Capacity Market auction: Auction Monitor report for T-1 auction for 2026 to 2027

The Capacity Market Auction Monitor, Deloitte, has produced a report in relation to the Capacity Market T-1 auction for the 2026 to 2027 delivery year. --- 2025 one year ahead Capacity Auction (T-1) Delivery Year 2026/27 Auction Monitor Report 6 March 2026 2025 one year ahead Capacity Auction (T-1) Delivery Year 2026/27 Deloitte LLP 6 March 2026 Contents 1 Assurance Report 2 Background and Context 3 Confirmation of Bidders to be awarded Capacity Agreements Appendix A – In-scope Capacity Market Rules (Chapter 5) Appendix B – Outline of Work Performed 1 4 6 13 14 2025 one year ahead Capacity Auction (T-1) Delivery Year 2026/27 Deloitte LLP 6 March 2026 1 Assurance Report ISAE 3000 Independent Reasonable Assurance Report to National Energy System Operator Limited (NESO) (as Electricity Market Reform Delivery Body) on its compliance with selected requirements of the Capacity Market Rules, Regulations and the Auction Guidelines. Scope 1.1 We have performed assurance work over the extent to which the Delivery Body (“DB”) has complied with the selected requirements of Chapter 5 of the Capacity Market Rules and the Auction Guidelines (together the “Rules and Guidelines”) (updated 23 June 2025). In particular, we have considered the rules included in Chapter 5 of the Capacity Market Rules as listed in Appendix A (the “Applicable Rules”). A consolidated version of the detailed Capacity Market Rules is available here: https://assets.publishing.service.gov.uk/media/6911ba14cf24e9250d893e79/i nformal-consolidation-cm-rules-2025.pdf with the subsequent amendments at the time of writing available here:https://www.gov.uk/government/publications/capacity-market-rules. In the context of this Report, the actions of the DB in performing the 2025 one year ahead Capacity Auction (T-1) Delivery Year 2026/27 (“the 2025 T-1 Auction”) is the “Subject Matter” and the Applicable Rules form the “Criteria” against which the Subject Matter has been evaluated. Respective Responsibilities 1.2 The DB as the Responsible Party is responsible for delivering the process and requirements for the 2025 T-1 Auction in accordance with the Capacity Market Rules. Our responsibility, as agreed with the DB, is to assess the actions performed by the DB in performing the 2025 T-1 Auction against the requirements of the Applicable Rules and to independently express a conclusion as to whether the process and actions undertaken by the DB comply with the requirements of the Applicable Rules. Other than as defined in our assurance procedures, we did not audit or otherwise test or verify the information given to us in the course of the Services. 1.3 Work Performed We conducted our work in accordance with the International Standard on Assurance Engagements 3000 (Revised) “Assurance Engagements Other Than Audits or Reviews of Historical Financial Information”. That standard requires that we plan and perform our work to obtain appropriate evidence about the subject matter of the engagement sufficient to support an opinion providing reasonable assurance. 1 2025 one year ahead Capacity Auction (T-1) Delivery Year 2026/27 Deloitte LLP 6 March 2026 An outline of the work we performed is included in Appendix B. Except to the extent expressly stated above, we did not subject the information contained in our Report or given to us by the DB to checking or verification procedures. The procedures we performed were not designed to and are not likely to reveal fraud. Inherent limitations 1.4 We obtained reasonable assurance over the actions performed by the DB in operating in performing the 2025 T-1 Auction against the requirements of the Applicable Rules. Inherent limitations exist in all assurance engagements. Any internal control structure, no