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.

To expand the graphs featured on the page, tap the double-headed arrow in the bottom right corner of the graph.


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 May 2022:  

  • Gas: 50%  
  • Wind: 21%  
  • Nuclear: 20%  
  • Interconnectors & Biomass: 3% & 3%

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.  


On 28 May 2022, the South Western GSP Group (_L) had a minimum GSP Group Take of –26MWh in Settlement Period 28. This is lowest GSP Group Take for the GSP Group since 25 April 2021 (-50MWh). 

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.


The Southern (_H) GSP Group had embedded SVA generation of 17GWh in May 2022, the highest generation total for the GSP Group in the past year. 

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.


During May, there were 164 GSPs who recorded Exported volumes, compared to 155 in April. The total export volume from these GSPs decreased by 36% to 1,187GWh in May compared to April (1,849GWh), despite the increase in number of GSPs exporting. 

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.


202 (55%) of GSPs had 0% of Settlement Periods with an exporting metered volume, i.e. all GSP metered volume in May was consumption.  

There were 11 GSPs that spent 100% of Settlement Periods exporting in May 2022, compared to 8 in April. Seven of these GSPs were in the North Scotland (_P), two in Yorkshire (_M), one in South Scotland (_N) and one in Northern (_F) GSP Groups. 


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.


South Wales (_K), Yorkshire (_M) and North Western (_G) continue to remain beyond the ADR upper threshold variation of +/- 1.5%. Investigations into these regions continue, with steps taken in South Wales (_K) continuing to reducing the ADR values in this region.  

South Eastern (_J) ADR position has stabilised, as the metered volume corrections have entered settlement in subsequent reconciliation runs, and has been above the lower threshold since November 2021 

North Scotland (_P) and London (_C) are still showing ADR values below the lower threshold. Corrections for the metering issue identified in both regions are entering settlement and should be reflected on the ADR graphs in the coming months. 

East Midlands (_B) continues to trend around the ADR upper threshold, and will be the next regions to be investigated once issues in other regions have been identified. 

Elexon will continue to update industry, and the relevant Elexon committees, on a regular basis, with feedback from committees taken into account in our investigations. 

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.


Click on the X next to any of the icons to replace them with a short-cut link to the page you are currently on or search for a specific page.

List of BSC Insights

Previous Circulars

Training videos and services

Market Entry

Charge Codes and Switch Regimes

Add New