
A 10 kWh home battery earns ~€730/year from spot arbitrage alone. Stacked with aggregated frequency-reserve revenue (only available via a BSP), the same hardware can clear above 10% IRR.

Manual Frequency Restoration Reserve is activated by a human operator, with full delivery in 12.5 minutes. In Estonia, it is currently the most lucrative balancing market for batteries.

Automatic Frequency Restoration Reserve activates in ~30 seconds via TSO control signal, follows it on a 4-second cycle, and pulls the grid back to 50 Hz. PICASSO is quietly transforming the market.

Frequency Containment Reserve activates within 30 seconds of a frequency deviation, fully automatic, no TSO signal. Batteries dominate it. It is what made grid-scale storage economically viable.

A real-world case study of the economics of a 1 MW / 2 MWh BESS project on the mFRR market in Estonia — capex, monthly costs, revenue and 15-month payback.

From 2026 Estonia will calculate grid fees and renewable charges on net consumption only — a major step that can save a 100 MW BESS over €3M per year.