Each year Elexon publishes a Network Mapping Statement which is a technical document that they use to help calculate Transmission Loss Factors (TLFs).
Why Transmission Loss Factors are important
Some electricity is lost as heat as it travels through networks from power stations to homes and businesses. These losses vary depending on location. Elexon's Network Mapping Statement details how the transmission network connects the Electricity Nodes, Grid Supply Points, Interconnectors and Balancing Mechanism Units to one another. This is one of the data inputs used by the Transmission Loss Factor Agent (an external company which supports Elexon) to calculate the TLFs.
TLFs reflect how electricity losses vary across the 14 zones of the transmission networks. They help ensure that generators and consumers are charged or credited fairly for the actual amounts of electricity that are produced or consumed, once losses are factored in. They play an important role in ensuring that the cost of these losses is accurately allocated to where electricity is consumed and generated.
Elexon’s role in setting Transmission Loss Factors
Elexon works with the Transmission Loss Factor Agent to create and validate TLFs, using input data from both Elexon and the National Energy System Operator.
Where to view the Network Mapping Statement
Elexon have now published the latest Reference Network Mapping Statement for 2024-2025. It forms a key input into the calculation of TLFs to be used in Balancing and Settlement Code (BSC) year 2026-2027.
You will need to create an Elexon Portal account to view it. Creating one is a simple process. Just click the ‘Register Now’ button at the top right of the screen.
Which companies is the Network Mapping Statement relevant to?
Elexon encourages all Suppliers, network companies, and large consumers to read the Network Mapping Statement as TLFs may influence how much BSC Parties are paid (or must pay) through the imbalance Settlement process that Elexon manages.
TLFs will impact the Transmission Loss Multipliers applied to metered volumes, to reflect the location of Balancing Mechanism Units , and so may impact your imbalance calculations. Transmission Loss Multipliers are applied to Balancing Mechanism Units in a Settlement Period to adjust for Transmission Losses.