The Utility Publishes the Process. Not the Price of Finding Out.

Ask how long it takes to connect a 100 MW load and you will not get one number. SPP says its new large load process can deliver a clear path to interconnection agreements within 90 days. MISO says a large load can get MISO approval within 120 days, once studies are complete and agreements are signed. ERCOT closed submissions for its first batch study on 10 July 2026 and expects the resulting transmission plan in autumn 2027.

Those are not comparable numbers. One counts a study cycle, one counts an approval after the hard work is done, and one counts a plan that covers many projects at once.

The regulator agrees the picture is unsettled. On 18 June 2026 the Federal Energy Regulatory Commission opened proceedings against all six organized markets. In one of about twenty preliminary findings, its order to ISO New England says the Commission "preliminarily find[s] that ISO-NE's Tariff appears to be unjust and unreasonable because it lacks a definition of large load, as a new category of load." Others concern the risk of cost shifting between customers. These are preliminary findings in a show cause proceeding, not settled law.

So rather than compare markets, follow one path all the way down.

One service path, in public documents

Take a new 100 MW load in south east Wisconsin. Here is what a developer can establish before speaking to anyone.

The tariff is not a choice. Rate Schedule VLC, sheet 238 of We Energies' filed rates, says it "shall be mandatory for any eligible customer whose aggregated load forecast equals or exceeds 100 MW of new electric load that does not currently exist in any Wisconsin utility's service territory." The same sheet closes the alternatives. A load served under it "will not be eligible for service under any other tariff," apart from the companion Bespoke Resource tariff.

The terms are set, and they moved recently. Deciding docket 6630-TE-113 on 24 April 2026, the Public Service Commission of Wisconsin made four changes. It extended the minimum initial term to 15 years. It lowered the eligibility threshold from 500 MW to 100 MW. It removed a capacity only option that would have let these customers pay for 75 percent of the costs of generating facilities. And it approved a full benefits model requiring them to carry 100 percent, which the Commission said protects existing customers from absorbing the difference.

The security is a formula. The tariff sets an annual VLC Security amount based on the monthly charges billed in June, July and August of the prior year, replenished each 1 January. A customer who can evidence financial strength greater than ten times that amount can satisfy the requirement differently.

The gates are published. American Transmission Company's load interconnection guide sets out the sequence: a Load Interconnection Request Form, a receipt notice, an initial review, then project development, Best Value Planning scoping, an interconnection agreement and regulatory approvals.

One deadline is committed. Within 20 business days of the request being deemed complete, ATC will respond.

That is a lot of certainty for a developer who has not spent anything yet.

Where the record stops

Read what that 20 day response actually contains. ATC will tell the customer one of two things: that its initial assessment indicates "minimal or no anticipated upgrades," or that "significant upgrades" are likely, in which case it will seek a scoping conversation to schedule Best Value Planning.

That is a directional screen. It is not a megawatt figure, not a delivery date, and not a project commitment. The guide is equally plain about what follows. Indicative studies "are intended solely to offer preliminary insights into the potential transmission system impacts and required upgrades." They "do not serve as substitutes for System Impact Studies, and do not constitute project commitments." The answer a developer actually needs sits further down.

Those studies run under a study agreement. The interconnection guide says one is entered into for capacity studies, including a high level capacity study covering several locations at once. Its own revision history refers to guidance on "when ATC charges the customer for a study." So the charging exists.

The amount does not appear in the tariff or in the interconnection guide. Not in the materials we reviewed. It is settled between the parties in the study agreement.

You can see the generators. You cannot see the loads

There is a second thing the record does not show, and it may matter more than the first.

ATC maintains a Distribution to Transmission interconnection queue, under the MISO tariff, tracking every active load interconnection project. Position in it follows from the formal receipt of a completed request form, and ATC "retains the discretion to adjust prioritization" for factors including the requested in service date.

So the queue exists. It is simply not published.

Compare that with generation. Every generator seeking to connect in Wisconsin sits on a public list that anyone can download, with its capacity, its connection point and its status. We ingest 262 Wisconsin generator queue entries from it.

