Interconnection queue guide · CAISO
CAISO interconnection queue
How the cluster study process and intake scoring work, when the next application window opens, and what the public queue record shows at individual points of interconnection.
GridVision AI ResearchPublished Updated
CAISO at a glance
- Process
- A Cluster Study Process under CAISO's Resource Interconnection Standards. Projects under 5 MW can use a Fast Track path at any time of year.
- Intake reforms
- Interconnection Process Enhancements 2023 took effect on October 1, 2024. Projects are scored on commercial interest, project viability and system need, and CAISO can study projects up to 150% of available transmission capacity.
- Cluster 15 intake
- CAISO reported that scoring and filtering reduced Cluster 15 from 541 applications (347 GW) to 145 applications (approximately 68 GW), which received initial study results in November 2025.
- Cluster 16 application window
- The tariff sets an annual window from October 1 to October 15 beginning in 2026. CAISO's portal opened for preparing applications on September 4, 2026, with submissions blocked until October 1, 2026.
- Latest rule change
- FERC accepted Interconnection Process Enhancements 5.0 in part on August 4, 2026, effective August 5, 2026.
- Queue size
- CAISO's July 2025 board briefing put active projects from Cluster 14 and earlier at about 185 GW.
Sources: CAISO, Interconnection request and study; CAISO news release, “FERC approves ISO interconnection reforms,” October 1, 2024; CAISO Energy Matters, “2025 Year in Review,” December 4, 2025; CAISO tariff Appendix KK, Resource Interconnection Standards (as of June 25, 2025); CAISO notice, GRIP portal available for Cluster 16 applications, September 4, 2026; FERC order on CAISO Interconnection Process Enhancements 5.0, August 4, 2026; CAISO board briefing on interconnection process enhancements and the queue, July 2025.
Facts checked September 16, 2026.
How the CAISO process works
CAISO's tariff (Appendix KK) sets out the cluster sequence and its target durations:
- 01Cluster application windowA 15-day window, October 1–15 each year from 2026.
- 02Customer engagement windowA 90-calendar-day period.
- 03Cluster studyTargeted for completion 150 calendar days after the customer engagement window closes. A reassessment is performed before each cluster study.
- 04Interconnection facilities study120 days planned.
- 05Transmission plan deliverability allocation
- 06Generator interconnection agreement
Intake scoring and zonal study limits from Interconnection Process Enhancements apply to Cluster 15 and later clusters. The current tariff governs any live project.
Sources: CAISO tariff Appendix KK, Resource Interconnection Standards (as of June 25, 2025); CAISO news release, “FERC approves ISO interconnection reforms,” October 1, 2024.
What the public record shows at CAISO points of interconnection
Across the 10 CAISO points of interconnection GridVision has published so far, the Berkeley Lab dataset records 118 interconnection requests filed between 1999 and 2023.
| Outcome | Requests | Capacity (MW) |
|---|---|---|
| Reached commercial operation | 25 | 5,098 |
| Withdrew | 64 | 15,913 |
| Still active | 29 | 7,211 |
| Total | 118 | 28,222 |
For the requests that were built, the median time from request to commercial operation was 8.0 years. For those that withdrew, the median time from request to withdrawal was 1.0 years.
These 10 nodes are not a random sample of CAISO, and a pattern at one point of interconnection does not transfer to another. The dataset records what happened, not why.
| Point of interconnection | State | Requests | Built | Withdrawn | Active |
|---|---|---|---|---|---|
| Hoodoo Wash Switchyard 500 kV | Arizona | 13 | 2 | 5 | 6 |
| Colorado River Substation 230 kV | California | 16 | 3 | 11 | 2 |
| Devers Substation 230 kV | California | 8 | 1 | 6 | 1 |
| Gates Substation 230 kV | California | 7 | 1 | 6 | 0 |
| Kramer Substation 230 kV | California | 9 | 1 | 3 | 5 |
| Otay Mesa Switchyard 230 kV | California | 14 | 6 | 5 | 3 |
| Stroud switching station 70 kV | California | 6 | 1 | 5 | 0 |
| Victor Substation 230 kV | California | 6 | 1 | 5 | 0 |
| Whirlwind Substation 230 kV | California | 23 | 6 | 10 | 7 |
| Windhub Substation 230 kV | California | 16 | 3 | 8 | 5 |
Questions to answer before advancing a CAISO queue position
- Is the project headed for a Deliverable Zone or a Merchant Zone, and what evidence supports the intake score you expect?
- Does the project need a transmission plan deliverability allocation, and what is the plan if it does not receive one?
- Which reassessment results could change your cost responsibility before the next financial commitment?
- Which unknowns could change the answer, who owns each one, and when will it be resolved?
Related reading
Weighing whether to advance a CAISO queue position?
Bring the decision, and get back a management-ready decision record: what is verified, what is assumed, what is still unknown, and what to do next.
Bring One Live DecisionSources
- CAISO, Interconnection request and study
- CAISO news release, “FERC approves ISO interconnection reforms,” October 1, 2024
- CAISO tariff Appendix KK, Resource Interconnection Standards (as of June 25, 2025)
- CAISO notice, GRIP portal available for Cluster 16 applications, September 4, 2026
- CAISO Energy Matters, “2025 Year in Review,” December 4, 2025
- CAISO board briefing on interconnection process enhancements and the queue, July 2025
- FERC order on CAISO Interconnection Process Enhancements 5.0, August 4, 2026
- Lawrence Berkeley National Laboratory, Queued Up: 2026 Edition (CC BY 4.0)
Facts checked September 16, 2026. Process rules and queue data change; the governing tariff, manuals and study documents control any live project.