Géry Cousin lives in the province of Luxembourg, in Tenneville. In his street, we no longer count the number of solar panels installed. Result: the inverter picks up and it is no longer possible to use the energy produced. “If I chose to install a domestic battery, it is for ecological reasons but also because it is an interesting system to reduce consumption peaks. If more households had a battery, the network would not be overloaded”. And this problem of network saturation is not likely to get better over the years: “A bonus system would relieve the network which will be very quickly saturated”emphasizes Matthieu Wuidar. “ÇIt is already partly and it will increase”.
Not a quick fix
However, while domestic batteries can prevent overvoltages, they are not a miracle solution for gaining energy autonomy. Domestic batteries cannot keep the energy they have stored for more than two days.
This means that in winter, when the solar panels do not produce enough, this storage is made very difficult. “Batteries can increase self-consumption by 30 to 55%”says Matthieu Wuidar. “There are still 45% where there is no solution with a battery. There are alternative means such as overheating the water in times of overproduction. But in my opinion, between summer and winter, there is no ‘there will be no technical solution in the next 5 to 10 years’.