Rethinking curtailment predictions in renewable energy: a comparative study of the Ofgem-approved methodology and an alternative approach

The significant rise in distributed Renewable Energy Sources (RES) has led to grid congestion and the curtailment of generators and storage systems. To better utilise network assets and avoid costly network reinforcement, Distribution Network Operators (DNOs) have implemented Active Network Management (ANM) schemes that curtail generators during peak times. The financial viability of RES projects is heavily influenced by curtailment levels, necessitating robust predictive methodologies. As of April 2023, DNOs in Great Britain have adopted a new Ofgem-approved curtailment calculation methodology for the RIIO-ED2 price control period. This methodology, however, includes assumptions that likely overestimate future curtailment, such as the unrealistic year-round 100% export assumption for Battery Storage (BESS) systems, which typically export for only 2–4 hours daily. This paper compares the Ofgem-approved methodology with an alternative approach that incorporates realistic generation profiles, including meteorological data and linear programming for BESS operations. The findings suggest that the current methodology significantly overestimates curtailment, potentially threatening the financial viability of new low-carbon projects and posing a barrier to achieving Net Zero goals.