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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.

29 January - We have published an update to our letter from 19 December on the future of STOR tenders.
For any queries you may have, please contact your account manager or a member of the team at [email protected]

23 January - We have published documents relating to the webinar held on 8 January on the process for transferring STOR contracts. These can be found under the Technical Requirements tab under the PAS Documents heading.

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.

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.