A battery trading in Spain navigates a sequence of markets. Each gate opens and closes in a fixed order between day-ahead and real-time delivery. Two operators run the sequence.

OMIE (Operador del Mercado Ibérico de Energía) runs the wholesale markets. Red Eléctrica de España (REE), the Spanish transmission system operator (TSO), layers the grid-stability markets (servicios de ajuste) on top.

An optimiser bids a battery sequentially, co-optimising across OMIE's wholesale markets and REE's ancillary services. Revenues can stack across day-ahead, technical restrictions, aFRR (automatic Frequency Restoration Reserve) capacity, intraday auctions, the continuous intraday market, and real-time energy activation.

Every commitment narrows the options for later gates. The order in which a battery clears matters as much as the price it achieves in any one market.

How does the day-ahead market anchor the Spanish stack?

The first market a battery operator considers is the day-ahead market (DA). OMIE runs it as part of the Single Day-Ahead Coupling (SDAC), the European auction that clears most of the continental wholesale market in a single run.

Order books open on the morning of D-1. Gate Closure Time (GCT) is 12:00 Central European Time (CET). Final results are published at approximately 12:57. Since 1 October 2025, the granularity has changed to 15-minute intervals, resulting in 96 periods per day, up from 24 hourly periods.