Settlement error identified in GSP Group _G

Elexon has identified an error in Settlement volumes attributed to a windfarm located in GSP Group _G.

How this may impact you

Parties that are active in GSP Group _G will either receive sums or pay sums during the period where Settlement reconciliations are taking place to correct the volumes for the affected Settlement Days.

Identifying the cause of the error

Maintaining the accuracy of Settlement is of upmost importance to Elexon, and we continually review Settlement data to highlight and subsequently investigate anomalies, which can indicate errors.

Following the identification of an anomaly in Metered Volumes associated with a windfarm in GSP Group _G, an investigation was opened by Elexon in November 2023 to confirm whether the Metered Volumes were genuine.

After discussions with the Registrant, it was confirmed that estimated Metered Volumes had been submitted into Settlement between November 2022 and December 2023. The estimated Metered Volumes that were submitted were not a true reflection of the site’s volumes.

The site had a Meter Exchange in November 2022 as a result of a fault on the old Metering System. The new Metering System was not capable of being dialled by the Central Data Collection Agent (CDCA), which resulted in estimated data being entered into Settlement.

Due to the complex nature of the Metering System, the channels differ on the Meter Technical Details (MTDs) to those at the physical Meter. When the data was initially corrected in Settlement, the channels were reversed and, subsequently, data was entered into Settlement incorrectly, causing a further error. This has since been rectified and will be corrected through later Settlement Runs. All materiality calculations have taken this further error into consideration.

Correction of the error volumes

Settlement will be assessed corrected in two stages in line with the Settlement reconciliation process:

  • Estimated data that will be corrected in normal Settlement Runs between 18 November 2022 and present day by replacing the estimated data with actual data.
  • The period between 4 April 2022 and 17 November 2022, which cannot be corrected via normal Settlement Runs and may be correctable via a Trading Dispute which, if upheld, would be updated in the Post Final Settlement (DF) Run.

This latter period is currently being investigated to determine if Settlement needs to be amended and if a Trading Dispute would be valid. This investigation will determine the effect on Settlement of the Meter fault that was in existence prior to the Meter exchange on 17 November 2022.


Elexon has calculated the total approximate materiality of the fluid period correction to be £7.1M. Elexon is contacting BSC Parties individually that will see the greatest impact of the correction.

Further updates will be provided on the Trading Disputes investigation as it progresses.


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