Getting to grips with energy flexibility and storage

Matt Caville, Senior Advisor for Decarbonisation of Complex Sites at Energy Systems Catapult

As an energy manager in the public sector, you can help your sites benefit from the growing demand for energy flexibility. It’s a complex market worth joining, as it can bring in extra income and supports the government’s push for more clean power on the grid.

At Energy Systems Catapult, we’ve been funded by the Department for Energy Security and Net Zero (DESNZ) to produce a Flexibility and storage guide for public sector buildings. Here we discuss some of the key findings and practical insights that can help you start exploring the opportunities available to you.

What is flexibility?

Two decades ago, peaks and troughs in energy demand were simpler to manage. The National Grid control room responded by switching centralised power stations on and off. Now, with our increasing use of distributed and intermittent forms of cleaner energy, balancing the grid has become more of a challenge, and that’s where flexibility comes in. 

Flexibility allows buildings and the National Grid to accommodate fluctuations in renewable energy generation by storing excess generation when it is not needed, and releasing the energy when demand peaks or renewable generation is low.

Public sector organisations can provide this flexibility by installing energy generation and storage projects on their sites, and by signing up to flexibility services that avoid costs, generate revenue and decarbonise operations.

In February, we’re hosting the Innovating to Net Zero conference in Birmingham, where we’ll discuss how we can build flexibility into the energy system. We’d love to have you along. At the end of this article, you’ll find a link to register for the event and further resources to help you get started on flexibility.

Providing flexibility

As a flexibility provider you make temporary adjustments to how you consume, generate, or store electricity when requested, and get paid by flexibility procurers who purchase these services from you.

To find out more about the flexibility services needed in your local area, check out the Flexible Power initiative run by four of the UK’s distribution network operators. This handy interactive map helps you explore what’s on offer and how you can take part: www.flexiblepower.co.uk/ 

There is also the Piclo Flex platform providing an independent marketplace for flexibility services across the UK. You can search the competitions at: https://picloflex.com/

Can you participate?

The types of storage technologies, flexibility services and route-to-market that will be relevant to your site will depend on the type, size and context of your site. As a rough guideline, sites with around 500 kW of flexible capacity are typically considered viable for participation in flexibility markets.

• Medium buildings including those run by local authorities and government departments/agencies are likely suitable for energy storage technologies ranging from hundreds of kWs but typically less than 1 MW.
• Large buildings such as hospitals and schools could have space for hundreds of kWs to multiple MWs.
• Campus sites including prisons, hospitals, universities and Ministry of Defence sites could host multiple MWs.

Energy storage options

Our guide includes a detailed description of energy storage systems, how developed they are and whether they are suitable for installation at public sector sites.

Here is a condensed snapshot of some the technologies currently available:

Demand Side Response (DSR)

This is the practice of adjusting electricity consumption patterns in response to changes in electricity supply, demand or pricing signals. DSR allows an organisation to either avoid costs or generate revenue.

Public sector organisations can work with DSR service providers and aggregators to identify the flexibility potential of specific sites and facilitate their participation in DSR.

Some of the processes used at your sites that are applicable to DSR are outlined in the table below.

Participation can also create opportunities for new projects to increase generation capacity or add storage.

Routes to market

Flexibility service providers help sites and businesses access flexibility markets. Their offerings typically break down into:

• Software-as-a-service: a provider sells you controls software and access to a market platform to manage your assets and how you participate in flexibility markets. The service is typically charged as a monthly fixed fee related on a £/MW/year basis. This option potentially allows your site to keep more of the revenue it generates but it requires sector knowledge and resource to operate. Therefore, a third-party operated model is likely preferable for most public sector sites.
• Optimisation services: an optimiser controls your site’s assets and access to flexibility markets to maximise revenue from storage, generations and/or Demand Side Response. The optimiser will provide an operations team to manage this. A typical commercial model would be a revenue share, with a site likely to pay 20-30% of its revenue.
• Aggregators: a company acts as an intermediary between multiple asset owners and the flexibility market. An asset owner may use an aggregator to simplify participation in flexibility markets or because they do not qualify to trade directly in the market.

When forming your business case, you could highlight non-financial benefits beyond your buildings. Look at how your local community could also benefit from your organisation becoming a flexibility service provider.

Strategies for participation

When engaging with a flexibility service provider, they are likely to guide you through a three-stage process:

• Consultation: including a site survey to understand your requirements, operational parameters and revenue potential.
• Implementation: provider assesses the site for upgrades, installs controls for the site to actively respond to flexibility markets, and connects you to their control room.
• Operation: provider advises on the best operational strategy and uses their trading desk to maximise revenue from your assets.

In the guide, we describe various strategies that can help the public sector access the flexibility market. These include:

• Aggregation: by pooling resources from multiple smaller, distributed energy resources – and even neighbouring organisations – public sector organisations can aggregate assets. This includes rooftop solar, batteries, electric vehicle chargers and DSR programs to create a more diverse portfolio that increases the flexibility services you can provide.
• Time of use tariffs: a pricing plan designed to encourage energy users to consume electricity at times when it is available cheaply. This in turn supports the growth of a sustainable and flexible energy system combining renewable generation and storage.

Next steps

We hope this article prompts you to consider how the public sector assets and the sites you help manage could participate in flexibility.

At Energy Systems Catapult we believe that flexibility and storage will come to dominate energy conversations as we unlock ways to flatten the peaks in demand brought about by our increasingly clean energy system. On 25 February, we’re hosting our flagship Innovating to Net Zero conference in Birmingham, where we’ll explore the practical realities of building flexibility in the energy system, look at the questions keeping energy experts awake and spotlight the pioneers accelerating clean energy innovation.

Join other energy sector professionals, experts, policymakers, investors and tech developers by registering here (book your ticket using the code ENERGY2026 to get £50 off): https://bit.ly/ITNZ26

Download our Energy flexibility and storage guide and the associated annex on technologies here: https://bit.ly/flex-guides

This article appeared in the Jan/Feb 2026 issue of Energy Manager magazine. Subscribe here.