The ISO interconnection game

The US electric grid is undergoing seismic transformation as developers race to connect new generation to regional transmission networks (RTNs) and meet a surge in demand for energy from data centres and power-hungry manufacturing facilities.  

This surge in demand, however, has overwhelmed the interconnection queues of the major independent system operators (ISOs), such as PJM, MISO, ERCOT, CAISO, NYISO and SPP. These queues, essentially waiting lines for projects seeking grid access, have become bottlenecks that not only risk interruptions to supply, but threaten to slow the pace of the energy transition even further. 

What is causing the interconnection queue backlog? 

A grid interconnection backlog occurs when proposed energy projects ‒ be they fossil-fuel based, solar, wind, hydro or other ‒ pile up faster than grid operators can study and approve them. Each project must undergo rigorous technical and economic analysis to ensure it will not destabilise the grid and get attributed the costs for network upgrades to accompany their interconnection. However, with a build up of speculative projects over time - many of which will not materialise - delays to queue processing are inevitable. Consequently, the ISOs and RTOs are undertaking reforms to streamline the interconnection process. 

Ambitious reform of the PJM interconnection queue 

PJM’s interconnection queue reform is among the most ambitious of the ISOs. In 2023, PJM transitioned from a ‘first-come, first-served’ model to a ‘first-ready, first-served’ approach to fend off developers who had bagged spots in multiple interconnection queues, hoping one would pay off. Its new approach prioritises projects that are more likely to be built, streamlining the PJM queue. 

Key elements of PJM’s reform include: 

• Fast-track processing: more than 26 GW of generation interconnection projects have been processed through an expedited track. 

• AI-enhanced planning: PJM has partnered with tech firms to deploy smart tools for interconnection queue management. 

• Surplus interconnection service: allows battery storage and other resources to utilise unused grid capacity. 

• Capacity interconnection rights transfer: simplifies the replacement of retiring facilities with new generation. 

Reducing dropouts in the MISO interconnection queue 

The MISO grid, which covers parts of the Midwest and South, faces similar challenges. MISO power demand has risen sharply, which has meant that the MISO interconnection queue now comprises hundreds of projects. The ISO has undertaken several reforms to reduce the number of projects that drop out mid-process: capping the number of projects entering the queue and interactive maps to help developers track interconnection progress. 

Explosive growth in the ERCOT interconnection queue 

There has been explosive growth in the ERCOT generation interconnection queue in Texas. As of May 2025, there were more than 2,000 interconnection requests in the ERCOT queue. The ERCOT grid is consequently grappling with capacity constraints and power reliability issues. The Texas ISO is also currently implementing reforms to reduce the grid queue, lower the dropout rate and increase transparency. 

Multi-track reform of the CAISO interconnection queue 

California’s CAISO interconnection queue is packed with solar and battery projects aimed at supporting the CAISO grid and meeting state power needs. CAISO has implemented a multi-track reform strategy in response to Federal Energy Regulatory Commission (FERC) Order No. 2023. It has overhauled the intake process for interconnection requests; it has introduced intra-cluster prioritisation to fast-track mature projects; and, in 2026, it will modify transmission deliverability allocation processes for the 2027 cycle. These grid reforms aim to reduce speculative projects, prioritise resource-rich zones aligned with California Public Utilities Commission planning, and improve study timelines and transparency. 

Digital solutions to the NYISO interconnection queue backlog 

New York’s NYISO queue is also congested, with capacity expansion plans slowed by interconnection delays. The NYISO queue is experiencing steady growth, driven by New York’s aggressive clean energy goals and increasing interest in battery storage and co-located renewable projects. Like CAISO, it’s investing in digital tools and stakeholder engagement to accelerate approvals. 

SPP, ISONE and AESO interconnection queue 

The SPP grid, serving parts of the central US, is facing significant pressure from a surge in renewable and battery storage proposals, prompting reforms and strategic planning updates. The ISONE queue and the AESO interconnection queue reflect similar trends in New England and Alberta, Canada, respectively. 

The road ahead: collaboration and innovation 

Solving the interconnection queue crisis requires coordinated action across ISOs and RTOs. Innovations such as grid-enhancing technologies, shared upgrade costs and better modelling of battery storage behaviour are being mandated by regulators such as the FERC. 

Unlock interconnection queue data and insights 

Understanding US connection queues is crucial for tracking capacity and assessing project processing times across markets. Grid capacity constraints and development opportunities require unparalleled visibility to make informed investment decisions. 

With interconnection queue data and insights, you can track project pipelines, assess market saturation, and identify emerging investment prospects across key regional transmission organisations. Our proprietary Lens Power & Renewables Americas tool provides this comprehensive view of the interconnection landscape. 

This means you can make faster, more confident investment decisions whilst reducing development risks and identifying the most promising opportunities before your competitors. Access to real-time queue data transforms how you evaluate market entry strategies and portfolio expansion plans.