Reduction of UMS MEM Error threshold from 2024 Quarter 1

The Unmetered Supplies (UMS) Material Error Monitoring (MEM) threshold will reduce from 10,000MWh to 7,000MWh, effective from the Quarter 1 2024 reporting window.

MEM is one of the ‘detective’ Performance Assurance Techniques that operate within the Performance

Assurance Framework. MEM is designed to:

  • Estimate the impact and materiality of a Settlement error
  • Monitor error levels over time
  • Estimate the contribution to overall market errors made by individual Parties and their Agents

The purpose of the UMS MEM reporting is to encourage UMS Operators, Suppliers and Party Agents to engage with each other to resolve Estimated Annual Consumption (EAC) mismatches, which are identified as Settlement error in Elexon’s reporting to the Performance Assurance Board (PAB).

Monitoring and reporting of UMS Metered Volumes and Metering System Identifier (MSID) counts as part of Modification P434 ‘Half Hourly Settlement for UMS Metering Systems’.

The monitoring has highlighted a recent overall reduction in Non-Half Hourly (NHH) UMS volumes. Between Q1 and Q3 2023, there was a decrease of 13,170MWh (29%) in total NHH UMS volumes.

In line with this reduction, Elexon feels it is therefore appropriate to also lower the UMS MEM Error threshold from 10,000MWh to 7,000MWh so it remains relative to the total NHH volumes. Parties that exceed the threshold are highlighted to the PAB for discussion and further investigation.

Elexon does not anticipate changing the threshold on an ongoing quarterly basis, but will continue to monitor the total NHH volumes and MSID counts in relation to UMS MEM error and P434 migration progress.


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