This section explains the mechanics of how to access the site and search for information. It is structured as the answers to a series of frequently asked questions, as follows:

This section gives a ‘road map’ of the site. It explains what the main types of data are which can be found on the site, and where this data is derived from. The reports to be found on the site are as follows:

Market View

Electricity Data Summary

National Data
Market Summary
Forecast
Initial Demand Out-Turn
NONBM Instructed Volumes
System Prices
Balancing Services Adjustment Data
Market Index Data

Zonal Data
Zones
Day & Day Ahead (Demand)
Day & Day Ahead (Margin)
Pictorial Representation

BM Unit Data
Physical Data
Dynamic Data
Bid-Offer Data
Derived Data
Balancing Services Volume Data

System Warnings and Other Messages

SO-SO Trades

Trading Operation Report

Credit Default Notices

Much of the data which is displayed on this site cannot be fully appreciated without a basic understanding of the New Electricity Trading Arrangements (NETA), and in particular the Balancing Mechanism (BM) operated by the National Grid Electricity Transmission (System Operator), which is a fundamental part of NETA. This section provides a brief and unofficial summary of the principles under which the BM operates, with links where appropriate to the primary documentation. The topics covered in this section are as follows:

This section gives definitions of the many technical terms which are used on this site. The majority of these are formally defined in other documents, and links to these documents are also given. The terms which are defined are as follows:

ABSVD ABV AOV BD BOAL BOD BPA BSAD DISBSAD EAD EBCA EBVA EEA EI ESCA ESVA FPN FREQ FUELHH FUELINST FUEL TYPE IMBALNGC INDDEM INDGEN INDO INDOD INDODHIGH INDODLOW INDODNORMAL ITSDO MDP MDV MEL MELNGC MID MIL MNZT MZT NDB NDF NDFD NDFW NDO NDZ NIV NONBM NONBM P217 PABV PAOV PAR PDC POWER PARK MODULES QAS QPN RDRE RDRI RURE RURI SBP SBVA SEL SIL SPA SPLD SPLW SSP SSVA TEMP TEMPHIGH TEMPLOW TEMPNORMAL TRIAD TSDF TSDFD TSDFW UABV UAOV WINDFOR

The set of reports which is available is described in the Overview of the main pages. These allow you to investigate events in the Balancing Mechanism at the overall market level, and then to drill down to look in more detail at the operation of individual BM Units. For an initial explanation of the concepts involved, please see the Market Principles section of the site.

Some reports, such as the BM Unit ones, require user input before running. For example you may need to specify a BM Unit Identifier and date. The formats you should use are specified in this help text.

The Low Grade website features a different page layout, a different menu system, improved usability features and other features not available on the High Grade BMRA service.

Where features described in this help text are specific to the Low Grade service, this is indicated by the Low Grade Icon.

If you are not sure what BM Unit Identifier(s) to use, you can use the BM Unit search facility. The Low Grade website additionally provides active dropdown list of values for this field where it is relevant to the report which has been requested.

A list of all BM Units and Ids and BSC Parties can also be found on the ELEXON website, as downloads from http://www.elexon.co.uk/marketdata/staticdata/CRSRegistrationData/default.aspx

• For the Physical, Dynamic, Bid-Offer and Derived pages: Only 1 Settlement Period can be specified (i.e. the wildcard character cannot be used in that field)
  
• No charts or graphs will be displayed, just tabulated data, but this data may be reordered by using drop-down list boxes and clicking the Go button
  
• For the High Grade Site only the number of BM Units retrieved cannot exceed 50.

Internet Explorer Users

1. From the menu bar select 'File' then 'Save As...'
2. This opens a 'Save' dialog box
3. Select a location to save the file to
4. Enter a suitable name into the 'File name' box, e.g. csv or csv.txt
   Important - If you enter a file extension it must be .txt
5. Change the 'Save as type' to Text File
6. Click 'Save'

• National Data
• Zonal Data
• BM Unit Data
• System Warnings and other messages (available under the General menu on the low Grade site)

• the date the last Demand Forecast was issued
• the date and period of the latest Derived Data and hence System Prices
• the date and time of the last System Warning

1. Enter the BM Unit Identifier in the text box
2. Click the (Add) Button.

The page is divided into distinct sections that can be reached by either scrolling down the page or directly by clicking on the section description in the menu on the left of the page. Each section can be toggled from display by ticking and unticking the checkbox next its lefthand menu entry. These checkbox settings are stored in a Cookie so that the page content settings are retained across browser sessions.

