TLAFs - Transmission Loss Adjustment Factors

Transmission Loss Adjustment Factors are how we allocate transmission losses to the generators.

What are TLAFs?

When electricity is being transported through networks, not all of the power is transferred. 

These losses can happen on both the transmission and distribution networks. Higher voltages generally reduce losses.

To ensure that the wholesale market is settled, we allocate the transmission losses to generators. 

These calculations are called Transmission Loss Adjustment Factors (TLAFs). 

They are calculated by EirGrid and SONI and approved by the Regulatory Authorities (RAs) annually.


Who TLAFs Apply To

Some generators are responsible for proportionally more transmission losses than others. It depends on their point of connection to the grid. For this reason, TLAFs are site specific.

The following parties that participate in the SEM, known as market participants, are subject to TLAFs:

  • Generators connected to the transmission network
  • Generators connected to the distribution network
  • Interconnectors
  • Suppliers (TLAFs for Supplier Units are set equal to 1.0)


Approved TLAFs