Balancing surveillance

Each balancing period is compared with its own trailing history, in both directions. What the ladder is made of differs by zone, and so does what a finding may say. In Belgium the operator publishes the ranked offers themselves, and a price step can be identified while its owner cannot. In Great Britain each unit publishes its own prices and physical position, so the ladder is reconstructed here and carries that assumption, but the units are named and the price-setting actions are published with the publisher's own weights.

In Great Britain a further 12% of periods have their price set outside the mechanism altogether, by services bought under their own contracts. Those are named (service, party and asset) and reported rather than screened, because a contracted service has no ladder to be compared with. Frequency response, meaning Dynamic Containment, Moderation and Regulation, is a separate market again and is not covered for any zone.

Supporting views show settlement components, day-ahead exposure and reserve procurement. They provide context; they do not apply surveillance thresholds. They cover Belgium: the GB regulatory feed publishes no equivalent of the imbalance-price components, the activation split or the reserve tenders they are built from.

• Settlement replay
• Day-ahead vs imbalance
• Capacity auction

Belgium and Great Britain. Belgian bids are readable from 2024-05-22 within the publisher's rolling two-year window. GB periods are measured once the publisher's next settlement run has revised them, which is the morning after delivery, and that run is not the final reconciliation. Settlement can be revised. Constraints, outages and hedges remain possible explanations for a finding.