The page sections are as follows:

• System Warnings - Lists the System Warnings relating to system problems or imminent demand reductions that are still in effect for time ranges that cover today and tomorrow.
  
  
• Peak Demands - Lists the TSDF peak values for yesterday, today and tomorrow, and the peak ITSDO value for yesterday.
  
  
• Indicative Triad Demand Information - Lists up to 3 peaks of ITSDO data from either the current or previous TRIAD and up to 3 peaks of TSDFW data from the current or future TRIAD. The ITSDO peaks must have 10 clear days of separation between them and are sourced from historic dates in either the current Triad Season if the current date falls within a Triad Season or the previous Triad Season, if the current date falls outside a Triad Season. The TSDFW peaks will not be in consecutive weeks and are sourced from forthcoming dates in either the current Triad Season if the current date falls within a Triad Season or the next Triad Season, if the current date falls outside a Triad Season. Note that there may not always be sufficient temporal separation to provide 3 peaks.
  
  
• Recent System Prices - Lists the maximum SBP and the time that the peak occurs, and the minimum SSP and the time that the peak occurs, for today and the previous 3 days.
  
  
• Market Imbalance - Graphs the NIV values for yesterday and today.
  
  
• System Prices - Graphs the SBP and SSP values for yesterday and today.
  
  
• System Demand - Graphs the TSDF and ITSDO values for yesterday, today and tomorrow.
  
  
• Rolling System Frequency - Graphs the last 60 minutes of FREQ data. This section also allows the current data to be displayed in a table in a pop-up page from where a rolling 48 hours of historic data may also be downloaded. System Frequency data is not available on any other BMRS webpage.
  
  
• Rolling System Demands - Graphs the System Demand derived as the sum across all fuel types in the FUELINST data received over the last 60 minutes. Note that negative Interconnector flow values (exports from the GB Transmission System) are capped at zero.
  
  
• Day/Day Ahead Demand & Gen - Graphs the TSDF and INDGEN values for today, tomorrow and the day after.
  
  
• 2-14 Day Ahead Demand - Graphs the TSDFD values for 2 - 14 days ahead.
  
  
• 2-14 Day Ahead Surplus - Graphs the SPLD values for 2 - 14 days ahead.
  
  
• Long Term Surplus - Graphs the SPLW values for 2 - 52 weeks ahead.
  
  
• Temperature Data - Graphs a rolling 3 months of TEMP, TEMPNORMAL, TEMPHIGH and TEMPLOW data. This section also allows the current data to be displayed in a table in a pop-up page from where a rolling 6 months of historic data may also be downloaded. Temperature data is not available on any other BMRS webpage.

  Effective temperature (TE) is a variable that is used in National Grid and the energy industry generally to estimate the variation of demand in relation to temperature change. Actual weather data is received by National Grid from National Grid's weather data provider for 6 weather stations around the UK (Heathrow Bristol, Birmingham, Leeds, Manchester and Glasgow). TE12 is the weighted average TE of these 6 weather stations at 12:00 hrs calculated using the formula below.

  TE measured in ^oC is the average of a moving average temperature T0 and the TE of 24 hours before.

  TE_t = 0.5 (T0_t + TE_t-24)

  Where T0_t at hour t is the average spot temperature of the 4 hours immediately before hour t =

  
  
  
• Peak Wind Generation Forecast - Lists the peak WINDFOR value, the time of the peak and the total peak capacity of all visible windfarms (ie. those that have operational metering and are included in the latest forecast process). This section also allows details of the current set of Power Park Modules to be downloaded. Wind Forecast data is not available on any other BMRS webpage.
  
  
• Wind Forecast Out-turn - Graphs the initial and latest WINDFOR values as bars and the Wind component of the FUELHH data for yesterday, today and tomorrow. This section also allows the current data to be displayed in a table in a pop-up page from where it may also be downloaded. Wind Forecast and Out-turn data is not available on any other BMRS webpage.
  
