Transmission Loss Adjustment Factors
Transmission Loss Adjustment Factors
Losses are incurred on the Transmission System as electricity is transported from generators to the transmission / distribution interface. In settlement, the transmission losses are allocated to generators (including generators embedded in the distribution system), using Transmission Loss Adjustment Factors (TLAFs). Some generators are responsible for proportionally more transmission losses than others, depending on their point of connection to the grid. For this reason, TLAFs are site specific.
The following parties are subject to transmission losses:
- Generators (including green) connected to the transmission network .
- Distribution connected (embedded) generators (including green) connected after 19 February 2000.
The following principles apply to the treatment of transmission loss factors:
- Loss factors are calculated by the TSO and approved by the Commission for Energy Regulation (CER) on an annual basis.
- The TSO derives TLAFs using marginal loss factors.
The TSO scales the marginal loss factors to ensure that throughout the year only average losses are recovered. These final values, after scaling, are the TLAFs. Marginal loss factors are scaled to derive the TLAFs so that the allocations they produce will equal the predicted average transmission losses.
| Transmission Loss Adjustment Factors - Background Information | Effective Date |
|---|---|
| Mid-year Re-calculation Policy - Transmission Loss Factors | 12-01-05 |
| Comments Received on Derivation - Transmission Loss Factors | 31-05-03 |
| Derivation Review - Transmission Loss Factors | 16-04-03 |
| Treatment of Transmission Losses | 05-04-00 |
| SEM Transmission Loss Adjustment Factors – 2010 | Effective Date |
|---|---|
| 2010 SEM ROI Market Participant Transmission Loss Adjustment Factors – PDF (Please Note: PDF document is the official publication of these values) | 24-06-10 |
| 2010 SEM ROI Market Participant Transmission Loss Adjustment Factors – XLS | 24-06-10 |
| 2010 SEM ROI Transmission Node Indicative Transmission Loss Adjustment Factors | 22-12-08 |
| SEM Transmission Loss Adjustment Factors – 2009 | Effective Date |
|---|---|
| 2009 SEM ROI Market Participant Transmission Loss Adjustment Factors – PDF (Please Note: PDF document is the official publication of these values) | 10-12-09 |
| 2009 SEM ROI Market Participant Transmission Loss Adjustment Factors – XLS | 10-12-09 |
| 2009 SEM ROI Transmission Node Indicative Transmission Loss Adjustment Factors | 19-12-08 |
Estimated Transmission Loss Adjustment Factors - 2011
Transmission Loss Adjustment Factors (TLAFs) are calculated annually by EirGrid and SONI. They are applied to all generators participating in the All-Island Single Electricity Market (SEM).
Following discussion with industry participants, EirGrid undertook to conduct a study to calculate indicative TLAF data for a year further into the future, separate from the annual calculation but using the same methodology. The year chosen was 2011.
Please note that the results are indicative only and based on a number of assumptions as detailed in the document below.
2011 Indicative TLAFs - PDF
2011 Indicative TLAF Assumptions
Archive TLAF Documentation
- SEM Transmission Loss Adjustment Factors
- Transmission Loss Adjustment Factors – (Pre SEM)