System Operating Plan (SOP)

As part of our daily planning processes within the ESO control room, the control room strategy team produces a System Operating Plan (SOP) at key demand peaks or troughs throughout the day, at what we call a Cardinal Point (CP). Prior to each CP the Strategy team hand over the relevant SOP to the real-time Energy team, who then use this plan to take real-time operational decisions to balance the electricity system. The SOP is a snapshot of key information that is available to the ENCC at that time of its creation and based on this information provides a flexible strategic plan to ensure the ESO fulfills all its obligations to balance the system. The information within the SOP ensures that the most economic, secure, and flexible plan is developed for that moment in time at the time of handover. The real-time energy team constantly reviews the information within the SOP to ensure it is still relevant as they approach the CP, so that to ensure the operational plan is still valid, and if required modify as needed. On this page, we aim to publish the following SOPs every day ahead of the respective cardinal point: 1A, 1B, 2F/A/B (whichever is the peak of the morning), 3B, 3C & 4B. For further background on the SOP please view our [Introduction to SOPs document](https://www.nationalgrideso.com/data-portal/system-operating-plan-sop/an\_introduction\_to\_system\_operator\_plans), additionally, you can find explanations of the terms used in the SOP in our [SOP Glossary document](https://www.nationalgrideso.com/data-portal/system-operating-plan-sop/glossary\_of\_terms\_used\_in\_system\_operating\_plan). >\*\*NOTE:\*\* We are currently experiencing issues with the quality of the published SOP data in the Data Portal. Our team is actively investigating the matter and working towards a resolution. We apologize for any inconvenience this may have caused. \*\*NOTE:\*\* On 14th January 2026, the below files will get deleted from this dataset as the files are in the non-structured format and some of the data on the below files are already available in System Operating Plan - Data Table data file: 1. Published SOP - Jun 2021 2. Published SOPs September 2020 3. Published SOPs August 2020 4. Published SOPs July 2020 5. Published SOPs June 2020 --- Public Glossary of terms used in a System Operating Plan (SOP) A System Operating Plan is a snapshot in time, usually produced for the peaks and troughs of the Demand Curve (Cardinal Points). The SOP provides a plan to meet System Demand and Reserve Requirements and ensure that any constraints are satisfied. All the information presented in the SOP is based on market submissions and Operating Margin requirements at the time of creation of the SOP. | | Term | Description | Methodology | | ---------------- | ----- | ----------------------- | ------------------- | | Customer Demand | | National 5-minute spot | Calculated by NESO | | Forecast | | demand | | Station Transformer Assumed total national Calculated by NESO station demand | Demand Side Balancing | | NOT VALID ANYMORE | NOT VALID ANYMORE | | ---------------------- | --- | ------------------ | ------------------ | Reserve (DSBR) | Total SOP Demand | | Customer Demand + | Customer Demand + | | ----------------- | --- | -------------------- | -------------------- | | | | Station Transformer | Station Transformer | Standing Reserve A different term for STOR Calculated value by | Requirement (SRR) | | (Short Term Operating | NESO | | ------------------ | --- | ---------------------- | ----- | Reserve). A fixed value depending on the GMT or BST. Standing Reserve The amount of STOR that Calculated by NESO | Availability (SRA) | | is usable is the sum of | systems | | ------------------- | --- | ------------------------ | -------- | the STOR declared available. Standing Reserve Difference between the Automatically calculated | Shortfall | | STOR requirement minus | by NESO systems. | | ---------- | --- | ----------------------- | ----------------- | the STOR usable indicates if there is a standing reserve shortfall. 1 Public Standing Reserve Excess Indicates if there is an Automatically calculated | (SRE) | excess of Standing | by NESO systems. | | ------ | ------------------- | ----------------- | Reserve. Calculated by SRR - SRA. Standing Reserve Wind Automatically calculated Automatically calculated Adjustment value, used to adjust the by NESO systems (Set to | | standing reserve | 0MW/Null as not | | --- | ---------------------- | ------------------ | | | requirement figure to | currently used in | | | take into account the | Operating Margin | | | potential wind | Calculations) | forecasting error Net Positive Regulating Regulating reserve is Calculated by NESO | Reserve (PRG) | designed to cover for | | | -------------- | ---------------------- | --- | expected levels of plant loss plus demand forecast error that occurs for a specified cardinal point between the final SOP production time and real time. Positive Regulating Automatically calculated Automatically calculated | Reserve Wind Adjusted | value to take into | by NESO systems | | ---------------------- | ---------------------- | ---------------- | | (WPRR) | account the potential | | wind forecasting error. | Reserve for Response | Reserve for response is | | | --------------------- | ------------------------ | --- | | (PRE) | the amount of reserve | | that needs to be allocated to synchronised generators so they can be pulled back and instructed to hold frequency response 2 Public Total Positive Reserve Calculation of PRG + PRE. Automatically calculated by NESO systems. Percentage of Standing NOT VALID ANYMORE NOT VALID ANYMORE Reserve Excess Net Negative Regulating Accounts for wind and Calculated by NESO. | Reserve (NRG) | demand