What the queue actually is
Every generator or storage resource that wants to connect to the transmission or distribution system needs a formal agreement with the entity that operates it. The interconnection queue is the pipeline of pending requests for those agreements. In organized markets the ISO or RTO runs it (PJM, MISO, ERCOT, CAISO, NYISO, ISO-NE, SPP). Elsewhere, and for distribution-level projects, the local utility runs its own process.
Position matters because the cost of connecting depends on what else is assumed to be on the system when your project is studied. Under the older serial approach, each request was studied in filing order and every earlier project was treated as built. A project behind a large, stalled request could inherit upgrade costs triggered by something that never got constructed. That dependency is what made queues fragile.
Most regions have now moved to cluster studies, which group applications received during a defined window and study them as a single group. Shared upgrades are allocated across the cluster rather than assigned to whichever project filed first. FERC Order 2023 pushed the remaining jurisdictional transmission providers toward this first-ready, first-served cluster model, with stricter readiness requirements and penalties for withdrawing late.
How the study phases work
A typical transmission path starts with application validation, where the operator checks that the request is complete, the deposit is posted, and site control meets the tariff standard. Incomplete requests are returned. In a cluster process, validated requests then wait for the window to close before any engineering begins, so the calendar matters as much as the paperwork.
The first engineering phase, often called a feasibility, scoping, or phase one study, runs power flow and short-circuit analysis with the full cluster modeled at its points of interconnection. It identifies which transmission elements overload or fall outside voltage limits under normal and contingency conditions, and produces a first estimate of the network upgrades needed to fix them. This is usually the first cost a developer sees.
The system impact study refines that analysis, and the facilities study prices the specific equipment and construction work. Between phases the operator publishes results, and each project must decide whether to continue, typically by posting additional security that scales with its assigned upgrade costs. The path ends in a signed interconnection agreement that fixes the scope, cost responsibility, and schedule for the upgrades.
How upgrade costs are allocated
Upgrade costs fall into two buckets. Interconnection facilities are the equipment between the project and the point of interconnection, such as the generator tie line and the customer side of the substation, and the developer pays for them outright. Network upgrades are improvements to the shared transmission system, such as reconductoring a line or adding a transformer, that the project triggers or contributes to.
In a cluster, network upgrade costs are typically split among the projects that contribute to an overload, using a method based on each project's share of the flow on the constrained element or its share of cluster capacity. Whether a developer is later reimbursed for network upgrades depends on the region. Some markets credit the cost back through transmission service; others treat it as a participant-funded obligation with no refund.
The practical consequence is that a project's cost is not a property of the project alone. It depends on who else is in the cluster, where they sit electrically, and whether they stay in. A large neighbor that withdraws can shift its share of a common upgrade onto the projects that remain, which is why the restudy after each decision point can move numbers in either direction.
Why withdrawals cascade
Withdrawals are contagious for a mechanical reason. When one project leaves after a study phase, the operator must restudy the remaining projects without it. Upgrades that were shared with the departed project may now be assigned entirely to the survivors, or a different constraint may bind once the flows change. Each restudy produces new cost allocations, which can push additional projects past their economic threshold and trigger another round of exits.
Time compounds the problem. Multi-year study cycles collide with site control terms, offtake windows, equipment reservations, and tax credit qualification schedules. A project that was viable when it filed can lose its land option or its buyer while waiting for a restudy. Withdrawal penalties and higher readiness deposits are designed to keep speculative requests out, which reduces the number of exits that set off the cascade.
What readiness means
Readiness is the set of proofs a transmission provider requires before it will spend engineering effort on a request. Site control is the core requirement: a deed, lease, or option covering the project footprint, with tariffs setting a minimum acreage per MW or a percentage of the required area. Commercial readiness can include an executed offtake agreement, a term sheet, selection in a procurement, or, in place of those, a larger cash deposit.
Readiness escalates through the process. A project that clears the entry bar must demonstrate more at each decision point, usually a higher security posting and firmer site control. Deposits and security are at risk if the project withdraws late, with penalties often scaled to how far the project advanced and how much its exit affects others. Missing a milestone typically forfeits the position, not just the money.
How to read queue data by zone
Public queue data is most useful when filtered to a zone or a set of substations rather than read at the regional level. For each candidate area, sort active requests by point of interconnection and status, then total the MW ahead of or alongside a prospective project. That total, compared against the capacity of the lines and transformers serving the area, is a rough first indicator of whether headroom exists.
Withdrawal history adds the second dimension. A zone where a large share of queued MW eventually exits, especially after the first study phase, is signaling that assigned upgrade costs there tend to be high. Prior study reports for the same cluster area list the constrained elements and the upgrades assigned to fix them, which is a direct preview of what a new request at a nearby node will face.
What to do before you file
Pre-screening has become standard practice because the cost of entering the wrong queue at the wrong node is now much higher than the cost of analysis. Start with published data: utility hosting capacity maps where they exist, the operator's queue with status by point of interconnection, and the most recent cluster study reports for the zone. Benchmark the upgrade costs assigned in those reports against what your project could absorb.
Next, run independent power flow screening. Using a public or licensed base case, a developer or its consultant injects the proposed capacity at the candidate substation and checks thermal and voltage limits under normal and single-contingency conditions. The result is an estimate of headroom, not a substitute for the official study, but it separates points of interconnection with obvious constraints from those worth paying a deposit to test.
Finally, revisit sizing and configuration. Many constraints are sensitive to injection size, so a project scaled to available headroom, or paired with storage that shifts output away from constrained hours, may avoid an upgrade that a larger request triggers. Running this comparison across several candidate nodes before choosing one is cheaper than discovering the answer through a study deposit.
Questions to ask when evaluating a queue position
Whether you are acquiring a project with an existing position or deciding whether to keep one, the same questions apply. What phase has the request reached, and what did the most recent study assign in network upgrades? Which specific elements were constrained, and are those upgrades shared with other projects that might withdraw? How much security has been posted, and how much of it is at risk at the next decision point?
Ask about the neighbors. What share of the cluster in that zone has already withdrawn, and what remains ahead of or alongside the project? Compare the assigned costs against prior study reports for the same zone to spot an outlier. Then check the calendar: when does site control expire relative to the projected interconnection agreement date, and do upgrade in-service dates push commercial operation beyond the offtake window?
None of these questions require proprietary information, but answering them by hand across many zones is slow. Modern screening tools such as Basepoint bring queue status, withdrawal history, and power flow estimates into one view so the comparison can be made with data rather than assumptions before capital is committed.