Line Loss Factor

Line Loss Factors (LLFs) adjust metered consumption to account for technical losses in the distribution network - electricity converted to heat as it flows through cables and transformers. This is the physics of electricity transmission that the LLFC (Line Loss Factor Class) code captures.

How LLFs work:

• Expressed as a percentage above metered units
• Higher for lower voltage connections (more transformation losses)
• Varies by time of year (seasonal factors)
• Different for import vs export
• Set by DNOs based on network modelling
• Published by Elexon (the BSC agent) as Industry Standing Data (ISD)
• Elexon-published values are the authoritative source used in settlement

Example: An LLF of 1.08 means for every 100 kWh metered at your premises, 108 kWh is deemed to have been consumed at the GSP (Grid Supply Point). The extra 8% accounts for energy lost in the cables and transformers between the GSP and your meter.

Why voltage matters:

• High Voltage (HV) connections: Lower losses (~2-4%)
• LV Sub connections: Medium losses (~5-7%)
• Low Voltage (LV) connections: Higher losses (~7-10%)

This is why large industrial sites often have their own substations with HV connections - the savings on line losses can be substantial.