MISO PAC 10/08/25: MTEP25, Interconnection Process Reform, and IBR Modeling Enhancements

The MISO PAC held on 10/08/25 centered around topics of MTEP25, interconnection process reform, and IBR modeling enhancements. MISO emphasized that planning processes must evolve alongside market dynamics, integrating renewable resources efficiently while maintaining grid stability and flexibility. Below is a brief overview of key topics and discussions from the meeting.

MTEP25 Transmission Expansion Overview

A central discussion topic was the draft MISO Transmission Expansion Plan (MTEP25). The upcoming plan focuses on addressing rising demand, increasing renewable penetration, and replacing aging grid infrastructure. Key highlights included:

• More than 1,900 miles of new or upgraded transmission lines are identified in the draft MTEP25, emphasizing reliability and congestion relief.
• The plan incorporates roughly 11 GW of new large-load additions, including data centers and industrial facilities, which are reshaping regional power flows.
• About 70 % of Appendix A projects are scheduled for completion within three years, reflecting a push toward near-term implementation of critical upgrades.
• Stakeholder feedback from utilities, developers, and state agencies continues to guide project prioritization, ensuring that investments address both reliability and future renewable integration needs.

For developers and investors, MTEP25 signals that transmission expansion is not just a regulatory requirement—it’s a competitive advantage. Projects aligned with high-priority corridors and zones identified in the plan will have faster pathways to interconnection and delivery capacity.

Interconnection Process Reform

The PAC also discussed ongoing interconnection process reforms, a key focus for developers navigating MISO’s increasingly complex queue. The reform seeks to streamline interconnection requests, enhance queue discipline, and improve study efficiency. Important updates included:

• First-ready, first-served clusters: Cluster 1 studies are nearing completion, while Cluster 2 preparations are underway with standardized milestones and data templates.
• Faster model validation: Applicants must provide verified project data and accurate system models early in the process to reduce re-studies and bottlenecks.
• Cost allocation refinement: MISO continues to adjust cost-sharing methodologies to more fairly distribute upgrade expenses among interconnecting projects.
• Surplus and replacement requests: Proposed updates to the business practices manual (BPM-015) aim to clarify procedures for surplus capacity usage and resource replacement, minimizing administrative delays.

For renewable and storage developers, these reforms mean earlier readiness is essential. Projects that submit high-quality data packages and maintain milestone compliance will benefit from reduced queue times and more predictable study outcomes.

IBR Modeling Enhancements

Another major technical topic covered during the meeting was the expanded modeling requirements for inverter-based resources, such as solar PV, wind, and hybrid battery systems. MISO is enhancing its dynamic modeling and validation requirements to improve reliability performance and ensure accurate system studies. Key points included:

• IBR Model Submissions: Developers will soon be required to provide detailed dynamic models during interconnection applications, including validated parameters and control settings.
• Testing Protocols: MISO is implementing standardized performance tests to confirm model fidelity and system-level response.
• Implementation Timeline: The new modeling standards are expected to take effect in mid-2026, applying to new interconnection requests only.
• Grid Impact: Improved modeling will allow MISO to simulate system conditions more accurately, preventing voltage and frequency stability issues as renewable penetration grows.

This initiative is part of a broader national effort to ensure that renewable and inverter-based assets perform consistently under real-world disturbances—strengthening resilience and reducing event risk.

Large Load Growth and Regional Coordination

MISO continues to experience significant large load growth, especially from data centers, manufacturing expansions, and electrification projects. The PAC emphasized that managing these new demands requires close coordination between interconnection planning and regional transmission upgrades.

Additionally, MISO is expanding its coordination with neighboring grid operators to enhance interregional planning. Improved transfer capability and joint studies are essential to support reliability and efficient power flows between regions. For developers, this interregional collaboration could open new opportunities for cross-boundary renewable exports, but it will also require more sophisticated deliverability assessments and modelling consistency.

Key Takeaways for Stakeholders

By the close of the October 2025 PAC meeting, several clear messages emerged for stakeholders across the MISO footprint:

1. Align with MTEP25 priorities. Projects in zones with upcoming reliability upgrades or load-growth infrastructure will have stronger transmission support.
2. Prepare for stricter modeling standards. IBR modeling and validation will soon become a prerequisite for queue acceptance and performance compliance.
3. Engage early in Cluster 2. Queue discipline and milestone enforcement mean readiness and accuracy are more critical than ever.
4. Consider interregional dynamics. Transmission constraints and coordination with PJM, SPP, and other RTOs will shape future deliverability and congestion pricing.

MISO’s evolving planning landscape underscores that proactive engagement—not reactive compliance—is now the key to successful grid participation.

At ZEG, we help developers, investors, and asset owners navigate the complex terrain of MISO interconnection, transmission planning, and grid compliance. Whether you’re preparing for Cluster 2 participation, evaluating MTEP25 implications, or optimizing project models for IBR readiness, our team can guide you through each step.

ZEG’s expertise bridges the gap between technical grid analysis and strategic market positioning, ensuring your renewable or large-load project is not only compliant, but also competitive. Contact ZEG today to schedule a consultation and ensure your project portfolio is aligned with MISO’s latest transmission, deliverability, and interconnection reforms.

View Meeting Materials here.