Prequalification results for the T-4 and T-1 Capacity Market auctions have been released, with battery storage rising significantly in both.

The T-4 auction for delivery year 2025/26 saw 8.3GW of battery storage registered – although after derating this drops to around 2.3GW – according to data released by EnAppSys.

Aurora Energy Research’s research associate Asgeir Fridrik Heimisson wrote on social media site LinkedIn that the 8.3GW figure is “significantly up from last year’s auction when almost 2GW pre-qualified”, adding that the increase was driven by one hour duration batteries.

In total, 50,850MW (~42,240MW derated) of capacity pre-qualified for the T-4 auction, EnAppSys said, with ~16,500MW (10,800MW derated) conditionally prequalifying. The auction has a target of 42,100MW of de-rated capacity.

This is compared to a target of 40.1GW last year, with 63,334MW pre-qualifying and 139MW conditionally pre-qualifying. This auction – for delivery year 2024/25 – cleared at £18//kW/year, a small jump from the previous year’s T-4 auction, which cleared at £15.97/kW/year.

The 2024/25 T-4 auction also saw a rise in battery storage capacity, which doubled from the 117.0237MW awarded contracts in the 2023/24 auction to 251.98MW.

For 2025/26, gas-fired capacity makes up the greatest component of likely capacity in the auction at 36GW of de-rated capacity, EnAppSys said, with this followed by interconnectors (7GW).

Renewables saw similar amounts of pre-qualified capacity compared to last year’s auction. Onshore wind saw 214MW pre-qualify, with 184MW conditionally pre-qualifying, compared to 403MW that pre-qualified last year. Meanwhile, 16MW of solar pre-qualified and 275MW conditionally pre-qualified, compared to 115MW that pre-qualified last year. 924MW of hydro capacity pre-qualified, an increase on last year’s 803MW.

Sizewell B1 and Sizewell B2 were the only nuclear units to pre-qualify, with every other nuclear unit opting out of the auction, resulting in a total capacity of 1,231MW.

T-1 pre-qualification results

The EMR Delivery Body also released the pre-qualification results for the T-1 auction for delivery year 2022/23, with 5,974MW (4,600MW derated) of capacity prequalifying.

A further 1,355MW (900MW derated) conditionally pre-qualified, with a target of 4,500MW of derated capacity, according to EnAppSys.

Like the T-4 auction, gas-fired generation dominated, with 3,607MW compared to 1,240MW last year.

Coal also pre-qualified, with Ratcliffe-on-Soar 4 contributing 513MW of capacity.

Battery storage saw the second highest amount of capacity pre-qualify, with 1,021MW compared to 482MW in the previous auction. This corresponds to 599MW of derated capacity.

DSR units and batteries both had more conditionally pre-qualified capacity than gas in this auction, with 584MW and 523MW respectively against 248MW for gas units. Batteries did, however, have 154MW of rejected capacity, more than any other fuel type.

Renewables, meanwhile, saw decreases in pre-qualified capacity compared to last year, with 149MW of onshore wind capacity pre-qualifying compared to 170MW last year. 43MW of solar capacity prequalified against 75MW last year, while 28MW of hydro capacity prequalified against 82MW from last year.

Last year’s T-1 auction for 2021/22 cleared at a record high price of £45/kW/year on day one, with this following on from record low prices of just £0.77/kW for the 2019/20 winter period.

The T-1 auction for 2020/21 also saw low prices, clearing at £1.00/kW/y.