matter how effective, cannot eliminate the possibility that fraud, errors or irregularities may occur and remain undetected. The procedures we performed were not designed to and are not likely to reveal fraud. Except to the extent expressly stated, we did not subject the information contained in our Report, given to us by the DB (including bids) or included in the input parameters provided by DESNZ to checking or verification procedures. Basis of Opinion 1.5 We believe that our work performed and evidence obtained provides a reasonable basis for our opinion. Our assurance report has been produced under our letter of engagement with the Responsible Party effective from 26 June 2025. Assurance Conclusion 1.6 In our opinion the actions performed by NESO, in its role as the Capacity Market Delivery Body for Electricity Market Reform, have in all material respects, complied with the relevant sections of the Rules and Guidelines as detailed in Section 1.1 above in respect of the 2025 T-1 Auction held between 09:00 on 3 March 2026 and 13:00 4 March 2026. A list of the Bidders and corresponding Capacity Market Units (“CMUs”) to be awarded Capacity Agreements following the 2025 T-1 Auction is included in Section 4. Independence and Quality 1.7 In conducting our engagement, we have complied with the independence and other ethical requirements of the Code of Ethics for Professional Accountants issued by the International Ethics Standards Board for Accountants and the ICAEW Code of Ethics, which are founded on fundamental principles of integrity, objectivity, professional competence and due care, confidentiality and professional behaviour. Our firm applies International Standard on Quality Management (UK) 1 issued by the Financial Reporting Council and accordingly maintains a comprehensive 2 2025 one year ahead Capacity Auction (T-1) Delivery Year 2026/27 Deloitte LLP 6 March 2026 system of quality control including documented policies and procedures regarding compliance with ethical requirements, professional standards and applicable legal and regulatory requirements. Use of Report 1.8 Our Report has been prepared for the exclusive use of NESO in accordance with the scope agreed within our contract dated 26 June 2025. Our work has been undertaken solely for the purpose of assessing NESO’s compliance with the Rules and Guidelines outlined in Section 1.1 above. Our work was not planned or conducted with any other objective in mind and so cannot be relied upon for any other purposes. Save that a copy of our report may be provided to the Secretary of State for Energy Security and Net Zero and the Gas and Electricity Market Authority and may be published on the www.gov.uk website, our Report is not to be used for any other purpose, recited or referred to in any document, copied or made available (in whole or in part) to any other person without our prior written express consent. To the fullest extent permitted by law, we do not accept or assume responsibility to anyone other than NESO for this report or for the conclusions we have formed. Deloitte LLP Manchester, United Kingdom 6 March 2026 3 2025 one year ahead Capacity Auction (T-1) Delivery Year 2026/27 Deloitte LLP 6 March 2026 2 Background and Context Background 2.1 Electricity Market Reform (“EMR”) is intended, inter alia, to promote investment in low-carbon electricity generation and ensure security of supply. The Capacity Market supports achieving security of electricity supply by providing a payment for reliable sources of capacity. This supplements generators’ electricity revenues, to ensure they deliver energy when needed. This is designed to encourage the investment needed to replace older power stations, provide backup for more intermittent and inflexible low carbon generation sources and support the