How much aluminum might U.S. substations need over the next five years? What does a new 345 kV station cost one utility compared with its neighbor? Where are breaker and transformer orders lining up behind the new data center load? These are market-level questions, and the answers to them are scattered across regional plans, rate cases and regulatory dockets, each written in its own format and published on its own schedule.
The New Substation Development Tracker unifies those disparate filings into one dataset. Altogether, it tracks $68 billion of disclosed spend on the substations that tie the U.S. grid together: where lines meet, voltage steps up or down, and new load or generation gets connected. If transmission is the backbone of the grid, substations are its joints.
This week, Halcyon shipped the October update to its New Substation Development Tracker, and with it, achieved coverage of the contiguous United States. Adding ISO New England, South Carolina and Florida brings the tracker to 5,924 planned new and upgraded substations and switching stations across the lower Forty Eight, spanning every U.S. ISO/RTO and transmission planning region.
When we launched in February, we tracked 189.
We started in the West, with CAISO, NorthernGrid and WestConnect, and added ERCOT in March. We moved east in May, adding PJM's expansion plan. MISO, SPP, the Southeast's SERTP and NYISO followed, one a month, taking the count to 5,703 projects across 41 states by September.
Generation queues show what developers hope to build. Substation projects in regional plans and regulatory filings offer a view of where utilities plan to spend. A breaker replacement or a new 345 kV switching station typically appears in a regional plan after a need has been studied, and in many cases approved and budgeted. In our view, that makes substation development a key complement to interconnection queue data as a signal of grid investment.
Of the nearly 6,000 projects in the October release, 4,570 are upgrades to existing stations and 1,336 are new builds. New stations tend to get the ribbon-cuttings, but by project count, upgrades make up most of the data.
Looking at the national picture, there are many different avenues we can explore — for instance, what a new substation costs. Across nearly 1,000 new builds with disclosed capex, the median cost is $11 million, with 14% reported at $50 million or more. Reported costs climb with voltage, from a median of about $5 million below 100 kV to $23 million at 200 to 344 kV, and above $80 million at 500 kV and up. These are nominal figures as reported in filings, and some include associated line work.
Across 1,343 projects that report both a construction-start and an in-service year, the median gap between the two is two years. The spread between regions is wide. In PJM, the median is two years, with 74% reporting two years or less. In SPP, the median is four, and half report five years or more. Voltage explains part of the difference: extra-high-voltage work at 345 kV and above accounts for 45% of SPP's projects in this sample, against 18% of PJM's. Even among EHV projects, the gap remains, with a median of six years in SPP and two in PJM. These figures reflect reported dates, which can shift as projects progress.
For data center developers weighing sites in the Midwest across PJM and SPP, that difference may be worth a closer look. PJM has the larger backlog in the tracker, but its reported timelines from construction to in-service are shorter.
Those are two cuts of the data and plenty more stories to find Watt lies beneath!
Your state, project by project. Use the tracker to pick any state and see every tracked project: new build or upgrade, developer, voltage, in-service year and disclosed cost, linked to the source filing.
What's next? National coverage is a floor, not a finish line. Next, we plan to add county-level location data and link each substation to the data center, battery or gas plant associated with it across Halcyon's other trackers and much more!
Nearly six thousand projects is not a count of substations. It is a count of decisions: a utility deciding a breaker has to go, a planner deciding a new load needs a new 345 kV station, a regulator reviewing the cost. Mapped together, they offer a view of a grid being rebuilt one station at a time, and now, everywhere at once.
See what is being built in your territory. Learn more about the data, or talk to our team for a walkthrough of your state.
Daksh Aggarwal is the data scientist and architect behind Halcyon’s New Substation Development Tracker. Subscribe for more content like this; reach out with questions: sayhi@halcyon.io; follow us on LinkedIn and Twitter