Material Error Monitoring


Material Error Monitoring is designed to: Estimate the impact and materiality of a Settlement Error; Monitor error levels over time; and Estimate the contribution to overall market errors made by individual Parties and their Agents. The process also helps us rank customer performance in the market and identify operational issues.

How it relates to you

Material Error Monitoring provides assurance to Panel committees and other market participants that a Performance Assurance Party’s contribution to the error is quantified and the impact of such errors is established.

This technique complements the BSC Audit, Technical Assurance, Error and Failure Resolution and Trading Disputes processes.

The PAB has a set of reporting requirements used to monitor materiality.

How does the process work?

We use the Material Error Monitoring process to analyse settlement data and supplementary data to estimate and track identified material errors.

We can model and communicate the impact of identified settlement errors to the Performance Assurance Board and/or Trading Disputes Committee to help them make decisions.

It also enables us to provide estimated error contribution to customers confidentially so they can monitor their progress in resolving errors.

What are the big issues at the moment?

Issues we’re currently monitoring include:

  • Erroneous Large Estimated Annual Consumption (EAC)/Annualised Advances (AAs)
  • Unmetered Supplies (UMS)
  • Incorrect Energisation Status
  • Additional Information

Erroneous Large EAC/AAs

Discover full details of Erroneous Large EAC/AAs and how the process works by reading the relevant guidance note



A number of workshops on Erroneous large EAC/AA were held at ELEXON’s offices during 2011-2013.

Incorrect NHH Energisation Status & Unmetered Supplies

Metering System Energisation Status

Metering System Energisation Status is used by Non-Half Hourly Data Aggregators (NHHDAs) to determine whether consumption for a Metering System is included in data aggregation.

If the Energisation Status in the Supplier Meter Registration Service (SMRS) does not match the actual physical status, this can result in a Settlement error. Settlement Risk SR0026 relates to incorrect Energisation Status.


Unmetered Supplies

ELEXON monitors the issue of erroneous values of Unmetered Supplies in the Non Half Hourly (NHH)
market. The monitoring involves comparing UMS data from Unmetered Supplies Operators (UMSOs)
and Non Half Hourly Data Aggregators (NHHDAs) on a particular Settlement Date following the SF


The monitoring takes place quarterly and the dates used can be found in the UMS Monitoring

Performance Assurance Framework

Material Error Monitoring is a detective technique in Elexon’s Performance Assurance Framework.


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