​Qualified capacity for the 2029/30 T-4 Capacity Market auction is confirmed, with bidding set to begin on the 10th of March. At 45.2 GW against a 39.4 GW target, this is the most oversupplied T-4 in years, pointing to a clearing price below below the ~£60/kW/yr seen in recent auctions

Gas makes up 25.8 GW of the de-rated capacity, with 55% entering as refurbishing capacity following the lowering of capex thresholds. The surplus pushes prices down, but this volume of refurbishing gas now holds price-maker status, creating a competing upward force.

Battery storage enters with a record 9.5 GW of connection capacity and 3.0 GW de-rated.

Missed our T-1 article? Read our analysis of what qualified capacity tells us about the 2026/27 T-1 auction.

Excess qualified capacity points to a lower clearing price

Across past T-4 auctions, the relationship between excess qualified capacity and clearing price has been consistent: larger surpluses produce lower clearing prices.

The three most recent rounds had the tightest supply-demand balances since the Capacity Market began, with excess capacity ranging from -0.7 to 3.0 GW. All three cleared at or above £60/kW/yr.

This year's auction has significantly more surplus, suggesting that run is over.