Short-term operating reserve (STOR)

At certain times of the day we may need access to sources of extra power to help manage actual demand on the system being greater than forecast or unforeseen generation unavailability.

19 December - We have published a letter regarding the suspension of the January STOR tender round (TR40).
We will be hosting a webinar on 8 January at 2pm, details of which are set out below, where we will provide more detail as well as answers to any queries you may have.


Join via Webex 

Join by phone: +44-20-7108-6317 Access code: 593 568 721

10 December - We have published Issue 12 of the STOR Standard Contract Terms. These terms will take effect from 18 December, with specific aspects taking effect from later dates as set out on the front page.

15 November - We have today published our Decision to Implement outlining a summary of responses received to the recent consultation along with our decision on which changes to take forward.

1 October 2019 - We have today published an Outline Change Proposal to set out various amendments to the STOR SCTs as a result of requirements under the Electricity Balancing Guidelines (EBGL) and System Operator Guidelines (SOGL), as well as the implementation of the new Non-BM despatch system and general housekeeping. Alongside the OCP document, we have published a draft of the proposed new terms as well as a proforma to submit responses.
Views on this consultation, must be submitted by 5pm on 1st November to [email protected] and marked with a subject of "STOR OCP-10 2019 Response [Company Name]

We have published documents on the new PAS project that we are developing to provide a new dispatch system for Non-BM STOR. These can be found under the Technical Requirements tab under the PAS Documents heading.

Where it is economic to do so, we will procure sources of extra power ahead of time through the STOR service. Providers of the service help to meet the reserve requirement either by providing additional generation or demand reduction.

The requirement for STOR varies depending on time of year, week and day.

Providing STOR

Both Balancing Mechanism (BM) and non-BM participants with a connection to either the electricity transmission or distribution network are able to provide STOR.

The service is open to any technology with the ability to increase generation or reduce demand by at least 3 MW.

Current STOR providers are located throughout Britain, although providers closer to high demand areas, including south east England and Wales, are more desirable.

Service dispatch

There are particular times of the day when the STOR service is more likely to be required. These are known as ‘availability windows’.

Providers are required to be available to operate at their contracted volume during these windows.

Availability windows

Typically, the service is used over two pre-defined windows:

  • morning window; and
  • evening peak window.

STOR may be required outside of these times.

STOR dispatch

BM providers will be dispatched through the Balancing Mechanism, while non-BM participants will be instructed and metered through STOR Dispatch (SRD PC). 

The installation of STOR dispatch is undertaken by external parties and takes six months to complete.