Can a business battery earn money on FCR or aFRR?

A battery on your site can take part in Belgium's balancing market, and some owners earn extra income with it. But the income is smaller and less certain than sales pitches suggest, and it is the last job for a commercial battery, not the first. It pays most when it cuts your peak, stores your own solar power or saves you a heavier connection. Any market income comes on top, with the capacity the battery does not need for that.

You run a company, a farm or a warehouse, and you have a battery or you are thinking about one. Then the calls start. A seller says the battery "pays for itself on Elia's market". Another says now is the time, before too many batteries join and the profits fall. The savings sheet looks too good to be true.

What those calls leave out is who really uses your battery. A battery that trades for someone else is not always there when your own site needs it. It may be half empty at the Monday start-up, or full when your solar panels peak. Worse, charging hard in a cheap quarter-hour can set a new peak on your grid connection, and that peak is paid all year. The "smart" system is then smart mainly for the company that sells it.

That is why we look at the site first. On a farm in Tielt, the battery system delivers the extra power the farm needs, so a heavier grid connection was not needed. A dairy farm in Lokeren recovered its investment within 4 years because it avoided a move to medium voltage. Those are the jobs that pay a business battery back. The balancing market can add to them, but it rarely replaces them.

What is the balancing market, and why does Elia pay batteries?

The balancing market is how Elia, the Belgian transmission system operator, keeps supply and demand equal every second. The grid works at a frequency of 50 Hz. When a cloud passes over a solar park, a forecast is wrong or a power plant trips, the balance breaks and the frequency moves.

Suppliers, producers and large users work with a balance responsible party (BRP): a company that must keep its portfolio in balance every quarter of an hour. What is left over, Elia solves with reserves it buys in advance and with balancing energy it activates in real time. Whoever can quickly take power from the grid or give power back is paid for it. A battery can do both in a fraction of a second, which makes it well suited.

Elia publishes an imbalance price for every quarter-hour. When the grid is short, that price is high; when there is too much power, it is low or negative. That swing is what traders and battery owners try to earn from.

What is the difference between FCR, aFRR and mFRR?

FCR, aFRR and mFRR are three reserves that react one after the other: in seconds, in minutes and within a quarter-hour. For a battery owner, the main difference is how fast you must react and how you are paid.

FCR is bought in daily auctions for six 4-hour blocks, together with grid operators from nine European countries in the FCR Cooperation (ENTSO-E). aFRR is also traded across borders since Belgium joined the European PICASSO platform. For a business, the key figure is the 1 MW minimum. Almost no single business battery is that large, so it only enters these markets inside a pool.

How can a business battery take part in the balancing market?

A business battery takes part in one of three ways: in a pool for FCR or aFRR, through imbalance steering, or through a dynamic contract. In each case the contract is with a market party, not with the grid operator.

Whatever the route, someone else then gets a say in when your battery charges and discharges. That is fine, as long as the contract protects the capacity your site needs.

How much does a battery earn on the balancing market in 2026?

Nobody can promise you a fixed amount: balancing income depends on the quarter-hour prices, and those have become calmer. Be careful with any quote that gives a yearly figure without a range and without the costs.

• PICASSO flattened the prices. Since 26 November 2024, Belgium shares aFRR with other European countries. Inagro, the agricultural research centre in West Flanders, notes smaller price swings and shorter periods of imbalance, and "usually a fall in income" for participants.
• Elia changed its approach in 2025. Since 23 July 2025 it uses much more aFRR and less mFRR, because cross-border aFRR is cheaper. Yuso reported that imbalance-steering revenues in July 2025 were lower than in any other month that year.
• More batteries compete for the same market. FEBEG, the federation of Belgian electricity and gas companies, counted more than 150 MW of batteries in Belgium in 2025. It expects 2.3 to 2.6 GW by 2030.

Then the costs come off the gross income:

• the share for the BSP or the supplier;
• network costs on every kWh you take in and send out;
• the loss in charging and discharging;
• extra wear on the battery;
• possibly a higher peak on your connection (next section).

Can balancing trades raise your grid costs?

Yes. Grid costs follow your highest quarter-hour of offtake, and market trading tends to create exactly those peaks. Cheap moments on the imbalance market are short, so the battery charges at full power while they last.

Inagro describes a farm with normal consumption up to 90 kW. To buy as much cheap power as possible, it raised its access power to 250 kW and installed a battery. Counting only access power and peak power:

That comes to almost 19,600 euro a year more than its old situation in 2024, before any market income. On medium voltage, access power is paid per kVA and the peak per kW, every year.

On low voltage in Flanders, the capacity tariff works the same way on a smaller scale. It costs about 53.39 euro per kW per year in 2026 (average, excl. VAT). If market charging adds 40 kW to your monthly peak every month, that is about 2,136 euro a year. Only offtake counts, so discharging never raises the peak. See how to calculate the capacity tariff for your business.

What is revenue stacking, and which jobs come first for a business battery?

Revenue stacking means one battery earns from several jobs, and on a business site the order matters. Jobs that save you money every month come first; the market fills the gaps.

• Lower the quarter-hour peak. Every kW off a peak that returns every month is worth about 53 euro a year in Flanders. Read how peak shaving with a battery works.
• Store your own solar power. A self-used kWh replaces power at 20 to 25 cent; an injected kWh earns about 2 cent. See when a battery belongs with business solar panels.
• Keep critical loads running in a power cut, if the system is built for back-up. That needs charge in reserve, not an empty battery.
• Deliver more power than the connection, as in Tielt, so a heavier connection is not needed.
• Then the market: a dynamic contract, imbalance steering or a pool, with the capacity and hours that are left.

When is the balancing market worth it for your business, and when not?

It is worth a look when your battery has spare capacity at predictable hours and your connection has room. It is not worth it when the battery is already busy, or when trading would push up your peak.

A large battery built only for trading on the grid is a different business, usually a separate grid-scale project. For that route, read our overview of BESS battery storage for businesses.

What should you ask before you sign a flexibility contract?

Ask these seven questions before you let anyone trade with your battery. A serious BSP or supplier answers them in writing.

How do we size and steer a business battery?

We size the battery on your own consumption and set its control for the jobs on your site first. Market income is then an option you can add, not the reason for the size.

1. Step 1: Send us a year of quarter-hour data from your grid operator, or your latest invoices, plus your plans (solar panels, chargers, machines).
2. Step 2: If data is missing, we can measure your consumption for a short period first.
3. Step 3: Analysis and sizing: how much peak to cut, how much solar power to store, what back-up you need.
4. Step 4: Technical design, installation and commissioning.
5. Step 5: Monitoring and control. Our software offers rule-based control, a peak and off-peak programme, and Dynamic ESS, which plans charging on quarter-hour prices and weather forecasts for dynamic contracts. You follow everything in the app and the VRM portal.

Our business battery systems range from SME installations to modular systems up to 1 MW, with monitoring and control included. See how the control and monitoring software works.