How we’re helping to spot GSP metering errors sooner

In the past eight years, we have identified five Grid Supply Point (GSP) Metering errors, equal to around 1.4% of the total number of GSP Meters. These errors have caused energy to be recorded incorrectly. As any unaccounted energy is allocated to BSC Parties through GSP Group Correction and Transmission Losses, such metering errors can present a large impact on the allocation of energy and therefore the accuracy of Trading Charges to BSC Parties.

We are publishing a beta version of our GSP change-point detection model to gather feedback from participants and help us identify other areas where central analytics and reporting could support industry in mitigating risks to Settlement.

Recent example of the issue

The most recent of such GSP metering errors were identified at two sites in GSP Groups _C and _J which are described in BSC Panel paper 326/07 and between them impacted Trading Charges by an estimated £117.5m.

We have also published an update today (16 May) on the errors at the two sites.

Elexon recognises the significant impact these errors have on BSC Parties and understands the concerns raised through the engagement about the impact that errors of this size have on the operation of companies.

How Elexon can help

In our capacity as the Performance Assurance Administrator, Elexon continues to seek new and innovate ways to manage Settlement Risks such as those associated with GSP Metering.

Whilst the assurance framework’s main goal is to prevent such issues from occurring in the first instance, should they occur it is essential that they are detected quickly to minimise the impact on BSC Parties.

This will become even more important as we transition to Market-wide Half Hourly Settlement where Settlement timescales are due to reduce from 14 to around four months.

As part of our assurance work, we have developed a machine learning based model to detect and alert unusual consumption patterns or step changes (referred to as “change-points”) at individual GSP Metering Systems. These change-points may equate to the introduction of metering issues as seen in recent years.

Registrants are responsible for their metering equipment

Please note that this monitoring does not seek to detract from participants meeting their obligations under the BSC, such as the obligations on CVA Registrants to ensure Metering Equipment is kept in good working order, repair and condition such that energy volumes are recorded correctly.

The Performance Assurance Board has and will consider further preventative and remedial actions to stop such metering errors occurring in future. The central monitoring Elexon performs is the last line of defence in detecting Settlement Errors and as such we want to ensure that it is as robust as possible.

The following dashboards provide the presentation layer from this analytical model.

Annual Demand Ratio

The below dashboard provides a view of Annual Demand Ratio (ADR) per GSP Group over the past 5 years. ADR provides a high level of understanding of any significant under or over accounting of energy in Settlement.

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 Supplier Volume Allocation (SVA), the under-accounting of export energy in SVA or under-accounting of 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.

Graph showing Annual Demand Ratio by GSP Group

How to use the dashboard:
Please note that we would encourage you to click the toggle button to show a view of ADR by Settlement Run. This demonstrates a consistent trend of ADR tracking lower at earlier runs.

We attribute this to the large volumes of estimation in the NHH market at earlier runs which can be as much as 85% of NHH energy at the Initial Settlement (SF) Run. We understand that NHH estimation will, on average, tend to overstate consumption which drives ADR downwards.

GSP change-point detection

The dashboard below provides details of the change-points identified at GSPs in all 14 regions over the last 3 years. We see about three GSP change-points being flagged on average each month.

However, we saw this spike to 26 in the month of March 2020 as we saw demand drop across the UK as a result of the national lockdown.

Graph relating to Change Point Detection for GSP Metered Volume


How to use the dashboard:
Click on an individual GSP in the table above and the “click here for details” button that appears to drilldown into that GSP.

The table below outlines how the change-point detection models performs against historical GSP metering issues. Note that the GSP metering error in _J was not detected by the model as it was introduced at initial installation, i.e. there was no change-point to detect. A different approach would be required to attempt to flag up such issues in future.

GSP Group

GSP metering error detected

Months impacted

Estimated materiality

Change-point model detection





6 days





14 days





46 days





Not detected*





21 days

About the data

The data on which this is based (CDCA-I030) is publicly available via the Open Settlement Data section of our website.

Please note that this is currently a beta version and therefore is for information purposes only.

Sending your feedback

Please review this data and send us your feedback to help us develop the service further to meet your needs.

For example:

  • Would you like this curated view of the data to be made available to you on demand through the Elexon Kinnect Customer Solution or Insights Solution?
  • Are there any other areas where central monitoring could help mitigate risks to Settlement in a similar way to this example?
  • Would you like data alert notifications when we become aware of potential Settlement data quality issues? For example, when ADR is tracking outside of tolerances within a GSP Group?

Please get in touch with us on the above or any other aspects of this article at [email protected].


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