Slow reserve
Reserve is needed for frequency management when there is an imbalance between supply of energy and demand for energy.
When instantaneous supply is not enough to meet the demand, the frequency falls; where supply outstrips demand, the frequency rises. Additional generation or demand is needed to re-establish this balance. Initially, this is provided by Frequency Response which initiates automatically according to system frequency. Reserve is then instructed to replace the energy delivered by frequency response in accordance with system requirements.
Slow Reserve (SR) is primarily aimed at reacting to post-fault disturbances to restore energy imbalances to +/- 0.2Hz within 15 minutes of a loss event (generation or demand). For Negative Slow Reserve (NSR), units are instructed to increase demand or decrease generation in full within 15 minutes. The inverse is true for Positive Slow Reserve (PSR). Slow Reserve is open to any technology with the ability to provide a net change in demand/generation of at least 1MW.
Further enquiries:
Email: [email protected]
This document outlines the transition from the legacy Short Term Operating Reserve (STOR) to the new Slow Reserve (SR), which is divided into positive and negative categories, with Positive SR replacing STOR. It details two transition approaches: Hard Stop and Phasing Out.
NESO seeks industry feedback by 5 March 2025 to determine the preferred transition method. Your input is essential for a smooth and efficient transition. Please submit your feedback to through our Slow Reserve transition survey here.
| Document Library | |
|---|---|
| Transition of STOR to Slow Reserve Requirement and Procurement Options | Download |
We have now completed our initial proposed service and procurement design for the new Slow Reserve service, incorporating both BM (Balancing Mechanism) and non-BM (non-Balancing Mechanism) market participants.
Alternatively please contact us here [email protected]
| Name | Published |
|---|---|
| NESO Operational Metering Overview | 20 Nov 2024 |
| Slow and Quick Reserve - webinar slides - 9 March 23 | 16 Mar 2023 |
| Reserve Reform Show & Listen 2 - 26.05.22 | 27 May 2022 |
| Reserve Reform Show & Listen 1 - 28.04.2022 | 29 Apr 2022 |
| Slow Reserve Service Summary - April 22 | 21 Apr 2022 |
| Slow Reserve Feedback Proforma | 14 Apr 2022 |
| Reserve Reform Update - February 2022 | 25 Feb 2022 |
| Reserve Product Reform Consultation | 5 Mar 2021 |
Following our Request for Input on the proposed new Slow Reserve service, find out what's next for the service during our webinar on 11 February at 2pm. We'll deep-dive into the service and procurement design incorporating both Balancing Mechanism and non-Balancing Mechanism market participants.
19 May 2023
ESO has come to the decision to delay the delivery of the new Reserve reform products, Slow and Quick Reserve – originally planned for October and November 2023. As a result, we will not be launching our EBR Article 18 consultation to industry as planned at the end of May.
This decision has been taken in light of the significant changes that would have been required in our existing, legacy balancing systems and processes, given the complexity of the new service designs. In the midst of a complex and rapidly evolving systems change environment, we believe it is more prudent to re-evaluate these changes to consider if implementation into our legacy systems is still appropriate, as opposed to direct implementation into our Open Balancing Platform (OBP).
Postponing the rollout of our new Reserve services grants us the opportunity to re-examine our proposed service designs, evaluate our IT options, and collaborate with you more effectively. This will ensure that the best solutions are delivered and that the necessary updates to our balancing systems are apt for enhancing our operational toolkit and are better aligned with the implementation of our future systems.
In the coming weeks we will be looking to understand the extent to which we review the proposed services designs and IT solutions. We will then communicate how and when we intend to engage with you in this process via the Future of Balancing Services distribution list.
20 April 2023
Last month, we held a webinar on 9 March where we updated industry on our delivery plan and provided a refresh of the services (please refer to the Document Library tab for the documentation and recordings).
This delivery plan indicated launching our EBR consultation towards the end of April with the dependencies being further exploration of system changes and the quantum of change acceptable to market providers as well as the ENCC. We have also noted the feedback on Crossovers from the market and we are still analysing the most optimal solution for the end consumer.
As we are still working through these dependencies and feedback, the EBR consultation will be moved provisionally to the end of May.
We intend to update and confirm our delivery plan for Quick Reserve and Slow Reserve in Future of Balancing Services newsletter.
Slow Reserve Webinar 11 February 2025
Following the webinar held on 11 February 2025, we have shared the slides and a recording of the webinar.
Reserve Reform Update Webinar 19 December 2023
Following the webinar held on 19 December 2023, we have shared the slides and a recording of the webinar.
Further enquiries
Get in touch with the right team within Balancing Services, who are on hand to answer any questions you may have.