Demand Response
Short Term Operating Reserve (STOR)

Mitigate rising energy costs and reduce carbon emissions by responding to electrical stress events on the grid.

What is STOR?

Short Term Operating Reserve (STOR) is a reserve grid demand side response service that allows customers (service providers) to export energy that they generate themselves back to the grid to balance supply during times of peak demand or other unforeseen circumstances. The service is limited to specific times (availability windows) described in a service provider’s contract with the National Grid. The closer a service provider is to a high demand area (particularly in Wales or South East England), the more desirable they are.

How does STOR work?

Prospective providers submit prices for which they’re willing to provide the STOR services in a competitive tender process. These tender rounds are conducted three times each year. Smaller providers under 3MW may participate via an aggregator.

The service can be provided by both Balancing Mechanism (BM) and non-Balancing Mechanism service providers that operate in one of three ways:

  • Committed: Energy must be available at all times dictated by their contract.
  • Flexible: Only open to non-BM providers. It allows greater flexibility in terms of how many hours energy must be provided.
  • Premium Flexible: Similar to Flexible but with a greater guarantee of acceptance from the National Grid.

Service providers must be able to: 

  • Offer a minimum of 3MW generation or steady demand reduction.
  • Ensure response time for delivery within 240 minutes following instructions from the National Grid.
  • Sustain continuous delivery of energy for a minimum of 120 minutes.
  • Have a recovery period of no longer than 1200 minutes.
  • Deliver energy to the grid at least three times per week.


Providers are paid in one of two ways:

  • Availability: the provider is paid (£/MW/h) for the periods during which they make themselves available within the availability window.
  • Utilisation: the provider is paid (£/MW/h) according to the volume of energy delivered when instructed to deliver by the National Grid.

How can we help?

If you're interested in finding out more about becoming a STOR provider to help balance out the National Grid during times of high demand and cut energy costs, please get in touch with our team today.