SDAC (Single Day-Ahead Coupling)
SDAC is the European mechanism that clears the next-day electricity auction across coupled bidding zones in one coordinated run. NEMOs submit orders, TSOs submit network capacities and constraints, and the EUPHEMIA algorithm calculates clearing prices, matched trades, scheduled exchanges and net positions.
SDAC, Single Day-Ahead Coupling, is the European mechanism that clears the next-day electricity auction across coupled bidding zones in one coordinated run. NEMOs submit orders, TSOs submit network capacities and constraints, and the common EUPHEMIA algorithm calculates clearing prices, matched trades, scheduled exchanges and net positions.
How the auction works
Market participants submit bids and offers to their local NEMO before the day-ahead gate closure. The central matching run then solves one optimisation problem for all coupled zones, implicitly allocating cross-border capacity at the same time as energy. Power flows from cheaper bidding zones to more expensive ones until prices converge or available cross-zonal capacity is exhausted.
Estonian relevance
The EE bidding-zone day-ahead price published by Nord Pool is an SDAC result. It is the anchor for Estonian indexed retail tariffs, many PPAs, battery arbitrage strategies and balancing-market opportunity cost. Since autumn 2025, SDAC has moved from hourly to 15-minute market time units, aligning the day-ahead reference price more closely with intraday and imbalance-settlement timeframes.