Release guidance for P350: Introduction of a seasonal Zonal Transmission Losses scheme

This page sets out the stages Modification P350 will go through ahead of implementation into operational activity. The CMA is mandating, through secondary legislation and licence changes, an Implementation Date of 1 April 2018.

Current status

  • Implemented on 1 April 2018.

How it relates to you

Key changes to the processes and obligations within the electricity industry will impact the following:

  • Generators
  • Suppliers
  • Distribution System Operators (DSOs)
  • Transmission Company (National Grid)
  • Balancing Mechanism Reporting Agent (BMRA)
  • Central Data Collection Agent (CDCA)
  • Central Registration Agent (CRA)
  • Settlement Administration Agent (SAA)
  • BSC Auditor

About the Modification

The Competition and Markets Authority (CMA) Energy Market Investigation concluded that the absence of locational pricing for transmission losses has an adverse effect on competition.

In line with the CMA’s determination, P350 will introduce a Transmission Loss Factor for each TLF Zone (which will align with the existing Grid Supply Point (GSP) Groups) for each BSC Season in order to allocate transmission losses on a geographical basis.

National Grid raised P350 ‘Introduction of a seasonal Zonal Transmission Losses scheme’ on 4 July 2016. The Draft Modification Report for P350 was presented to the Panel on 9 February 2017, who unanimously recommended that P350 be approved.

On 24 March 2017, Ofgem approved P350 for implementation on 1 April 2018.


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