P229 Introduction of a seasonal Zonal Transmission Losses scheme

Formal title: Introduction of a seasonal Zonal Transmission Losses scheme

Current Status

Initial Written Assessment
Assessment Procedure
Report Phase
With Authority


P229 was raised by RWE Npower on 28 November 2008.
It seeks to allocate transmission loss costs more cost reflectively across generators and demand customers on the GB transmission system. Under the current BSC arrangements, losses are allocated to Parties in proportion to their metered energy volumes, with a uniform allocation of 45% of losses to production accounts and 55% to consumption accounts. The current BSC losses arrangements do not consider the geographic location of generators and customers.

P229 proposes to change the Transmission Losses arrangements in the BSC so a Transmission Loss Factor (TLF) for each BSC Season is calculated for each ‘TLF Zone’. TLFs would be calculated annually for the following year using historical data.

The P229 Proposed solution is essentially the same as that proposed by P203 ‘Introduction of a seasonal Zonal Transmission Losses scheme’, except that it includes provision for offshore nodes.

P229 Alternative, which would add scaling to the P229 Proposed solution with the aim that, in principle, the best outcome for a participant is not to be allocated any costs associated with variable losses. The Alternative solution is based onP204 ‘Scaled Zonal Transmission Losses’.

P203, P204,P198 andP200 were all closed after the Authority stated that it could no longer make a decision on them.


The Panel considered the P229 draft Modification Report at its meeting on 11 March 2010. The Panel confirmed its initial recommendation that neither the P229 Proposed nor the Alternative better facilitate the applicable BSC objectives.

The final Modification Report was sent to the Authority for decision on 12 March 2010. On 28 September 2011 the Authority rejected the P229 Proposed and Alternative Modifications; the Authority’s letter setting out its views, and National Grid’s accompanying notice, can be found below.

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