Executive Summary

• The T-1 2025/26 Capacity Market auction has 9.8 GW of prequalified de-rated capacity, exceeding the 6.5 GW target by 3.3 GW—the highest excess in five years.
• Batteries saw their highest-ever prequalified de-rated capacity in a T-1 auction, following a 20% increase in de-rating factors from NESO’s updated methodology.
• Two-hour battery energy storage systems dominate prequalification.

Subscribers to Modo Energy’s Research will also find out:

• How record-high nuclear prequalification could impact the auction’s final clearing price.
• How excess prequalified capacity could impact clearing prices.
• What to expect from February’s auction updates, including final capacity confirmations and potential bidding strategies.

To get full access to Modo Energy’s Research, book a call with a member of the team today.

Introduction

On 11 December 2024, the Electricity Market Reform (EMR) Delivery Body published the first Capacity Market Register for the T-1 2025/26. The register includes the details of all the units that prequalified, opted out, or were rejected ahead of the latest auction.

With prices in the T-1 Capacity Market falling since the 2022/23 delivery year, what could these early results indicate about this auction’s clearing price?

9.8 GW of de-rated capacity has pre-qualified for the 2025/26 T-1 Capacity Market auction