PJM IPS 12.18.25: Winter Reliability and Planning Model Updates

January 5, 2026

PJM IPS 12.18.25: Winter Reliability and Planning Model Updates

The PJM Planning Stakeholder (IPS) meeting on December 18 served as a year-end checkpoint on planning assumptions heading into the 2026 Regional Transmission Expansion Plan (RTEP) cycle. The agenda reflected the increasing complexity PJM faces as it balances near-term winter reliability risks with longer-term structural changes in load, resource mix, and interconnection dynamics. Discussions covered winter reliability drivers, refinements to planning models, long-term scenario development, and persistent interconnection queue and affected-system challenges.

Across these topics, a consistent theme emerged: PJM’s planning framework is being pushed to accommodate greater uncertainty, both in how load materializes and in how resources perform under increasingly stressed system conditions.

Winter Reliability and Load Uncertainty

PJM opened the meeting with discussion of winter reliability conditions, focusing on several drivers that continue to shape both operational readiness and planning stress cases. Stakeholders highlighted the growing prevalence of large, flat-profile loads, particularly data centers and industrial facilities, that do not exhibit traditional weather-driven variability. Unlike residential or commercial demand, these loads can remain elevated during extreme cold events, reducing the system’s ability to rely on demand diversity as a mitigating factor.

Gas supply constraints were also emphasized as a persistent winter reliability risk. PJM noted that while generator availability assumptions have evolved since Winter Storm Elliott, uncertainty remains around fuel deliverability during prolonged cold periods. Pipeline congestion, contractual limitations, and competing residential heating demand all complicate planning assumptions for gas-fired generation, which continues to serve as a critical reliability resource during winter peaks.

Stakeholders stressed that extreme-weather events are no longer outliers but are increasingly informing long-term planning criteria. As a result, winter stress cases are becoming more prominent in planning discussions, influencing both resource adequacy assumptions and transmission needs. PJM acknowledged that balancing realistic stress testing with planning conservatism remains an ongoing challenge.

Load Forecast and Planning Modeling Updates

IPS reviewed refinements to PJM’s load forecasting and resource modeling methodologies, with particular attention to how emerging load types and new resources are incorporated into planning models. PJM discussed updated treatment of phased large loads, emphasizing the need to better align forecasted demand with realistic construction and energization timelines.

Stakeholders raised concerns about transparency and consistency in how large loads are represented across different planning studies, including RTEP base cases, sensitivity analyses, and long-term scenarios. Questions centered on how PJM determines when phased load increments are included, how uncertainty is reflected, and how assumptions are communicated to market participants.

On the resource side, PJM discussed ongoing adjustments related to inverter-based resource growth, including solar, wind, and battery storage. As the resource mix shifts, planning models must increasingly account for non-synchronous behavior, different availability profiles, and evolving reliability contributions. PJM reiterated that queue inclusion criteria remain a key control mechanism, but acknowledged stakeholder concern that assumptions about which projects “count” materially affect planning outcomes.

Long-Term Planning Scenarios

A significant portion of the discussion focused on PJM’s development of long-term planning scenarios for 2035 and 2040. These scenarios are intended to capture a range of potential futures, incorporating electrification trends, policy-driven resource shifts, and broader economic and technological drivers.

PJM outlined how electrification of transportation, buildings, and industrial processes is expected to materially increase load over the next two decades, though the pace and geographic distribution remain uncertain. Policy considerations—such as state renewable portfolio standards and emissions targets—are also shaping assumptions about resource retirements and additions.

Stakeholders noted that long-term scenarios are increasingly driving transmission needs that cannot be justified solely through near-term congestion or reliability metrics. Multi-driver projects that address load growth, resource integration, and resilience simultaneously are becoming more common, raising questions about cost allocation, prioritization, and stakeholder engagement. PJM emphasized that scenario development remains iterative and that stakeholder input will continue to play a critical role in refining assumptions.

Queue and Affected-System Coordination

Interconnection queue challenges remained a focal point of the meeting. PJM acknowledged that delays tied to affected-system studies, data quality issues, and coordination across neighboring regions continue to pose material risks to both project timelines and planning accuracy.

Stakeholders expressed concern that prolonged queue timelines complicate planning by increasing uncertainty around which projects will ultimately be built and when. Affected-system impacts, in particular, can introduce cascading delays that extend beyond PJM’s direct control. PJM outlined incremental process improvements aimed at improving coordination and communication, while acknowledging that structural challenges persist.

The discussion reinforced that queue health and planning accuracy are tightly linked. Poor modeling inputs, inconsistent assumptions, or delayed studies not only affect individual projects but also ripple through RTEP outcomes and long-term transmission plans.

What This Means for Market Participants

The December IPS meeting highlighted that PJM’s planning environment is becoming more interdependent and assumption-driven. Winter reliability risks, load uncertainty, evolving resource characteristics, and queue dependencies all interact to shape transmission outcomes. For developers, utilities, and large load customers, understanding how these assumptions are applied—and how they may change—has become increasingly important.

Success in PJM now depends not only on project merit, but on alignment with planning models, scenario frameworks, and queue processes that continue to evolve under growing system stress.

Zero Emission Grid helps stakeholders navigate PJM’s planning assumptions and interconnection dependencies by translating IPS discussions into actionable strategy. From evaluating how load and resource assumptions may affect RTEP outcomes to assessing queue risk and affected-system exposure, ZEG supports informed decision-making in an increasingly complex PJM planning landscape. Contact us today to get started.