development of more active demand management in the electricity market. EMR has been implemented through the Energy Act 2013 and the Electricity Capacity Regulations 2014 (as amended) (“the Regulations”). The Capacity Market Rules 2014 (as amended) (“the Rules”) provide the technical and administrative detail for implementing the operating framework set out in the Regulations. As such, the Rules provide a description and procedures regarding the operation of the Capacity Market. National Energy System Operator Limited (NESO) fulfils the role of EMR Delivery Body for the Capacity Market and is responsible for pre-qualifying auction participants, running the capacity auctions, and issuing and monitoring agreements, and for the issuing of Capacity Market notices. Unless otherwise specified herein, words and expressions used in this Report have the same meaning as defined in the Regulations and Rules. Requirement for the Auction Monitor 2.2 In its role as DB for EMR, NESO, pursuant to Chapter 5 of the Rules, is required to appoint a third party to monitor the conduct of each Capacity Auction, referred to as the Auction Monitor. Under the Rules the Auction Monitor is required to provide a report (“Report”) to the Secretary of State for Energy Security and Net Zero (“the SoS”) with a copy to the Gas and Electricity Markets Authority (“the Authority”) which: • Confirms the list of Bidders that should have been awarded a Capacity Agreement; • Sets out whether or not the Auction Monitor considers that the Capacity Market DB and/or the Auctioneer has conducted the Capacity Auction in accordance with the Regulations and the Rules; • If applicable, identifies any actual or potential breach of the Regulations or the Rules or other actual or potential irregularity in the conduct of the Capacity Auction by the Capacity Market DB and/or the Auctioneer; and 4 2025 one year ahead Capacity Auction (T-1) Delivery Year 2026/27 Deloitte LLP 6 March 2026 • If applicable, includes a review of the calculations made and the Auction Monitor’s assessment as to the likely consequences of such actual or potential breach or irregularity. Under Rule 5.14.3(a) the Auction Monitor is required to provide the Report to the SoS. This will be achieved through the Auction Monitor providing the Report to the DB who will send it to the SoS and copy the Report to the Authority. We understand the SoS intends to publish this Report. Basis on which work performed 2.3 Deloitte LLP has been engaged by NESO to perform the Auction Monitor role and report on the performance by NESO (in its role as Delivery Body for the 2025 T-1 Auction) by providing a reasonable assurance opinion under the International Standard on Assurance Engagements (“ISAE”) (Revised) 3000 in respect of the requirements for the Auction Monitor. Our independent opinion has been prepared under ISAE 3000, which provides the structure and internationally recognised framework for undertaking the engagement, leading to a formal assurance opinion which is provided in Section 1 of this Report. Report on Observations 2.4 Where identified during the course of our work, we also report observations relating to the DB’s compliance with selected requirements of Chapter 5 of the Capacity Market Rules and the Data and Auction sections of the Capacity Market Auction Guidelines (‘the Auction Guidelines’ updated 10 February 2026 (available here: https://nationalenergyso- emr.my.salesforce.com/sfc/p/#8d000002dUGC/a/J700000063aH/luaPC19hYD Kn2LyQEl6fFzbDianhUmLykWutdCg00mY), and any other potential irregularity with respect to the conduct of the Capacity Auction. We have no such observations to report. 