System Prices Analysis Report

The System Prices Analysis Report (SPAR) provides a monthly update on price calculations. It is published by the ELEXON Market Analysis Team to the Imbalance Settlement Group (ISG) and on the ELEXON Website ahead of the monthly ISG meeting.

This report provides data and analysis specific to System Prices and the Balancing Mechanism. It demonstrates out-turn prices and the data used to derive the prices. The data is a combination of II and SF Settlement Runs.

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Highlights in the latest report

This month’s SPAR also contains an appendix on tagging of energy balancing volumes.

System Prices and Length

In this report, we distinguish between a ‘long’ and a ‘short’ market when analysing System Prices because the price calculation differs between two scenarios.

When the market is long, System Prices are based predominantly on the System Operator’s ‘sell’ actions such as accepted Bids.

When the market is short, System Prices are based predominantly on the System Operator’s ‘buy’ actions.


In this section, we consider a number of different parameters on the price. We consider:

  • The impact of Flagging balancing actions
  • The impact of NIV Tagging
  • The impact of PAR Tagging
  • The impact of the Replacement Price
  • How these mechanisms affect which balancing actions feed into the price

Balancing Services

This section covers the balancing services that the System Operator (SO) takes outside the Balancing Mechanism that can affect the price.

P305 – Specific Analysis

This section compares live prices with two different pricing scenarios. First we consider what prices would look like with the pre-P305 price calculation to highlight the impact of P305. Before the implementation of P305, the price calculation had:

  • A PAR of 500MWh, and an RPAR of 100MWh
  • No non-BM STOR volumes or prices included in the price stack
  • No RSVP, and instead a Buy Price Adjuster (BPA) that recovers STOR availability fees
  • No Demand Control, Demand Side Balancing Reserve (DSBR), or Supplementary Balancing Reserve (SBR) actions priced at VoLL

We also consider the November 2018 Scenario, which captures the effect of changes to the Imbalance Price parameters that are due to come in on 1 November 2018. These are:

  • A reduction in the PAR value to 1MWh (RPAR will remain at 1MWh)
  • The introduction of a ‘dynamic’ LoLP function
  • An increase in the VoLL to £6,000MWh, which will apply to all instances of VoLL in arrangements, including the RSVP function

Appendix 1 – Increase in the Replacement Price Setting the Imbalance Price

This month our Business Intelligence Analyst, Emma Tribe, looks at how often the Replacement Price is calculated using the Market Index Price (MIP). Where there are no priced actions, the Replacement Price sets the Imbalance Price. This analysis has also been presented to the ISG in an information paper.

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