Replacement Reserve (RR)

Replacement Reserve is a harmonised service across participating European TSOs for the provision of both an increase and decrease of active power.

Latest updates

26 Nov 2021 - Cost-benefit analysis report for a GB Replacement Reserve product.

22 Jul 2021 - Update on cost-benefit analysis (CBA) being conducted for viability of a GB-only RR product.

24 Mar 2021 - Update on decision to conduct further cost-benefit analysis (CBA), agreed with the TERRE Implementation Group.

Previous updates

15 Jan 2021 - Open letter on progress made by the new TERRE Implementation Group.

11 December 2020 - Update on establishment and progress of the new TERRE Implementation Group, and the latest phase of system testing.

18 November 2020 - An open letter to the industry from Ofgem was published on 6 November. This addresses the challenges being experienced in achieving GB Go-Live in the new European Replacement Reserve (RR) market. In response to Ofgem's letter, NGESO has provided an update, including next steps, which we hope market participants will find helpful.

4 September 2020 - Unfortunately, it is now not possible to facilitate GB participation in RR before the end of 2020.

5 May 2020 - Following our industry webinars of 7 & 16 April on ‘Getting ready for TERRE’, presented jointly with ELEXON, these materials are available:

  • Recording of part 1 (40 mins) - Introduction, Pre-Qualification & participation, data submissions and first Q&A

  • Recording of part 2 (37 mins) - Settlement, testing, next steps and second Q&A

  • Slides from the presentation

  • Q&A  consolidated from both webinars

24 April 2020 - We have published a note on the delay to the implementation in Great Britain of access to the European Replacement Reserve (RR) market until the end of October at the earliest. 

27 November 2019 - Ofgem have granted NGESO a derogation on the implementation of the European platform for the exchange of balancing energy from replacement reserves.

What is Replacement Reserve?

As part of the Electricity Balancing Guidelines, which aims to establish a pan-European market for Balancing Energy, a new product has been created, RR, which can be used across participating TSOs.

What is Wider Access to the BM?

Alongside RR, changes are being made to the Balancing Mechanism to make it more accessible to non-traditional providers and aggregators. Participants interested in Wider Access are able to pre-qualify using the same links on the right hand side and further information on Wider Access can be found here.

Who can participate in RR and WA?

Both markets are open to participants that are parties to the Connection Use and System Code (CUSC), either as a Generator, Supplier or Virtual Lead Party. The CUSC and related documents can be found here. To find out further information on how to accede to the CUSC and associated costs, you can contact our Connections team.

Participants will also need to accede to the Balancing and Settlement Code (BSC) for which there are associated costs. You are also able to contact the Market Entry team at Elexon for further information.

Virtual Lead Parties

As part of P344 and GC0097, a new market participant type has been created, VLPs, who will be able to register Secondary BMUs for the provision of balancing services to the System Operator. We have previously hosted a webinar outlining what a VLP is, and the slides and a recording of that webinar can be found here.

Following the approval of CMP295, VLPs are now able to sign up to the CUSC as set out above.


As part of EBGL there is a requirement for providers to be prequalified before participating in certain markets. These markets are BM (including Wider Access), TERRE, STOR and Fast Reserve.

We have built a dedicated prequalification portal for VLPs wanting to prequalify Secondary BMUs for the BM and TERRE. For Primary and Additional BMUs wanting to prequalify for TERRE, please contact [email protected].

Further details on the steps to prequalify, can be found under the How to Participate tab. 

Elexon Guidance

Elexon have provided guidance on how to register units, including for VLPs, along with how TERRE will be settled.