5 2025 one year ahead Capacity Auction (T-1) Delivery Year 2026/27 Deloitte LLP 6 March 2026 3 Confirmation of Bidders to be awarded Capacity Agreements The 2025 T-1 Auction started at 09:00 on 3 March 2026 and the Clearing Round was Round 15, which closed at 13:00 on 4 March 2026. The Clearing Price of the 2025 T-1 Auction was equal to £5.00, with the aggregate Bidding Capacity of Capacity Agreements of 7,192.317 MW. Based on the outcome of the 2025 T-1 Auction and in accordance with the Capacity Market Rules 2014 published on 1 August 2014 (as amended), we confirm that the following list of bidders and corresponding CMUs1 to be awarded Capacity Agreements were successful in the 2025 T-1 Auction. Table 1. List of Bidders and Corresponding CMUs Awarded Capacity Agreements in the 2025 T-1 Auction Name of Applicant per CM Register CM Unit Name per CM Register ORSTED ESS MERSEY LIMITED Carnegie Road CMU GRIDBEYOND LIMITED Brooke EfW GB2401 GB2405 GB2410 GB2414 GB2416 GB2501 GB2502 GB2504 GB2509 GB2510 GB2527 GB2531 GB2539 GB2542 1 Bidding Company/Group information is taken from the Capacity Market Register. 6 2025 one year ahead Capacity Auction (T-1) Delivery Year 2026/27 Deloitte LLP 6 March 2026 Name of Applicant per CM Register CM Unit Name per CM Register GB2547 GB2552 GB2553 GB2632 GBD010 GBD011 GBD012 GBD020 GBD022 GBD038 GBD048 / GB2548 GX2608 GX2609 GX2610 GX2612 On-Site Energy - Chesterfield Poultry PULSE CLEAN ENERGY UK LIMITED Hirwaun PULSE CLEAN ENERGY SPV ANNING LIMITED Town Lane SIZING JOHN LIMITED SAMBAR POWER LIMITED AIK2A SUSTAINABLE ENERGY LTD ALKANE ENERGY UK LIMITED BATTERY BOX LIMITED VAR013 VAR014 Aikengall IIa Boston Solar Offham Solar BBT1U6 BBT1U8 BBT1U9 BT1U10 BT1U11 BT1U12 URBAN RESERVE STORAGE LIMITED Dellsome Power ALCEMI STORAGE DEVELOPMENTS 4 LIMITED COALB1 School Power 7 2025 one year ahead Capacity Auction (T-1) Delivery Year 2026/27 Deloitte LLP 6 March 2026 Name of Applicant per CM Register CM Unit Name per CM Register LEEMING SOLAR FARM LIMITED Leeming Solar Farm BESS ROBIN HOOD AIRPORT DEVELOPMENTS LIMITED BENT2 AGR SOLAR 2 LIMITED BOAT OF GARTEN BESS LIMITED BOC LIMITED BRAMLEY BATTERY STORAGE LIMITED BRING ENERGY LIMITED BIRMINGHAM DISTRICT ENERGY COMPANY LIMITED BFEN23 BOAT26 TLGUK BRAM26 Battersea BDEC1 BDEC2 EXCEL DISTRICT ENERGY COMPANY LIMITED EDEC BRING ENERGY LIMITED Edinburgh St. James EAST LONDON ENERGY LIMITED ELE - KY ELE - SC LEICESTER DISTRICT ENERGY COMPANY LIMITED LDEC BRYT ENERGY LIMITED BEPCC-2 PCC-1 BRITISH SOLAR RENEWABLES LIMITED Dengie BESS CAPBAL (BRACO) LIMITED CAPBAL (FORFAR) LIMITED CARGILL PLC HD000ACT LTD HB333MIL LTD HD192RAY LTD BRAC24 FORF25 POL CHP Fairholme Iron Acton 3 Mill Hill Rayleigh DALMARNOCK BESS LTD Dalmarnock BESS ENGIE POWER LIMITED FLEXITRICITY LIMITED 8 EGENMX UPDSR1 UPDSR2 UPDSR5 UPDSR6 F18024 FLEX01 2025 one year ahead Capacity Auction (T-1) Delivery Year 2026/27 Deloitte LLP 6 March 2026 Name of Applicant per CM Register CM Unit Name per CM Register FLEX02 FLEX03 FLEX04 FLEX158 FLEX162 FLEX166 FLEX169 FLEX19 FLEX194 FLEX203 FLEX25 FLEX29 FLEX30 FLEX39 FLEX80 FLEX82 FLEX91 ST FERGUS ENERGY LIMITED St Fergus Energy Park ZEPHYRUS GREEN ENERGY LTD Strathallan Wind Farm BLOXWICH ENERGY STORAGE LIMITED NEVENDON ENERGY STORAGE LTD HARMONY SK LIMITED BLOX26 NEVN26 HSKL26 HUMBLY GROVE ENERGY LIMITED Humbly Grove DSR IMPACT POWER LIMITED EMISTA INOVYN CHLORVINYLS LIMITED RuncornERF - Phase 2 POWER ON TECHNOLOGIES LTD LEVELISE LIMITED JOUL19 TSCSW3 LEVC04 LEVC05 LEVC06 LEVC07 LONDONENERGY LTD LondonWaste 9 2025 one year ahead Capacity Auction (T-1) Delivery Year 2026/27 Deloitte LLP 6 March 2026 Name of Applicant per CM Register CM Unit Name per CM Register LOW CARBON UK SOLAR OPERATIONS LIMITED Kimpton BESS FRP MERCIA HOLDCO 2 LIMITED Layer 2 BESS Sandon Brook BESS Shaftesbury BESS Fordbridge Lane Geddington Road Hatton High View Existing POWERTREE (HOLDINGS) LIMITED Hindlip T1 FRP MERCIA HOLDCO 2 LIMITED Sookholme Exist Gen NEWLINCS