Cross-Zonal Capacity within Balancing Timeframe (CZCBT)
Cross-Zonal Capacity within Balancing Timeframe (CZCBT) is the share of cross-border transmission capacity that two connected TSOs reserve for the exchange of balancing energy after the day-ahead and intraday markets have used what they need. CZCBT is what makes MARI and PICASSO actually able to clear mFRR and aFRR across borders; methodology set by EBGL Articles 38–39. Without CZCBT, the EU activation platforms would clear inside each LFC area in isolation.
Cross-Zonal Capacity within Balancing Timeframe (CZCBT) is the share of cross-border transmission capacity that two connected TSOs reserve for the exchange of balancing energy after the day-ahead and intraday markets have already used what they need. CZCBT is what makes MARI and PICASSO actually able to exchange mFRR and aFRR across borders — without it, balancing platforms would clear inside each LFC area in isolation.
Where CZCBT comes from
Total cross-zonal capacity on a border is calculated by the regional Capacity Calculation Region (in the Baltics: Baltic CCR). That capacity is allocated in sequence: long-term auctions first (JAO), then day-ahead SDAC, then intraday SIDC, and whatever residual capacity remains in the balancing timeframe becomes CZCBT for MARI and PICASSO. EBGL Articles 38 and 39 set the methodology for calculating the residual capacity and the algorithm for sharing it across the activation platforms.
Why it matters
When CZCBT is plentiful, the EU activation platforms clear at one common cross-border marginal price across the connected area — the cheapest balancing bid in any country sets the price for everyone. When CZCBT binds (interconnector saturated), the area splits into separate price zones; one country can clear at the platform price cap while a neighbour clears low. In the Baltics, CZCBT-binding events are visible as price divergence between Estonia, Latvia and Lithuania on the same MTU.
Where you see this in Baltic data
The Baltic Transparency Dashboard publishes a dedicated "Cross-Zonal Capacities" report showing CZCBT per border per MTU, together with the resulting cross-border marginal price (CBMP). For BSPs and BRPs in Estonia, CZCBT is the variable that explains why the realised mFRR price sometimes diverges sharply from the headline MARI marginal price published by ENTSO-E.
Sources
EBGL Articles 38–39 (cross-zonal capacity for balancing) · BTD: Cross-Zonal Capacities report · ACER: Balancing market rules
Frequently asked
- What is CZCBT?
- Cross-Zonal Capacity within Balancing Timeframe (CZCBT) is the part of cross-border transmission capacity that two TSOs make available to MARI and PICASSO for cross-border exchange of balancing energy, after long-term, day-ahead and intraday markets have already used the rest. It is what lets the EU activation platforms clear at one common cross-border marginal price across connected areas.
- How is CZCBT calculated?
- EBGL Articles 38 and 39 set the methodology. The Capacity Calculation Region (in the Baltics: Baltic CCR) calculates total cross-zonal capacity on each border. That capacity is then sequentially allocated to long-term auctions (JAO), day-ahead SDAC, intraday SIDC, and whatever residual remains in the balancing timeframe becomes CZCBT for MARI / PICASSO use.
- Why does CZCBT matter for prices?
- When CZCBT is plentiful, the activation platforms clear at one common cross-border marginal price (CBMP) across the connected area — the cheapest balancing bid in any country sets the price for everyone. When CZCBT binds, the area splits and each segment clears at its own local marginal price, often diverging dramatically. This is why Baltic mFRR prices sometimes diverge sharply between Estonia, Latvia and Lithuania on the same MTU.
- Where can I see CZCBT data for the Baltics?
- The Baltic Transparency Dashboard publishes a dedicated "Cross-Zonal Capacities" report showing CZCBT per border per Market Time Unit, alongside the resulting cross-border marginal price (CBMP) and the actual netted volumes flowing through MARI and PICASSO.