forecast errors. | | | -------------- | ------------------------ | --- | Requirement is dynamic based on system conditions. Negative Regulating Automatically calculated Automatically calculated | Reserve Wind Adjusted | value to take into | by NESO systems. | | ---------------------- | ---------------------- | ----------------- | | (WNRR) | account the potential | | wind forecasting error. Negative Response for Negative reserve for Automatically calculated Reserve (NRS) response is the amount by NESO systems after all | | of reserve that needs to | contracted response is | | --- | ------------------------- | ----------------------- | | | be allocated to | subtracted from | | | synchronised generators | requirement | to allow them to be picked up from SEL to hold high frequency response. Total Negative Reserve Calculation of NRG + NRS. Automatically calculated by NESO systems | Maximum Loss | Maximum generation | Manually adjusted by | | ------------- | -------------------------- | --------------------- | | Generation | loss is determined by the | NESO | maximum credible loss on the system at the CP for this SOP. Maximum Loss Demand Maximum demand loss Manually adjusted by | | is determined by the | NESO. | | --- | --------------------- | ------ | maximum credible demand loss on the 3 Public system at the CP for this SOP. Positive Residual Indicates by how much Calculated by NESO | | the NESO has met its | systems and includes | | --- | ------------------------- | ----------------------- | | | positive margin | any manual adjustments | | | requirements in terms of | made by ENCC if | | | SOP demand plus | required | reserve requirements. | Imbalance | Indicates how many Bids | Calculated by NESO | | ---------- | ------------------------- | ------------------- | | | or Offers NESO expect to | systems | be required to meet SOP demand. Negative Residual Indicates by how much Calculated by NESO | | NESO has met its | systems and includes | | --- | ------------------------- | ----------------------- | | | negative margin | any manual adjustments | | | requirements in terms of | made by ENCC if | | | SOP demand plus | required | reserve requirements Contingency A margin of plant that Automatically calculated | Requirement | will be maintained in a | by NESO systems. | | ------------ | ------------------------ | ------------------------ | | | state to be capable of | (Usually 0MW at 4 hours | | | synchronising in | ahead stage) | sufficient time to achieve full output for the relevant Cardinal Point. Operating Margin Provides an indication of Automatically calculated | Surplus | whether the contingency | by NESO systems | | --------- | ------------------------ | ---------------- | requirement for the cardinal point is satisfied Trigger Level This value is used in Automatically calculated | | conjunction with the | by NESO systems | | --- | --------------------- | ---------------- | Contingency Requirement. If the 4 Public Contingency Requirement is not satisfied by the available plant, then based on these trigger levels NESO will consider whether to issue an Electricity Margin Notification (EMN) to the market. Variable value depending on time of year and day. | TEMX | Total Expected | Based on Market | | ----- | -------------------------- | ----------------------- | | | Maximum: Summation of | provided data plus (if | | | maximum MW | required) actions by | | | availability derived from | ENCC | the Maximum Export Limit (MEL) considering any restrictions due to system constraints. | TEOL | Total Expected Operating | Based on Market | | ----- | ------------------------- | ----------------------- | | | Level: Summation of | provided data plus (if | | | expected actual output. | required) actions by | | | The figures are derived | ENCC | from the Physical Notifications (PNs) considering any restrictions due to system constraints. | TEMI | Total Expected Minimum: | Based on Market | | ----- | ------------------------ | ----------------------- | | | Summation of the | provided data plus (if | | | expected minimum MW. | required) actions by | | | The figures are derived | ENCC | from the Stable Export 5 Public Level (SEL) considering any restrictions due to system constraints. | NO1 | Sum of all the non-wind | Automatically calculated | | ---- | ------------------------ | ------------------------- | | | BMUs in the north | by NESO systems | dispatch zone. | NW1 | Sum of all the wind BMUs | Automatically calculated | | ---- | ------------------------- | ------------------------- | | | forecast output in the | by NESO systems | north dispatch zone. | SO1 | Sum of all the non-wind | Automatically calculated | | ---- | ------------------------ | ------------------------- | | | BMUs in the south | by NESO systems | dispatch zone. | SW1 | Sum of all the wind BMUs | Automatically calculated | | ---- | ------------------------- | ------------------------- | | | forecast output in the | by NESO systems | south dispatch zone. A negative value for the Interconnector flow indicates the flow is from UK. | Britned | Expected flow on the | Market provided data | | -------- | --------------------- | --------------------- | BritNed Interconnector based on the latest submitted reference program | EWIC | Expected flow on East | Market provided data | | ----- | ---------------------- | --------------------- | West Interconnector based on the latest submitted reference program. | France | Expected flow on IFA | Market provided data | | ------- | --------------------- | --------------------- | Interconnector based on the latest submitted reference program | IFA2 | Expected flow on IFA2 | Market provided data | | ----- | ---------------------- | --------------------- | Interconnector based on 6 Public the latest submitted