  
• Generation by Fuel Type (table) - Lists the latest FUELINST and FUELHH values broken down by fuel type. In addition, a rolling 24 hour MWh value derived from the appropriate FUELHH values is shown. As this section is concerned with the breakdown by fuel type of total positive generation to meet all Transmission System Demand, any fuel type categories with negative values will be capped to zero in this section. For each timeframe, the generation total is calculated and shown and the percentage of that total represented by each each fuel type is calculated. This section also allows a rolling 24 hours of FUELINST data to be displayed in a table in a pop-up page from where it may also be downloaded.
  
  
• Generation by Fuel Type (graph) - Graphs a rolling 24 hours of FUELHH values broken down by fuel type. As this section is concerned with the breakdown by fuel type of total positive generation to meet all Transmission System Demand, any fuel type categories with negative values will be capped to zero in this section. This section also allows the current data to be displayed in a table in a pop-up page from where a rolling 3 months of historic data may also be downloaded. Generation by Fuel Type data is not available on any other BMRS webpage.
  
  
• Daily Energy Transmitted - Graphs a rolling 3 months of INDOD, INDODNORMAL, INDODHIGH and INDODLOW data. This section also allows the current data to be displayed in a table in a pop-up page from where a rolling 6 months of historic data may also be downloaded. Daily Energy data is not available on any other BMRS webpage.
  
  
• Average Half Hourly Interconnector Flows - Graphs the Interconnector components of the FUELHH data for yesterday and today. This section also allows the current data to be displayed in a table in a pop-up page from where a rolling 30 days of historic data may also be downloaded. Interconnector Out-turn data is not available on any other BMRS webpage.

• Market Depth - This page displays the IMBALNGC, Offer Volume, Bid Volume, Accepted Offer Volume (AOV), Accepted Bid Volume (ABV), Unpriced Accepted Offer Volume (UAOV) and Unpriced Accepted Bid Volume (UABV) across the entire Balancing Mechanism. This page publishes data as it becomes available, from the first period of the previous day up to the current period of today. Note that at any given time the data for the current day will be incomplete, as the different data items displayed are received from the System Operator or calculated within the BMRS in differing timescales. For example, the IMBALNGC data for a given Settlement Period is received in advance of the Bid and Offer Volumes, which are not received until Gate Closure; and the remaining values cannot be calculated until after the end of the Settlement Period.
  
  
• Historic Market Depth - Enter a (historic) date to view the Market Depth Data for that day (if no data is available for the date requested an error will be returned). The set of data which is displayed will show all of the items which were defined for the date in question.
  
  
• Market Activity - This page displays the latest Bid/Offer Acceptances (BOAs) which have been recorded by the System Operator for all BM Units. For each BOA the BM Unit will be identified, together with the Acceptance ID allocated by the System Operator, the time at which the BOA was issued and the time at which delivery of the BOA must commence (the times are usually only a few minutes apart). The details are listed in reverse chronological order (i.e. most recent first) from top to bottom, and from the left column to the right column. When data reaches the bottom of the far right column, data will begin to overwrite previous data from the top of the left column.
  
  
  • Near Real Time - The Market Activity chart will automatically update. New acceptances will appear in red.
    
  • Latest / Low Grade - The 84 latest acceptances are displayed. These may stretch back over a number of periods.
  
  
  The information given on the Market Activity screen is intended to allow the individual BOAs to be cross-referenced to the individual BM Unit data (see below)


• Historic Market Activity - Enter a date and a Settlement Period number to view the list of BOAs issued for all BM Units for that period. Note that the wildcard character (*) is not acceptable here (because of the large number of BOAs which would be returned) – a valid Settlement Period number must be entered.
  

• Day and Day Ahead (Demand) - This chart displays the National Demand Forecast (NDF), Transmission System Demand Forecast (TSDF), Indicated Demand (INDDEM) and Indicated Generation (INDGEN) data for the current and following days, in both chart and tabular form. Initial National and Initial Transmission System Demand Forecasts for the following day are normally received by 9a.m. and are published on the BMRS as soon as they are received (the data is produced by the System Operator for a period known as an Operational Day, which runs from 5 a.m. to 5 a.m., and is displayed accordingly). The MELNGC, IMBALNGC and TSDF elements of this information DO take into account Station Transformer Load, Pump Storage Demand and Interconnector flows, but the NDF excludes them. Note that the Initial Day and Day Ahead Transmission System Demand forecast (9 a.m.) assumes a value of zero for the Interconnector and Pumped Storage Demand components.
  
