Independent System Operators (ISOs) and regional grid operators are entering summer 2026 with a clear expectation: demand growth is accelerating faster than the resource mix is stabilizing. Across major markets, load expansion is being driven by large, concentrated data center development, broad electrification trends, and intensifying heatwaves. While operators broadly expect to maintain reliability, planning assumptions increasingly rely on narrower reserve margins and more active system management, signaling a shift away from historically comfortable supply cushions.
Western Interconnection: Rapid Load Growth Meets Intermittent Supply
In the Western Interconnection (WECC), this dynamic is especially pronounced. Demand is forecast to climb significantly over the next decade, with 2026 marking the early stages of that surge. Regions like Arizona are already seeing meaningful year-over-year growth, largely tied to data center expansion. The challenge is not simply the scale of demand, but the composition of supply — where a growing share of incremental capacity is intermittent and weather-dependent. This introduces greater variability into net load profiles and increases the need for flexible resources and balancing mechanisms during peak conditions.
ERCOT: Large Load Expansion Drives Price and Reliability Risk
In ERCOT, tightening supply-demand conditions are expected to translate directly into market impacts. Forecasts point to higher wholesale power prices during summer peaks, particularly in stress hours when demand spikes and reserve margins compress. ERCOT currently has over 400 GWs of large-load interconnection requests, which is more than four times the all-time peak demand of 85.5 GWs. These requests are for oil & gas, industrial facilities and crypto mining as well data centers, which make up approximately 75% of the requests. Many of these individual requests exceed 75 MW, while some requests exceed 1 GW or 1,000 MWs in demand. This is not incremental demand, but step-change expansion that requires substantial infrastructure, generation, and transmission investment to maintain system reliability.
ISO New England: Evolving Load Shapes and the Duck Curve Challenge
In ISO New England, overall peak demand remains relatively stable in the near term, but underlying load shapes are evolving. The increasing penetration of distributed solar is deepening the “duck curve,” with lower midday net load and steeper evening ramps. Reliability is becoming more dependent on behind-the-meter resources and energy storage to manage these intra-day swings. At the same time, longer-term projections suggest winter peaks may ultimately surpass summer demand, reflecting the growing impact of electrified heating.
Great Britain: Import Reliance and Operational Complexity Increase
Meanwhile, Great Britain is preparing for a different kind of challenge. While total supply is expected to be sufficient, the system is likely to rely more heavily on electricity imports during peak periods, particularly via interconnections with Continental Europe. Operators are also anticipating more frequent interventions to maintain system stability during low-demand periods, highlighting the operational complexity introduced by high renewable penetration and evolving demand patterns.
What’s Driving the Surge: Data Centers, Electrification, and Heat
Across all regions, common drivers are converging: rapid data center expansion, sustained cooling demand, and increasingly volatile weather patterns. These forces are not cyclical; they represent structural changes in how and when electricity is consumed, placing sustained pressure on peak capacity requirements.
From Capacity to Flexibility: How ISOs Are Managing Risk
In response, ISOs are advancing probabilistic resource adequacy frameworks and expanding demand response programs to better manage uncertainty. The focus is shifting from simply ensuring enough installed capacity to ensuring the right mix of flexible, dispatchable, responsive resources that can perform under a wider range of operating conditions.
Implications for Energy Buyers and Market Participants
For energy market participants, the implication is clear — summer reliability is no longer just a function of installed capacity, but of flexibility, timing, and the ability to respond dynamically to rapidly changing system conditions. Procurement strategies, risk management approaches, and load flexibility will play an increasingly central role in navigating this new market environment.