A developer can therefore inspect the public generation queue in detail, while having no comparable view of the large loads seeking service from the same transmission system. The information exists, at the transmission owner, in a queue built under a federal tariff. It is not disclosed, and position in it is partly discretionary.

That is a structural blind spot in every public siting analysis, including ours.

What that means commercially

Two sites can look equally viable on everything the filings settle. Same tariff, same term, same security formula, same published gates.

They can still differ enormously in what has to be spent and committed before either one returns a usable answer. Study costs, deposits, project development spend and elapsed time can accumulate before the first credible megawatt and date answer arrives. None of that difference is visible in a tariff.

We do not have enough observations yet to put numbers against that, and inventing them would be worse than leaving the gap open. But the gap is now specific. It is the price of the next gate, what the payment buys, whether it is refundable, and how long the answer takes to arrive.

That is a question to ask a utility in the first conversation rather than discover in the fourth.

Even the public layer needs reading

The parts of the record that are public still do not mean what they appear to mean.

Committed transmission investment is the clearest example. Approved projects are public, located, dated and costed. A site with a billion dollars of nearby work looks like a site the grid is preparing to serve.

We screened Wisconsin's MISO footprint from primary filings. Of the committed transmission behind the twenty best screened locations, 1.81 billion dollars is directly attributable to identified large loads, with a further 548 million where a named load is one of several stated reasons for a project. One project's purpose, in the transmission owner's words, is "to reliably serve a load interconnection request by We Energies to serve a new large load addition in the Port Washington area."

That investment is real. It is just not evidence of room for the next customer.

What to do with this

Establish everything the filings settle before spending anything. Which tariff applies and whether it is mandatory. The term. The security formula. The gate sequence and the one or two deadlines that are committed. Whether nearby transmission was built for somebody else.

Then treat the missing number as the opening question. What does the next gate cost, what does that payment buy, is it refundable, and when does the answer arrive.

The tariff tells you the commercial obligations if the project proceeds. The interconnection guide tells you the gates you must pass. Neither tells you the price of finding out whether the site works.

That is the number to ask for first.

Tafel Power is building Power Diligence Intelligence to structure this analysis across utility territories and power markets.

Sources

• Wisconsin Electric Power Company, Volume 19 electric rates, Very Large Customer and Bespoke Resources tariff sheets.
• Public Service Commission of Wisconsin, decision on the Very Large Customer and Bespoke Resources tariff, docket 6630-TE-113, announced 24 April 2026.
• American Transmission Company, Load Interconnection Guide, revision 15, August 2025. Sections 2.1 process initiation, 2.1.1.5 notification of initial review, 2.1.3 economic development prioritization.
• Federal Energy Regulatory Commission, order instituting proceeding under section 206 of the Federal Power Act, ISO New England Inc., Docket No. EL26-72-000, 195 FERC ¶ 61,215, 18 June 2026. Parallel proceedings opened for the other organized markets the same day.
• Southwest Power Pool, High Impact Large Load integration page. MISO, Large Load Interconnection page. ERCOT Batch Zero, approved by the Public Utility Commission of Texas 18 June 2026.
• MISO MTEP Appendix A Status Report, read at facility grain, with American Transmission Company and Commission project records for the Ozaukee County and Racine County projects.

Method and limits

The Wisconsin tariff changes are as announced by the Commission on 24 April 2026 in docket 6630-TE-113. The written order governs, and anyone relying on these terms should read it rather than this summary.

The statement that study fees are absent refers to the utility and transmission owner materials listed above. Fees may be stated in documents we have not reviewed, or in the study agreement itself, which is not public.

The Wisconsin transmission figures come from a desktop screen of public filings, counted at project level, including where one facility spans two substations. Counting at substation level would double count a shared facility.

A project is attributed to a named load only where the filing says the project exists to serve it. The two loads behind that figure sit at different stages of commitment, one operating and one announced, so the attribution describes the stated purpose of the transmission rather than the contractual status of the customer.

The screen ranks locations. It does not size them, and it states no available megawatt figure for any location, because no public document supports one.