Different pricing and related data used in BSC processes include:

• System Sell Price and System Buy Price
• Market Index Data Volume and Price
• Parameters used in the calculation of System Prices (Energy Imbalance Price):
• PAR Volume value
• DMAT value
• CADL value
• MIDS Parameters

Where can I find wholesale prices of electricity in Great Britain?

ELEXON does not have any involvement in the setting of these. An indication of wholesale prices could be obtained from a Power Exchange, for example APX Power UK, or from electricity price reporting organisations.

System Sell Price and System Buy Price

The System Sell Price (SSP) and System Buy Price (SBP) are the ‘cash-out’ or ‘imbalance’ prices that are used to settle the difference between contracted generation or consumption and the amount that was actually generated or consumed in each half hour trading period.

Pricing data and values

This page provides information and guidance about the above. If you want the data and values for any of them, please visit the ELEXON Portal.

SSP is paid to BSC Trading Parties who have a net surplus of imbalance energy, and SBP is paid by BSC Trading Parties who have a net deficit of imbalance energy.

These prices are designed to reflect either the prices associated with the Balancing Mechanism Bids and Offers selected by National Grid to balance the energy flows in the Transmission System, or to reflect the prices associated with the sale and purchase of (short-term) energy ahead of Gate Closure (set at one hour before each half hour trading period) in the forwards and spot markets.

Imbalance Pricing Guidance

How are System Sell Price and System Buy Price calculated?

For each half hour trading period one of the ‘cash-out’ or ‘energy imbalance’ prices (System Sell Price and System Buy Price) will be associated with Balancing Mechanism Bids and Offers. In this case the price will be known as the Main Price. The other price will be derived from short term energy trades and is known as the Reverse Price.

Where can I get System Sell Price and System Buy Price data?

Indicative SSP and SBP is reported on BMReports.com (BMRS)

As Settlement data is retrieved and information becomes finalised, more accurate data is published on the ELEXON Portal. There you can obtain SSP and SBP (in £/MWh) and the Net Imbalance Volume (NIV) (in MWh) for every Settlement Period in a particular day since 2004. These values are calculated at the SF (Settlement Final) Settlement Run.

Market Index Data Volume and Price

Market Index Data (MID) is used in the calculation of the Reverse Price for each Settlement Period, and reflects the price of wholesale electricity in the short-term market. You can find an explanation of how it is calculated and used in the Market Index Definition Statement (MIDS).

MID Volume (in MWh) and Price (in £/MWh) for every Settlement can be obtained from the ELEXON Portal.

System Prices (Energy Imbalance Price) parameters

PAR Volume

The Price Averaging Reference (PAR) Volume was introduced on a ‘Settlement Period’ basis for P194 ‘Revised Derivation of the ‘Main’ Energy Imbalance Price’ as amended by P205 ‘Increase in PAR Level from 100 MWh to 500 MWh’ on 2 November 2006. PAR is used to tag Bid-Offer acceptances such that a maximum volume of PAR MWh is used to set the Main Energy Imbalance Price. The value of PAR may only be amended by an Approved Modification.

Minimis Acceptance Threshold (DMAT)

The De Minimis Acceptance Threshold is a parameter used to eliminate Bid/Offer acceptances of small volume (currently less than 1 MWh).

This value is written into the text of BSC Section T Paragraph 1.7 with the stipulation that the BSC Panel may review it from time to time. DMAT was introduced in the implementation of P010 ‘Eliminating Imbalance Price Spikes Caused By Truncating Effects’ (raised by the Transmission Company) on 11 May 2001.

Proposed revisions to the value of DMAT are consulted upon with the Transmission Company and Trading Parties before a Panel determination is made, and are subject to approval by the Authority.

Continuous Acceptance Duration Limit (CADL)

CADL is used to remove short duration Bid-Offer acceptances, associated with system balancing actions, from the Energy Imbalance Price calculation.

A Bid-Offer acceptance relating to any given Balancing Mechanism (BM) Unit will be removed from the system price calculation if it has duration of less than the CADL value in minutes. The value of CADL is currently 15 minutes.

CADL was introduced into the BSC as part of the implementation of P018 ‘Removing/Mitigating the Effect of System Balancing Actions in the Imbalance Price’, in September 2001. CADL is defined in BSC Section T Paragraph 3.1B.

The BSC Panel may revise the value of CADL after consulting with BSC Parties but subject to the approval of the Authority.

Market Index Definition Statement (MIDS) Parameters

The Market Index Definition Statement (MIDS) defines two main parameters. These are the Individual Liquidity Threshold (ILT) and (time and product) weightings.

Market Index Data is used in Settlement to calculate a price, expressed in £/MWh in respect of each Settlement Period which reflects the price of wholesale electricity in Great Britain for delivery in respect of that Settlement Period in the short term market circumstances where the levels of liquidity in the market during that period are not exceptionally low.

The Market Index Definition Statement (MIDS) defines the parameters for use by the Market Index Data Provider (MIDP) in the provision of Market Index data (MID) to the Settlement Administration Agent (SAA). The MIDS was approved for use by the Authority on 11 March 2003 as part of Approved Modification Proposal P078 ‘Revised definitions of System Buy Price and System Sell Price’.

The Market Index Definition Statement is available on the BSC & Related Documents page of the website. The Individual Liquidity Threshold (ILT) and (time and product) weightings parameters are also published on the ELEXON Portal.

The Market Index Definition Statement is reviewed by the BSC Panel at least once every 12 months. Any proposed changes are consulted upon with BSC Parties and other interested Parties before the Panel determines that a change is to be made. A change to the MIDS is subject to approval by the Authority.