DEVELOPMENT LIMITED NEWLINCS IWMF NEXTPOWER BOSWORTH LIMITED Bosworth NEXTPOWER HIGH GARRETT LIMITED High Garrett NEXTPOWER SOUTH LOWFIELD LIMITED South Lowfield LITTLE STAUGHTON AIRFIELD SOLAR LIMITED Staughton NEXTPOWER GRANGE LIMITED The Grange NEXTPOWER BINDWELL LIMITED GWENT FARMERS' COMMUNITY SOLAR PARTNERSHIP LIMITED Bindwell Llanwern NEXTPOWER LOWER STRENSHAM LIMITED Lower Strensham EDF ENERGY NUCLEAR GENERATION LIMITED Hartlepool Power Station CMU 1 Hartlepool Power Station CMU 2 Heysham 1 Power Station CMU 1 Heysham 1 Power Station CMU 2 Heysham 2 Power Station CMU 7 Heysham 2 Power Station CMU 8 Torness Power Station CMU 1 Torness Power Station CMU 2 Nurse2 OCT090 OCT091 OCT092 OCT093 NURSLING ENERGY TWO LIMITED OCTOPUS ENERGY LIMITED 10 2025 one year ahead Capacity Auction (T-1) Delivery Year 2026/27 Deloitte LLP 6 March 2026 Name of Applicant per CM Register CM Unit Name per CM Register OCT094 OCT095 OCT096 OCT099 OCT100 OCT101 OCT102 OCT103 OCT109 OCT110 PG2024 PODP05 PODP06 PODP07 PODP08 Rivenhall CMU_CHEGT1 CMU_CHWE-1 CMU_LANB-1 PEAK GEN POWER 2 LIMITED POD POINT LIMITED INDAVER RIVENHALL LIMITED RWE GENERATION UK PLC RWE RENEWABLES UK SOLAR AND STORAGE LIMITED FP LUX SCURF DYKE SOLAR LIMITED SCU003 SEVERN POWER LIMITED SHEAF ENERGY LIMITED Severn Unit 10 Severn Unit 20 SEL2T1 SIMEC LOCHABER HYDROPOWER 2 LIMITED SLH2G1 SOUTH KYLE WIND FARM LIMITED South Kyle Wind Farm Limited SEAGREEN WIND ENERGY LIMITED Seagreen Windfarm Unit 1 Seagreen Windfarm Unit 6 THURROCK POWER LIMITED Thurrock Power Limited THURROCK STORAGE LIMITED Thurrock Storage Limited Thurrock Storage Limited SUTTON BRIDGE POWER GENERATION Sutton Bridge PIVOTED POWER LLP Pivot Power Bredbury 11 2025 one year ahead Capacity Auction (T-1) Delivery Year 2026/27 Deloitte LLP 6 March 2026 Name of Applicant per CM Register CM Unit Name per CM Register DAMSONGREEN ENERGYFARM LIMITED Tye Lane Solar PITKEVEY BATTERY STORAGE LIMITED SG GRI TILN BESS LIMITED VEOLIA UK LIMITED Pitkevy TILN25 Seafield DSR VEOLIA CHP UNIT B VEOLIA CHP UNIT C VEOLIA CHP UNIT E VEOLIA CHP UNIT F VEOLIA CHP UNIT K VEOLIA CHP UNIT L VEOLIA CHP UNIT M VEOLIA CHP UNIT N VEOLIA CHP UNIT P VEOLIA CHP UNIT Q VEOLIA CHP UNITS I VEOLIA CHP UNITS J VOLTALIS UK LIMITED V26_01 GRIDSOURCE (WOBURN RD) LIMITED Woburn Road CORRINGHAM POWER LIMITED Corringham 12 2025 one year ahead Capacity Auction (T-1) Delivery Year 2026/27 Deloitte LLP 6 March 2026 Appendix A – In-scope Capacity Market Rules (Chapter 5) The following Rules included in Chapter 5 of the Capacity Market Rules were considered in performing the assurance work. • Rule 5.3 on the ability of qualified parties to participate in the Capacity Auction • Rule 5.4 on CMUs excluded from the Capacity Auction • Rules 5.5.1 to 5.5.4 and 5.11 on the scheduled timing and duration of the Capacity Auction • Rules 5.5.5 to 5.5.9 on the Capacity Auction format and starting price • Rule 5.5.10 on the publication of pre-auction information • Rules 5.5.11 to 5.5.13 on Demand Side Response CMUs and Bidding Capacity • Rules 5.5.14 to 5.5.17 on the consistency of the register with the pre- qualified parties • Rules 5.5.18 and 5.5.20 on the information provided in each round by Auctioneer • Rule 5.5.21 on the use of backup systems during the Capacity Auction • Rules 5.6 to 5.9 on the calculation of the Capacity Auction results • Rule 5.10 on the list of bidders to be awarded Capacity Agreements • Rule 5.14 on the Auction Monitor role 13 2025 one year ahead Capacity Auction (T-1) Delivery Year 2026/27 Deloitte LLP 6 March 2026 Appendix B – Outline of Work Performed The specific procedures performed were as follows. Table 1. List of Procedures Performed Ref CM Rule Independent checks 1 n/a 2 n/a Check that the version of the Auction System used in the Auction is the same version accepted following User Acceptance Testing (UAT). Check that security controls are in place to prevent unauthorised access to the Auction System. • Confirm that all users are required to have a password and PIN. • Confirm from the audit log that all authorised individuals that viewed the CMUs of an organisation were associated to that organisation. • Confirm that management’s system testing included consideration of security processes. 