reference program Moyle Expected flow on the Market provided data Moyle interconnector based on the latest submitted reference program Nemo Expected flow on the Market provided data Nemo interconnector based on the latest submitted reference program Pumped Storage (PS) Pumped Storage units. Market provided data Can be positive or negative as the unit pumps or generates. Short Term Operating Short Term Operating Manually adjusted by Reserve (STO) Reserve (STOR). NESO if any excess is used to offset Regulating Reserve Small BMUs (SB) Small Balancing Automatically calculated Mechanism Units (BMUs) by NESO systems Total_(TEMX/TEOL/TEMX) Summation of NO1 + NW1 Automatically calculated + SO1 + SW1 + BRITNED + by NESO systems EWIC + FRANCE + INTELEC + INTGRNL + INTIFA2 + INTNSL + INTVKL + MOYLE + NEMO + PS + BAT + STO + SB + SLR. NSL Expected flow on the Market provided data North Sea Link interconnector based on 7 Public the latest submitted reference program Elec Expected flow on the Market provided data Eleclink interconnector based on the latest submitted reference program Batteries (BAT) Output of transmission Automatically calculated connected battery BMUs. by NESO systems Can be positive or negative as batteries import or export MWs. Solar (SLR) Output of transmission Automatically calculated connected solar BMUs. by NESO systems Green Link Expected flow on the Market provided data Green Link interconnector based on the latest submitted reference program Viking Link Expected flow on the Market provided data Viking Link interconnector based on the latest submitted reference program 8 --- Public What is the System Operating Plan (SOP)? As part of our daily planning processes within the NESO control room, the control room strategy team produce a System Operating Plan (SOP)s at key demand peaks or troughs throughout the day, at what we call a Cardinal Point (CP). Prior to each CP the Strategy team hand over the relevant SOP to the real-time Energy team, who then use this plan to take real time operational decisions to balance the electricity system. The SOP is a snapshot of key information that is available to the ENCC at that time of its creation and based on this information provides a flexible strategic plan to ensure NESO fulfils all its obligations to balance the system. It covers: • Commercial information in terms of submitted prices and parameters of available BMUs that could be utilised to balance the system • Any identified transmission constraint issues that may affect the balancing of the system It indicates if any operational decisions (e.g. additional Balancing Mechanism Units are required to meet demand) are needed to be enacted by the energy team. Currently, the SOP contains the following information: • National demand for the Cardinal Point. • An indication of the amount of action is required by NESO in the balance mechanism to meet it required position (demand plus margin) at the cardinal point. Either through bids or offers. • Expected contribution from Interconnectors, Wind, Batteries, Solar and small BMU’s based on submitted data and forecasts. • Reserve requirements - Positive/negative • Amount of Short Term Operating Reserve (STO) available (if CP within contract window). • Our contingency requirements; any shortfall or excess in our margins that are required to be maintained to ensure generation is capable of synchronising in sufficient time to achieve full output for the relevant Cardinal Point. • System Imbalance – Positive/Negative • Largest generation and demand loss on the system at the CP 1 Public This information within the SOP ensures that the most economic, secure and flexible plan is developed for that moment in time at the time of handover. The real time energy team constantly review the information with the SOP to ensure that the information within is still relevant as they approach the CP, so that to ensure the operational plan is still valid, and if required modify as needed. The current aim is to publish the following SOPs every day ahead of the respective cardinal points: • 1A, 1B, 2F/A/B (whichever is the peak of the morning), 3B, 3C and 4B. • Due to the operational nature of the role which manually publishes the data they may not publish on each of the above cardinal points. How to read a SOP? Initially looking at the SOP it appears to be a mass of information, and it should be read in conjunction with the detailed glossary to understand all the terminology used. There is no prescribed approach to reading a SOP, as it depends on the information a person is hoping to extract. The market position for the CP at the time of creation of the SOP will dictate how much balancing the ENCC is anticipating of having to carry out to meet demand plus any required reserve (either upward or downward) considering any transmission issues that may exist. If the market has self-balanced in terms of meeting forecast demand, then the ENCC may only need to take actions to meet reserve requirements or for transmission issues, and this is reflected in the “Imbalance” figure. Obviously, an un-balanced market position will require more actions. The most common information that are extracted from a SOP are: • Cardinal Point time • Forecast demand: - Total (SOP Demand) • The amount of balancing required: - Imbalance (SOP Demand – Total_TEOL) o This will be achieved through Bids or Offers 2 Public • The amount of Margin within the balancing mechanism: - Operating Margin Surplus/Shortfall • The largest Generation Loss on the system at the CP: - Maximum loss (Generation) • The largest demand loss on the system at the CP: - Maximum Loss (Demand) Other information that is now easily available include reserve and response levels and expected contributions from Wind, Interconnectors. 3