Getting Ahead of CAISO’s 2026 Deliverability Window

In CAISO’s next cluster cycle, available Transmission Plan Deliverability (TPD) will determine whether projects are admitted into Cluster 16, making early visibility into TPD one of the most consequential factors in project siting today. CAISO recently confirmed that its constraint mapping spreadsheet - the dataset used to understand where Transmission Plan Deliverability (TPD) is available - will be released in mid-July 2026.

That means developers preparing for Cluster 16 (QC16) will have only a short window to ensure their projects are at POI's with capacity available, finalize site control, and submit interconnection requests before October.

How This Fits Into CAISO’s Process

Ahead of the spreadsheet release, CAISO plans to share an interim heatmap to give stakeholders early, high-level visibility estimate into deliverability conditions. However, it does not include the modeled allocation logic that ultimately determines where TPD is likely to be awarded. Without early visibility into constraint data, developers often rely on legacy assumptions or generic maps that don’t reflect the realities of the current study cycle.

To understand the importance of this data, it helps to look at how it shaped Queue Cluster 15 (QC15). During QC15, CAISO received 541 project submissions, which reduced to only 255 projects following procedural updates and a required resubmission based on new study requirements.

Given the large number of submissions, CAISO introduced a new intake process to help manage queue volume and focus study resources on the most feasible projects. As part of that process, CAISO conducted a system-wide assessment to determine available TPD as of August 2024, and published the results in the Constraint Mapping workbook. The dataset became a critical reference point for developers: it identified which areas of the grid had sufficient deliverability to support new interconnections. Projects proposing points of interconnection where TPD was already fully allocated would be removed from the queue.

In the end, 177 projects were admitted into QC15—about 33% of the original 541, or 69% of those resubmitted—representing a more focused study cohort aligned with available deliverability.

The next version of the Constraint Mapping workbook, which will inform the upcoming queue cycle, is expected to be released in July 2026. Because this data plays such a decisive role in project eligibility, developers are eager for early insight into where deliverability capacity may exist as they prepare for the next intake window.

Nira’s Early-Stage TPD Estimates

To bridge that information gap, Nira is releasing CAISO TPD estimates this month, using the most up-to-date public data and study results available. These results will continue to be updated as active queue cycles evolve, as well as when CAISO publishes 2025-2026 TPP network upgrades.

Nira’s approach mirrors CAISO’s deliverability allocation framework, producing a proxy for where TPD is likely to be available when the next allocation window opens.

“Being able to replicate CAISO’s allocation logic with any fidelity is rare,” said Jared Vochoska, Transmission Planning Engineer at Nira. “Typically, only a handful of consultants working closely with the ISO understand the methodology at that level. Our goal is to make that level of insight accessible to every developer.”

With Nira’s estimates, developers can:

• Identify promising areas months before official data drops.

• Prioritize sites more likely to receive deliverability.

• Use ISO-aligned modeling to inform early siting and queue strategy.

Nira’s CAISO product launches at the end of October. Developers can request early access to preview the data and explore where opportunities may exist ahead of the 2026 deliverability cycle.