GB Capacity Market: Secured Capacity by Delivery Year
The Capacity Market pays generators, batteries, interconnectors and demand-side providers to be available when the electricity system is under stress. See what is secured for each delivery year.
What the Capacity Market is for
Providers win agreements through auctions and must deliver when a system stress notice is issued. They are paid for being available, not for the electricity they generate.
Main auctions run about four years ahead, with a top-up auction around one year ahead. Each delivery year is separate and must not be added to the others because multi-year agreements appear more than once.
What is secured, and when
The figures show live agreements by delivery year, technology and provider.
Great Britain · NESO Capacity Market register
49.3 GW is under contract for delivery year 2026/27 — the year running now
The Capacity Market pays generators, storage and demand-side response to be available when the electricity system is most stressed. These are availability obligations, not a record of electricity generated, and each delivery year is counted on its own.
Secured for 2026/27
49.3
GW of capacity obligation
Agreements in that year
994
held by 948 capacity market units
Largest year on record
54.5
GW in 2017/18
Register size
18,203
contract rows across 14 delivery years
What is holding those agreements in 2026/27
Shares are of that single delivery year's capacity obligation.
| Technology | Agreements | Obligation MW | Share |
|---|---|---|---|
| Gas | 340 | 30,263.6 | 61.4% |
| Interconnector | 10 | 6,854.4 | 13.9% |
| Nuclear | 10 | 4,597.5 | 9.3% |
| Battery storage | 190 | 1,800.5 | 3.7% |
| Pumped storage | 10 | 1,789.9 | 3.6% |
| Demand side response | 274 | 1,563.9 | 3.2% |
| Hydro | 36 | 829.6 | 1.7% |
| Energy from waste | 37 | 686.7 | 1.4% |
| Oil and diesel | 31 | 679.4 | 1.4% |
| Offshore wind | 3 | 105.1 | 0.2% |
| Onshore wind | 16 | 45.2 | 0.1% |
| Solar | 25 | 22.6 | <0.1% |
| Bioenergy | 2 | 18.6 | <0.1% |
| Other thermal generation | 8 | 0.0 | 0.0% |
| Storage (unspecified type) | 2 | 0.0 | 0.0% |
Connected to the transmission network
42.1 GW
Connected to a distribution network
7.1 GW
Secured capacity by delivery year
Each row is a separate delivery year. They are deliberately not added together: a multi-year agreement appears once in every year it covers.
| Delivery year | Agreements | Obligation MW | Relative size |
|---|---|---|---|
| 2016/17 | 54 | 762.2 | |
| 2017/18 | 431 | 54,503.4 | |
| 2018/19 | 520 | 51,474.2 | |
| 2019/20 | 484 | 48,094.3 | |
| 2020/21 | 622 | 50,138.4 | |
| 2021/22 | 570 | 46,874.1 | |
| 2022/23 | 635 | 47,048.1 | |
| 2023/24 | 748 | 47,841.1 | |
| 2024/25 | 774 | 47,415.7 | |
| 2025/26 | 988 | 49,614.7 | |
| 2026/27shown above | 994 | 49,257.0 | |
| 2027/28 | 520 | 41,887.6 | |
| 2028/29 | 666 | 43,040.3 | |
| 2029/30 | 691 | 40,108.6 |
Source: National Energy System Operator — Capacity Market Register — Capacity Market Unit (CMU). Great Britain Capacity Market applications and agreements. Licence: National Energy SO Open Data Licence v1.0. Supported by National Energy SO Open Data.
Why the megawatts look small: de-rating
De-rated capacity is the amount a unit can be relied on to provide during system stress. Conventional plants are discounted for outage risk; batteries are also discounted according to how long they can discharge.
This makes the totals smaller than nameplate capacity on the power stations page.
Who provides the capacity
The auction buys availability from several technologies.
- Gas plants can run for long periods and are lightly de-rated compared with storage.
- Batteries can respond quickly but are de-rated for limited duration.
- Demand-side response pays businesses to cut use when called.
- Interconnectors can import from neighbouring systems. Their capacity is on the interconnectors page.
What it costs, and who pays
Electricity suppliers fund capacity payments according to customer demand during winter peak hours and recover the cost through tariffs.
It is a smaller part of a typical bill than wholesale energy. The breakdown of the price cap shows the wider bill breakdown.
Frequently asked questions
What is the GB Capacity Market?
A scheme that pays generators, batteries, interconnectors and demand-side providers to be available at times of system stress, in return for a per-megawatt payment. It is a reliability mechanism rather than a subsidy for energy: providers are paid for standing ready, not for the electricity they produce.
What is a delivery year?
The twelve-month period an agreement covers, running from October to September. Auctions are held years in advance — a main auction four years ahead, so new build has time to be financed and constructed, and a top-up auction a year ahead to correct for what has changed since.
What does de-rated capacity mean?
The capacity a unit is credited with after allowing for how likely it is to be available and able to sustain output when the system is stressed. A gas plant is de-rated for the chance of breaking down; a battery is de-rated much harder because it can only discharge for a limited time. The de-rated figure, not the nameplate rating, is what the market buys.
Do I pay for the Capacity Market on my energy bill?
Yes, indirectly. The cost is levied on electricity suppliers in proportion to their customers’ demand during winter peak hours, and suppliers recover it through the tariffs they charge. It is a small component of a typical electricity bill compared with the wholesale cost of the energy itself.
Can batteries and demand-side response take part?
Yes, and both do. Batteries bid in on their de-rated capacity, which depends on how many hours they can discharge for. Demand-side response — businesses agreeing to reduce consumption when called — competes on the same footing, on the reasoning that a megawatt not used is worth the same as a megawatt generated.
