Frequency markets: get paid to keep the grid at 50 Hz.

Why the grid pays for flexibility

Electricity production and consumption have to match every second. The balance shows up in grid frequency: when real output drifts from forecast, frequency moves off 50 Hz, and the transmission system operator has to pull it back. It does that by buying corrective power on the frequency-reserve markets — paying assets to feed the grid when there's a shortage and to absorb power when there's a surplus.

In Estonia that operator is Elering. Any asset that can move quickly — a battery, a controllable industrial load, a solar or wind park with active control — gets paid for standing ready, and paid again each time it is called.

Three products, three speeds

Reserves are split by how fast they respond. FCR is automatic and fully delivered within 30 seconds — the grid's first reflex. aFRR is automatic too, fully activated within about five minutes through PICASSO. mFRR is activated manually, with full delivery inside 12.5 minutes through MARI. For grid-scale batteries in Estonia, mFRR is currently the largest balancing-capacity revenue stream.

These reserves sit on top of the energy markets — the day-ahead auction and the intraday market — where the electricity itself is traded. Capacity for all three reserve products is procured together, each morning, for next-day delivery.

One Baltic balancing market

Estonia synchronised with Continental Europe in February 2025. Since then the Baltic states buy reserves through a joint market — the Baltic Balancing Capacity Market — run by Elering, AST and Litgrid, which co-optimises FCR, aFRR and mFRR across the three zones. One pool, cleared once a day.

Frequency markets, answered plainly

How do I join the frequency markets?

Get a quote, sign the standard balancing-services agreement, and let Volton run Elering prequalification, typically under seven days. You don't become a BSP yourself. You join Volton's Reserve Providing Group, which already meets Elering's 1 MW minimum. After connection your asset bids the next day and earns from the first cleared interval. There is no upfront fee.

How much can I earn on the frequency markets?

A 50 kWh home battery typically earns 40 to 120 euros per month from frequency reserves, depending on availability hours and capacity clearing prices. Industrial assets of 1 MW or more earn 100 to 900 euros per MW per day across capacity and activation revenue, depending on the product mix and how often the system calls them. Volton publishes the cleared mFRR and aFRR capacity prices weekly, so you can check what you would have earned before signing.

Who can participate?

Any grid-connected asset that can change its output or consumption quickly: batteries, controllable industrial loads, heat pumps, EV chargers, solar parks and wind farms with active control. Standalone assets need at least 1 MW of qualifying capacity, so smaller assets join through an aggregator. Volton pools dozens of sites into Reserve Providing Groups that clear Elering's thresholds, so a 50 kW home battery or a 200 kW industrial load can earn without prequalifying on its own.

How are providers paid?

Two streams. The capacity payment is a fixed rate for being available, paid for every hour your asset is qualified, even if the system never calls it. The energy payment is paid each time Elering activates your asset, at the price set in the activation auction. Combined, frequency reserves can earn 100 to 900 euros per MW per day depending on the product and how often the asset is activated. Volton invoices the markets monthly, deducts a transparent share, and pays the rest into your account.