Generation and Demand data from the Trading Operations Report


The page below details highlighted Generation and Demand data from the previous month. This data is acquired from BSC Agents and inputted to the Trading Operation Monitoring Analysis System (TOMAS) database.

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Sum of CVA Generation by fuel type per settlement date

BM Units that are registered in the Central Volume Allocation arrangements rather than through the Supplier Volume Allocation Arrangements have their metered data collected centrally by the Central Data Collection Agent. A single fuel type is assigned to each BM Unit and the sum of metered volume by fuel type is displayed by Settlement Day.


CVA generation in October 2023 

  • Gas: 30%
  • Nuclear: 16%
  • Wind: 29%
  • Biomass: 6%

Minimum GSP Group Take based on SF run

The aim of the charts is to provide timely notification of any GSP Group that could become a net exporting GSP Group. The concern is that the underlying rules in the BSC implicitly assume that GSP Groups will import energy. Any deviation from this assumption results in the rules becoming unstable.

This chart provides a plot of the minimum value of GSP Group Take, (i.e. consumption) at the (Initial Settlement) SF run for each of the GSP Groups in each Settlement Day over the last 3 months. A negative GSP Group Take means the GSP Group is a net exporter.  


There are no major highlights. 

Maximum GSP Group metered volume supplied by SVA registered embedded generation for each GSP Group

This chart shows the daily sum of the SVA Registered Embedded Generation volume for each GSP Group for the day when that GSP experienced the highest volume of Embedded Generation during that month.


There are no major highlights.   

Imports and Exports by GSP Group

Within each GSP Group, there will be multiple connections between the Transmission and Distribution Systems is known as a Grid Supply Point (GSP). 

This graph displays the net Import or Export metered volume of each of these GSPs for each Settlement Period. The volumes are taken from the SF Settlement Run of the reporting month.


There are no major highlights. 

Percentage of Settlement Periods of GSP Export

Similar to the previous graph, this visualisation displays the percentage of Settlement Periods in the month the GSPs were exporting metered volume.


There are no major highlights. 


Annual Demand Ratio Values based on Settlement Run Type R2 or later

The chart below shows the ADR values for each GSP Group on a daily basis. ADR values have been calculated for the year ending on the dates indicated. To achieve the best trade-off between up to date information and accuracy the chart is based on Second Reconciliation (R2) Settlement Run data or from later Settlement Runs if these are available. Trends in the pattern of ADR may indicate issues with metering data within the GSP Groups.


GSP Group _B and _F have both moved below the upper threshold. GSP Group _P has fallen below the lower threshold, but this is likely to be caused by the known wind farm issue in this region (see GSP GCF section for more details).

ADRs are beginning to become more volatile, with several GSP Groups trending near or above the upper threshold. GSP Groups _G and _M remain above the upper tolerance and continues to slowly rise; so far, the cause of this higher-than-expected ADR for this GSP Group has yet to be identified.

Elexon are discussing how best to approach these investigations, with cross team discussions taking place.

About Annual Demand Ratio

Annual Demand Ratio provides a high-level understanding of the overall performance of the Non Half Hourly (NHH) Supplier Volume Allocation (SVA) market and identifies any significant under-/over-accounting of energy. Whilst the theoretical ‘ideal’ value of ADR is 1, variations of +/- 1.5% are to be expected due to inaccuracies in line loss estimates and a small usage of estimates at Final Reconciliation (RF) run. Values of less than 1 may result from the over-accounting of import energy in SVA, the under-accounting of export energy in SVA or under-accounting of Grid Supply Point (GSP) metering. Values of greater than 1 may result from the under-accounting of import energy in SVA, the over-accounting of export energy in SVA or over-accounting of GSP metering.


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