Imbalance Pricing

Imbalance Pricing

Pricing and related data used in BSC processes includes:

  • System Sell Price and System Buy Price
  • Market Index Price and Volume
  • Parameters used in the calculation of System Prices (Energy Imbalance Price):
    • PAR – Price Average Reference Volume
    • DMAT – De Minimis Acceptance Threshold
    • CADL – Continuous Acceptance Duration Limit
    • MIDS – Market Index Definition Statement

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

There are price reporting agents outside of ELEXON that can provided this information. ELEXON’s System Prices are for Energy Imbalances after the delivery point rather than  wholesale trading prices.

System Sell Price and System Buy Price

The System Sell Price (SSP) and System Buy Price (SBP) are the ‘cash-out’ or ‘Energy 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

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.

How are System Sell Price and System Buy Price calculated?

For each half hour trading period, depending on the net position of National Grid Transmission System, 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.

Imbalance Pricing Guidance

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

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

As Settlement data is retrieved and information becomes finalised, more accurate data is published on the ELEXON Portal. You can obtain SSP and SBP (in £/MWh) and the Net Imbalance Volume (NIV) (in MWh) for every Settlement Period in a particular day.

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  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 is 500MWh and may only be amended by an Approved Modification.

De 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  the BSC Panel may review it from time to time.

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 Ofgem’s approval.

Continuous Acceptance Duration Limit (CADL)

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

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

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 Ofgem’s approval.

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 in the short-term market.

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 Individual Liquidity Threshold (ILT) and (time and product) weightings parameters are published on the ELEXON Portal.

The Market Index Definition Statement is reviewed by the BSC Panel at least once a year. 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 Ofgem.