Formal title: Electricity Balancing Significant Code Review Developments

Current Status

Initial Written Assessment
Assessment Procedure
Report Phase
With Authority
Awaiting Implementation


P305 has been raised to progress the outcomes of the Electricity Balancing Significant Code Review (EBSCR), and proposes to implement the EBSCR conclusions ahead of winter 2015/16, which consists of the following areas:

  • A reduction in the Price Average Reference (PAR) and Replacement PAR (RPAR) values to better reflect the marginal cost of balancing energy for a given Settlement Period.
  • A single imbalance price using the existing Main Price calculation.
  • Introduction of a Reserve Scarcity Price (RSP) function for Short Term Operating Reserve (STOR) actions to better reflect the prevailing scarcity in the market at the time of their use.
  • Introduction of Demand Control actions into the imbalance price, priced at the Value of Lost Load (VoLL), and an imbalance volume correction process to amend participants’ positions to account for such actions.

12 Month Post-implementation Review of P305

Held in March 2017, this 30-minute webinar increases industry’s understanding of the BSC Modification P305 following a 12-month post implementation review. The webinar also highlighted the main trends seen in our analysis and how our findings compared to previous years. It also covers System Length, System Prices and Balancing Behaviour.

An Overview of the Post-implementation Review of P305

In July 2016, we held two 30-minute webinars to support industry’s understanding of BSC Modification P305.

The second 30-minute webinar ‘An overview of the post-implementation review of P305’ discussed the key findings of the new Post implementation review of Modification P305.

An Introduction to P305

In July 2016, we held two 30-minute webinars to support industry’s understanding of BSC Modification P305.

The first 30-minute webinar ‘An introduction to P305’ provided an overview of the changes to the price calculation.


National Grid raised P305 on 30 May 2014. The Panel agreed to submit P305 to an Assessment Procedure, during which it was issued for industry Impact Assessment and the Workgroup’s Assessment Procedure Consultation. The Workgroup recommended that the Alternative Modification should be approved, and its Assessment Report was presented to the Panel on 12 February 2015.

The Panel initially recommended that both the Proposed and Alternative Modifications should be rejected, and issued P305 for its Report Phase Consultation. The Panel made its final recommendation that both the Proposed and Alternative Modifications should be rejected at its meeting on 12 March 2015.

The Authority approved the P305 Proposed Modification on 2 April 2015 for implementation on 5 November 2015 as part of the November 2015 Release.

Code Subsidiary Document changes

The changes to Code Subsidiary Documents impacted by P305 can be found on the November 2015 Release page.

Historic analysis output data

The output data from the Workgroup’s historical analysis is available to download from the Elexon Portal (a free login account is required to access this page).

P305 Post Implementation Review

A 12 month review of P305 can be found on the Operations Reports page.

Ofgem as the Authority’s post implementation review can be found here.


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