Bidding zone
A bidding zone (pakkumispiirkond) is the largest geographic area within which market participants can exchange energy without the cross-border-capacity constraint becoming a price boundary. Estonia is the EE bidding zone — a single nationwide day-ahead clearing price. Cross-border allocation with FI, LV and SE4 is implicit, handled by the SDAC algorithm clearing all coupled zones simultaneously.
A bidding zone (pakkumispiirkond) is the largest geographic area within which market participants can exchange energy without the cross-border-capacity constraint becoming a price boundary. Inside a single zone the day-ahead clearing price is uniform; between zones, prices diverge whenever the interconnector cannot transport enough power from the cheaper to the more expensive side. The construct is defined in CACM Regulation (EU) 2015/1222 Article 2.
Estonia is one zone
Estonia is the EE bidding zone — a single nationwide day-ahead clearing price for every hour. The neighbouring zones are FI, LV, SE4 (south-Sweden) and a synchronous link to the Continental European set since 9 February 2025. Cross-border allocation is implicit: the SDAC algorithm clears all coupled zones simultaneously and capacity flows from the cheap zone to the expensive one until either prices converge or the interconnector hits its limit.
When EE prices diverge from FI
The Estonia–Finland interconnection (Estlink 1 + Estlink 2 = 1 000 MW HVDC, when both operational) is the most economically active bidding-zone boundary for Estonia. When EE wind production peaks while FI demand is moderate, Estonia exports and prices converge. When Estlink 2 is out for maintenance or damaged (e.g., the December 2024 Eagle S incident, repaired by June 2025) the spread widens, sometimes to several hundred euros per MWh. This is the spread that makes BESS arbitrage profitable in Estonia.