Cross-zonal capacity
Cross-zonal capacity is the capability of the interconnected electricity system to accommodate power exchange between bidding zones. It is the border capacity TSOs make available to day-ahead, intraday or balancing processes after accounting for operational security limits. Scarce cross-zonal capacity is what lets neighbouring bidding-zone prices split.
Cross-zonal capacity is the capability of the interconnected electricity system to accommodate power exchange between bidding zones. In market terms, it is the border capacity made available to day-ahead, intraday or balancing processes after TSOs account for operational security limits. When cross-zonal capacity is scarce, neighbouring bidding-zone prices can separate.
How it is calculated
TSOs calculate cross-zonal capacity through capacity-calculation methodologies inside each Capacity Calculation Region. The Baltic CCR uses coordinated NTC rather than flow-based calculation. The calculated capacity is then handed into market coupling so EUPHEMIA or the SIDC systems know how much energy can move across each border in each direction.
Why prices split
If Estonia has cheap supply and Finland has expensive demand, power flows north until either prices converge or the EE-FI cross-zonal capacity is full. Once the border binds, EUPHEMIA clears different prices for EE and FI. This is the direct connection between physical interconnector availability and the spread that batteries, PPAs and FTRs care about.
Sources
CACM Regulation Article 2 · ENTSO-E: Capacity Calculation Regions