  
• Day and Day Ahead (Margin) - This page displays the Indicated Margin Data and Indicated Imbalance data for the current and following days, in both chart and tabular form. Like the Day and Day Ahead (Demand) forecast, the data displayed in this forecast is updated for an Operational Day at a time. The MELNGC and IMBALNGC elements of this information DO take into account Station Transformer Load, Pump Storage Demand and Interconnector flows.
  
  
• 2 - 14 Day Ahead - This page displays the forecasts produced each Business Day by the System Operator of the National Demand (NDFD), Transmission System Demand (TSDFD) and National Surplus (SPLD) for the predicted peak period in each of days 2 - 14 ahead. These forecasts are produced in accordance with Operating Code 2 of the Grid Code. The latest forecast available is always displayed. These forecasts assume zero value for Pump Storage Demand and Interconnector flow values. The Transmission System demand forecast includes Station Transformer Load (see note below). No zonal forecasts are provided at these timescales.
  
  
• 2 - 52 Week Ahead - This page displays forecasts produced each Thursday by the System Operator of the National Demand (NDFW), Transmission System Demand (TSDFW) and National Surplus (SPLW) for the predicted peak period in each of weeks 2 - 52 ahead (commencing 2 weeks after the current day). Week 1 on the chart refers to the first week of the year and a week begins on Monday and ends on Sunday. Therefore, a calendar year may have 53 weeks (the first calendar week to contain 4 or more days in the new year calendar year is defined as week 1). After week 52 (or 53), the chart wraps back to week 1. The latest forecast available is always displayed. These forecasts assume zero value for Pump Storage Demand and Interconnector flow values. The Transmission System demand forecast includes Station Transformer Load (see note below). No zonal forecasts are provided at these timescales.

To summarise: The files received from 0000 to 1130, other than the file received at 0900, contain values from their Target Time (the time by which they should be received) through to 0500 on D+1 (i.e. over this time range the file coverage goes from 58 values down to 41 values). The files received from 1200 through to 2330 contain values from their Target Time to 0500 on D+2 (i.e. over this time range the file coverage goes from 82 values down to 59 values). The files received at 0900 each day contain only the Initial National Demand Forecast data and Initial Transmission System Demand Forecast data for the period 0500 on D+1 to D+2.

Although data is issued half-hourly, the underlying demand forecast data is not updated as regularly as this. In general the demand forecasts will be updated by the following target times for the time ranges indicated:

• 02:00 - Data from 02:00 on D to 05:00 on D+1
• 10:00 - Data from 10:00 on D to 05:00 on D+1
• 16:00 - Data from 05:00 on D+1 to 05:00 on D+2
• 16:30 - Data from 16:30 on D to 05:00 on D+1
• 22:00 - Data from 22:00 on D to 05:00 on D+2

Between these target times the demand forecast may be updated for operational reasons where required.

BMRA will receive Long Term Forecast data at set daily and weekly times as described in the table below. Note that if the day on which a week forecast(NDFW, SPLW) is due falls on a public holiday, the forecast will be produced on the last Business Day prior to the holiday.

• Yesterday/Today - Initial Demand Out-Turn page displays the Initial Demand Out-Turn (INDO) and the Initial Transmission System Demand Out-Turn (ITSDO) data received from the System Operator for the first period of the previous day to the most recently completed period of today. This display is updated following the end of each Settlement Period as the latest figure is received from the System Operator.
  
• Historic - Enter a date (if no data is available for the date requested an error will be returned) to view the set of INDO and ITSDO data for the day in question.
  

• Yesterday/Today - This page displays the NONBM STOR Instructed Volume data (NONBM) received from the System Operator for the first period of the previous day to the most recently completed period of today. This display is updated following the end of each Settlement Period as the latest figure is received from the System Operator.
  
• Historic - Enter a date (if no data is available for the date requested an error will be returned) to view the set of NONBM data for the day in question.
  

