08 Jul 2021
Alex Done

DA STOR - June 2021 Market Update

At a glance


  • An uptick of 43% in average clearing price from May to June, with more instances of high (>£5/MW/h) clearing prices than the previous month.
  • Day-to-day price volatility remains from May, with price swings driven by National Grid Electricity System Operator’s (NG ESO) strict aversion to overholding Short Term Operating Reserve (STOR) capacity.


  • Procured volumes remain constant at 1312 MW (avg.), in line with NG ESO's procurement targets – note this excludes 400 MW of firm long-term STOR contracts enduring to 2025.
  • Gas reciprocating engines were the dominant technology in day-ahead Short Term Operating Reserve (DA STOR) during July, accounting for 39% of firm STOR capacity. Pumped storage saw an increased share of awarded contracts, up 5% from May.

Service cost

  • Total service cost to NG ESO for DA STOR availability was £1.4m. This increased in line with the average clearing price, with contracted volume remaining constant.

Market share

  • Centrica secured the highest revenues from DA STOR, taking 18% of the total revenue with their 245 MW site in Peterborough, which secured contracts every day in June.
  • Individual site revenues across June ranged from £1075/MW to £42/MW, driven largely by the number of contracted days.

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