3 5.3 Check that those Bidders and CMUs that were allowed to participate in the Capacity Auction had the correct access and information loaded on to the Auction System by: • Obtaining a register of qualifying CMUs, with their relevant features, which intend to participate in the Capacity Auction. • Comparing the register to the list of CMUs on the Auction System and confirming that there have been neither additions to nor omissions from the list. • Liaising with the Auctioneer throughout the Auction as to whether they have identified any disqualified CMUs and, if so, confirming that these have been treated as required by Rule 5.3.3. 4 5.4 Check that excluded CMUs do not have access to the Auction System by: • Obtaining list of CMUs that have been withdrawn from a Capacity Auction and register of qualifying CMUs. • Comparing the register to list of CMUs on the Auction System and confirming that those CMUs that have been withdrawn are not included in the Auction System, or that their ability to submit an Exit Bid has been withdrawn. 5 5.5.1 – 5.5.4 5.11 (if applicable) Check on the timing and duration of the Capacity Auction by: • Confirming that the Capacity Auction was held on the date specified in the Auction • Guidelines, with minimal delays. If the Auction was not completed within 5 working days of the first Bidding Window, confirming that the Secretary of State was notified by the Auctioneer. 6 5.5.5 – 5.5.9 Check that the Capacity Auction was run in line with Rules 5.5.5 to 5.5.9 by: • Confirming that the Capacity Auction was run in a manner aligned with the Rules: on a descending clock basis, with a series of price spread Bidding Rounds, with decrements determined by a process issued by the Secretary of State to the Auctioneer, concluding only once the Capacity Auction clears. • Confirming that these spreads are expressed as a range from the Bidding Round Price Cap to the Bidding Round Price Floor, and that the Bidding Round Price Cap of the first round is equal to the Price Cap for the Auction. • Confirming that the price cap for round n+1 is equal to price floor to round n for all rounds as per Rule 5.5.7. • Reproducing the calculation of Clearing Price and the aggregate Bidding Capacity at the Clearing Price. • Check the auctioneer informed the delivery body of the Excess Capacity Rounding Threshold at least 20 days working days before the Auction. 14 2025 one year ahead Capacity Auction (T-1) Delivery Year 2026/27 Deloitte LLP 6 March 2026 Ref CM Rule Independent checks 7 5.5.10 8 9 5.5.11 – 5.5.13 5.5.14 – 5.5.17 Check that, at least 15 Working Days before the first Bidding Round, the Delivery Body published the date and time on which the Capacity Auction would start, the identity, the Excess Capacity Rounding Threshold and De-rated Capacity of all Prequalified CMUs, and the identity of the Auction Monitor. Check that, for each Demand Side Response CMU (DSR CMU), Bidding Capacity equals De-rated Capacity unless the DSR CMU nominated a lower capacity at least 10 Working Days before the first Bidding Window. Check that the correct information for Prequalified New Build CMUs, Refurbishing CMUs and DSR CMUs has been correctly uploaded to the IT Auction System by: • Confirming that the register provided for Rule 5.3 only includes those Prequalified New Build CMUs, Refurbishing CMUs and DSR CMUs that confirmed their intention to