• Yesterday/Today - The System Prices page displays the indicative System Sell Prices and System Buy Prices from the first period of the previous day to the period of today for which the calculations have most recently been completed. . It also includes Balancing Services Adjustment Data, or BSAD, used in each calculation along with a number of other important derived values. The list of additional derived values varies between pre and post P217 Settlement dates. This page is self maintaining ().The page also displays links to underlying data that provide a drill down facility to display data that impacts the corresponding settlement period. It consists of the following items:
  • Disaggregated BSAD, or Balancing Services Adjustment Actions (for post-P217 Settlement dates);
  • A detailed description of the System Price calculation's Stack data (for post-P217 Settlement dates);
  • Physical, Bid-Offer, BSV, Derived, and Acceptance for all BM Units that impact the corresponding settlement period

• Historic - Enter a date (if no data is available for the date requested an error will be returned) to view the set of indicative System Prices for the day in question.The format of the page differs for pre and post P217 Settlement dates.

• Enter a Settlement Date and Period (if no data is available only the structure of the tables on this page will be provided) to view a detailed breakdown of the indicative System Price calculation's Stack for the period in question. The Buy and Sell Stacks are displayed separately. Each Stack lists all accepted actions included in the System Price calculations, including the System Actions (Bid-Offer Acceptance Volumes and Balancing Service Adjustment Actions) showing the initial data along with details of how the indicative price calculation processing affects each item's volume and price. A summary block at the top of the page shows how the results of the Stack processing and the Market Index Data processing are combined to produce the final Indicative System Prices. The Detailed System Price data is only available for post P217 Settlement dates.

• Yesterday/Today - This page displays the latest BSAD data received by the BMRA. Note that BSAD values displayed in this web page may differ from those displayed in the System Prices web page. The BSAD values displayed in the System Prices web page are the actual values used in the calculation of those prices and may have been superseded by later values received by the BMRA. This page displays the latest BSAD data received by the BMRA. The page also displays links to associated Disaggregated BSAD data for the corresponding settlement period where such data exists (for post P217 Settlement dates only). This page is self maintaining.

• Historic - Enter a date to view previous BSAD data. This page displays the latest Historic BSAD data received by the BMRA. Note that BSAD values displayed in this web page may differ from those displayed in the System Prices web page. The BSAD values displayed in the System Prices web page are the actual values used in the calculation of those prices and may have been superseded by later values received by the BMRA. The page also displays links to associated Disaggregated BSAD data for the corresponding settlement period where such data exists (for post P217 Settlement dates only).

• Latest - This page displays the latest Market Index Data received and published by the BMRA for settlement dates today and yesterday. If data is received after the relevant calculation has begun, then it will be rejected by the BMRS, and not published.
  
  Where Market index Data Volume passed to BMRS is found to be below the defined Individual Liquidity Threshold for the MIDP and is non-zero, then the BMRS will consider the Volume, and associated Price, to be zero for that Settlement Period, and publish it as such. Where no Market Index Data is received then no data will be published, and the BMRA will use a default value of zero, for the Volume and Price values, in the related calculation. System Messages will be published to indicate where an MIDP has failed to supply Market Index Data in time for a particular calculation.
  • - The chart will automatically update.
    
    
• Historic - Enter a date and period to view previous Market Index Data.

• Near Real Time - Enter the BM Unit Identifier to receive physical data as soon as it is available.
• Latest / Low Grade - The Latest chart will display the physical data 2 periods ahead of the current period, i.e. the period for which Gate Closure has just occurred.
• Historic - To view previous data of a BM Unit, enter the BM Unit Identifier, the date and Settlement Period and the data will be displayed (if you are unsure of which date format to use, click here). To retrieve data for all periods in a day, enter a * in the Period number field.

• Near Real Time - Enter the BM Unit Identifier to receive the data as soon as it is available.
• Latest / Low Grade - The Latest chart will display data for the current period.
• Historic - To view previous data of a BM Unit, enter the BM Unit Identifier, the date and Settlement Period and the data will be displayed (if you are unsure of which date format to use, click here). To retrieve data for all periods in a day, enter a * in the Period number field.

