APS Interconnection: Find Power, Navigate the Queue, Secure Your Site
Arizona Public Service (APS) operates outside an ISO and studies generators in one annual cluster opening April 1. Large loads connect as retail customers, though APS has reportedly paused new data center queue additions. Explore APS interconnection processes with our interactive guide, then see where capacity is available.
APS Interconnection at a glance
Quick facts | APS |
|---|---|
Who runs it | APS runs its own transmission system and balancing area in Arizona, and isn’t part of an ISO. It trades in CAISO’s Western Energy Imbalance Market and filed in October 2026 to join SPP’s Markets+. FERC approves its transmission tariff, and the Arizona Corporation Commission oversees retail service. |
Governing rules | APS’s transmission tariff: Attachment O for generators over 20 MW, and Attachment P for small generators |
Generator study process | One annual cluster, filed through APS’s PowerClerk portal: a 45-day window, a 75-day engagement window, a two-phase Cluster Study (90 days, then 75 days), a 90-day restudy if needed and a facilities study with a draft due in 90 days |
Current cluster | The 2026 cluster has 54 requests totaling about 24.8 GW, more than double the 2025 cluster, and was in Phase 1 as of October 13, 2026 |
Total queue | About 223 active requests totaling about 73.9 GW, including projects already in design, construction or service |
Next window | Opens April 1, 2027 and closes May 15 |
Generator costs | $305,000 at filing, at any size: a $100,000 study deposit, a $5,000 non-refundable fee and a $200,000 readiness deposit. The readiness deposit rises to 5% of upgrade costs after Phase 2 and 10% at the facilities study, with 20% total security at the interconnection agreement. |
Withdrawal penalties | None before the Cluster Study. After that, at least the study deposit, rising to 5% of upgrade costs during a restudy, 10% during the facilities study and 20% after signing. |
Small generators | Projects of 20 MW or less that join the cluster post the $100,000 study deposit, with no readiness deposit or withdrawal penalty |
How large loads connect | As APS retail customers, working with APS directly. APS has no published form, fee or size threshold for large loads. |
Large load queue status | APS has committed more than 4,000 MW to future data center customers and isn’t adding new projects to its data center queue, according to an October 2026 press report. Its stated route for new demand is a long-term contract that pays upfront for new supply. |
Large load rates | Data centers take service under APS’s Extra High Load Factor rate. APS’s pending rate case would raise it 45% and add minimum bills and collateral, with an ACC vote due by December 31, 2026. A 2026 state law also lets the ACC set contract terms for these customers. |
Last updated | November 3, 2026 |
APS Generator Interconnection Process
Generator interconnection,
step-by-step
APS studies generators in one annual cluster, with a 45-day window from April 1 to May 15. Its Cluster Study runs in two phases, with a decision point after each, and deposits rise as a project moves forward.
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Check the queue reports. APS posts its active and withdrawn queues, showing each request’s size, county, POI and study status.
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Apply during the April window. Submit through APS’s PowerClerk portal with $305,000 in deposits and fees, at least 90% site control and your choice of network or energy-only service.
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Customer engagement window. Over 75 days, APS holds a scoping meeting, each project settles its point of interconnection, and developers sign a Cluster Study Agreement.
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Phase 1 study. APS runs a power flow and voltage study of the cluster over 90 days. Developers then have 20 days to continue or withdraw.
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Phase 2 study. APS adds stability and short-circuit analysis over 75 days. To continue, developers re-show site control and raise their readiness deposit to 5% of upgrade costs.
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Restudy and facilities study. APS restudies the cluster if needed. Developers then show 100% site control and raise their deposit to 10%, and APS delivers a draft facilities study in 90 days.
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Sign the interconnection agreement. Developers post 20% of upgrade costs, meet a development milestone and sign the agreement. Delivering power requires a separate transmission request.
APS Large Load Interconnection Process
Large Load interconnection,
step-by-step
Large loads connect as APS retail customers with no public fee or size threshold. With 4,000+ MW already committed to future data centers, APS has reportedly paused new queue additions. Confirm current requirements with APS.
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Start with APS. A new data center works with APS directly, not through the generator queue.
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Retail or wholesale. A wholesale customer serving the load over APS’s grid adds it as network load under APS’s transmission tariff instead.
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Check for room in the queue. APS isn’t adding new projects to its data center queue for now, according to an October 2026 press report.
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Fund new supply. APS’s route for new demand is a long-term contract that pays upfront for the generation and transmission needed. APS has proposed a subscription model for a planned gas plant, with service likely in 2031 to 2033, according to press reports.
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Load study. APS studies the load’s effect on its generation, transmission and distribution, based on the customer’s load and ramp schedule.
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Sign a service agreement. Data centers take service under APS’s Extra High Load Factor rate. Its pending rate case and a 2026 state law could add minimum bills, collateral and contract terms.
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Energize in stages. APS has pledged to connect very large customers only as fast as it can serve them reliably, so ramps are likely staged.
What's changed recently in APS interconnection
Last updated November 2026
APS interest surged in 2026, with its generator cluster more than doubling and data center queue reportedly filling. New state rules and APS rate changes could also impact large loads, making it critical to confirm current requirements.
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April 1 – May 15, 2026: APS’s 2026 cluster window drew 54 requests totaling about 24.8 GW, more than double the 2025 cluster.
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May 18 – July 7, 2026: The ACC held hearings on APS’s rate case, which proposes a 45% increase in its rate for data centers, plus minimum bills and collateral.
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2026: A new Arizona law (ARS 40-207) lets the ACC set minimum bills, contract length, exit terms and collateral for new large customers like data centers.
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September 17, 2026: APS filed revisions to its generator interconnection agreements at FERC.
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October 9, 2026: APS had committed more than 4,000 MW to future data centers and stopped adding new projects to its data center queue, according to a press report.
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October 14, 2026: APS filed tariff changes at FERC to join SPP’s Markets+.
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Coming up: The recommended order in APS’s rate case, expected in late November; the ACC’s vote, due by December 31, 2026; and the next cluster window, opening April 1, 2027.
How LandGate Helps with APS Interconnection
APS’s 2026 cluster more than doubled as grid competition surged. With its data center queue reportedly full, new demand may require funding new generation and transmission. LandGate brings the data behind these decisions into one platform.
Get your projects on the grid faster with reliable transmission data.
Stand out in a crowded cluster
With about 24.8 GW in the 2026 cluster, the projects near your point of interconnection shape your results. Search parcels by criteria such as distance to a substation and available offtake capacity, and see available transfer capacity at transmission-level injection points to find sites with room to spare.
Know upgrade exposure risks
After Phase 2, staying in means raising your readiness deposit to 5% of upgrade costs. LandGate shows queued projects at the substation level, and its automated offtake capacity studies show substation details, capacity results, limiting elements such as transmission lines and transformers, and queue data.
Plan the supply and the site
If a data center will fund new generation & transmission to get service from APS, the site needs to work for both. LandGate shows ATC at transmission-level injection points for generators and offtake capacity for loads at those same points, and its Data Center Due Diligence reports rank substations by capacity.
Lock up the best properties
APS requires 90% site control at filing and 100% at the facilities study. LandGate pairs its comprehensive grid data with proprietary landowner leads, nationwide ownership data and contact details, and a map-based CRM to help you find, secure, and track the right parcels with the best infrastructure profile.