participate in the Capacity Auction between 15 and 10 Working Days before the first Bidding Window. • Confirming that the features contained in the register include the duration of Capacity Agreements at the Price Cap for New Build CMUs and Refurbishing CMUs. • Confirming that the system has recorded both the Refurbishing CMU and the Pre- Refurbishment CMU for any Applicant which confirmed that it wanted to participate with its Pre-Refurbishment CMU. 10 5.5.18, 5.5.20 Check that the running of the Auction was in line with the Rules, namely: • For each round that is not the first bidding round, the Auctioneer announced the Bidding Round Price Spread, the Clearing Capacity at the Bidding Round Price Floor, and the Excess Capacity to the nearest Excess Capacity Rounding Threshold (or if the Excess Capacity is below this, the Auctioneer announced that the Excess Capacity is below 1 GW) at the start of the round. • For each round Excess Capacity at price floor was calculated and displayed correctly on the Auction system for each round in line with 5.5.18. • For each round the Auctioneer specified in advance the time that the Bidding Round would begin and end. Check that backup systems are in place to submit bids and that these include safeguards to ensure that the correct bid is submitted. Observe and confirm with the Auctioneer whether the backup systems have been used to submit bids during the Capacity Auction. Review log of calls made/received by the Auctioneer during the Auction. Independently reapply the relevant Capacity Market Rules to calculate the Capacity Auction clearing price and confirm the identification of each CMU to be awarded a Capacity Agreement. • Obtain full details of Exit Bids and Duration Bid Amendments from Delivery Body. • Independently reapply the Rules, as detailed within the Capacity Market Rules 2014 (as amended), and compare the results to those calculated by the Delivery Body. To minimise differences, use the random number generated by the Delivery Body in the case of a tie-break. If differences are identified in the results, review with the Delivery Body and obtain explanations for these differences. • Review Auction System UAT to check the random number process that is applied for the Auction. Confirm that the DB has notified Bidders and the SoS of the provisional results. Confirm that the DB has published the provisional clearing price and the provisional aggregated Bidding Capacity of Capacity Agreements awarded within 24 hours of the auction clearing. Compare the results provided by the DB to the Bidders and the SoS and published to the results of our independent reapplication of the Rules from the previous procedure. Obtain explanations for any differences. Confirm read-only access has been provided to the Auction System for the Auction Monitor throughout the Capacity Auction. Document details of any discussion with Delivery Body of any potential breach identified by the Auction Monitor. Document details of any views expressed by the Auction Monitor following a request by the Delivery Body. Review the pages accessed by those accessing the auction remotely. 11 5.5.21 12 5.6 – 5.9 13 5.10 14 5.14 15 2025 one year ahead Capacity Auction (T-1) Delivery Year 2026/27 Deloitte LLP 6 March 2026 16 2025 one year ahead Capacity Auction (T-1) Delivery Year 2026/27 Deloitte LLP 6 March 2026 Other than as stated below, this document is confidential and prepared solely for your information and that of other beneficiaries of our advice listed in our engagement letter. Therefore you should not, refer to or use our name or this document for any other purpose, disclose them or refer to them in any prospectus or other document, or make them available or communicate them to any other party. 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