• Near Real Time - Enter the BM Unit Identifier to receive the data as soon as it is available.
• Latest / Low Grade - The Latest chart will display the physical data 2 periods ahead of the current period, i.e. the period for which Gate Closure has just occurred.
• Historic - To view previous data of a BM Unit, enter the BM Unit Identifier, the date and Settlement Period and the data will be displayed (if you are unsure of which date format to use, click here). To retrieve data for all periods in a day, enter a * in the Period number field.

• Near Real Time - Enter the BM Unit Identifier to receive the data as soon as it is available. This page is self maintaining ().
• Historic - To view previous data of a BM Unit, enter the BM Unit Identifier, the date and Settlement Period and the data will be displayed (if you are unsure of which date format to use, click here). To retrieve data for all periods in a day, enter a * in the Period number field.

• Historic - To view historic data for one or more BM Units, enter the BM Unit search criteria, the settlement date and period and the data will be displayed. (If you are unsure of which date format to use, click here). To retrieve data for all periods in a day, enter a * in the Period number field.

Note that System Warnings relating to System Operator to System Operator Trades are only displayed on the SO-SO Trades page.

A subset of System Warnings filtered according to pre determined rules to identify the most important System Warnings is also available on the Electricity Data Summary page.

• - The table will automatically update.

• Forwards and futures markets that allow contracts for electricity to be struck over timescales ranging from several years ahead to on-the-day markets;
• A Balancing Mechanism by which the System Operator, accepts offers and bids for electricity close to real time to enable it to balance supply and demand; and
• An Imbalance Settlement process for making payments to and from those whose contracted positions do not match their actual metered electricity production or consumption and for clearing certain other costs of balancing the system.

• BSC: Items defined within the Balancing and Settlement Code (http://www.elexon.co.uk/bscrelateddocs/BSC/default.aspx) . These items are denoted by BSC. In many cases the definition of the item is to be found in one of the Glossary sections, which are annexes to Section X of the BSC. In other cases a reference is given to the appropriate location within the BSC.
• GRID CODE: Items defined within the Grid Code (http://www.nationalgrid.com/uk/Electricity/Codes/gridcode/). Some of these items are formally defined in the Glossary and Definitions (GD) section of the Grid Code; but a number of those which relate specifically to the BM are to be found in the Appendices to Balancing Code 1 (BC1). The best description of the BSAD and ABSVD data items is to be found in the BSAD Methodology and ABSVD Methodology, respectively, which are also published on the above web site (within the Balancing Services section of the site, under Transmission Licence Condition C16 Statements).
• BMRS: Items derived within the BMRS (http://www.elexon.co.uk/changeimplementation/ImplementationProgrammes/CVA/implementedreleases/default.aspx). These items are denoted by BMRS. The derivation of these items is given in the User Requirement Specification for the BMRS, which is published on the ELEXON web site (select the latest Implemented Release, as identified on the front page of this BMRS web site, to access the list of available documentation).

Modification P194, introduced on 2 November 2006, retained the mechanism introduced by P78 but further restricts the amount of priced balancing actions considered within the Main System Price calculation by employing a process known as PAR Tagging. This process selects the set of most expensive priced actions which are not De Minimis, Arbitrage, CADL or NIV Tagged whose combined volume does not exceed a defined upper limit (the Price Averaging Reference volume). A more detailed description is given within the BMRA URS.

This represents the initial value of the Acceptance Volume before any System Stack processing has been carried out on it.

This value represents the amount of the associated Acceptance Volume which was not excluded from the System Price Stacks by De Minimis Tagging, Arbitrage Tagging and/or NIV Tagging, and which was Classified as Second-Stage Unflagged and therefore not subject to the Replacement Price.

Modification P217, introduced on 5 November 2009, modified the previous mechanism for calculating the Main System Price by introducing the following concepts:

• Disaggregated BSAD (Balancing Service Adjustment Actions);
• The SO-Flag to indicate where System Actions that are potentially taken for reasons other than balancing the short-term energy imbalance of the Transmission System;
• The Classification of System Actions;
• The Re-pricing of System Actions.

The Price Averaging Reference Volume is used to define a limit on the total volume of priced actions which are not De Minimis, Arbitrage, CADL or NIV Tagged that can be used to calculate the Main Price. The value of PAR is reported on the website.

• The day ahead forecasts supplied by generators and the standard deviation of these forecasts.
• The System Operator’s demand forecasts and the standard deviation of these forecasts.