Grid, interconnection and transformers

Primer

What this stage is

A generator and a data centre are only useful once they are connected. This stage is the wires and the equipment between them: transmission lines, substations, transformers and switchgear, and the process by which a utility or grid operator agrees to connect a large new load.

How it works

A new generator or a new large load applies to the regional grid operator for interconnection and joins a queue. Studies decide what upgrades the connection needs and who pays. In most US regions the queue runs to years, and the study process, not construction, takes most of that time. Large transformers are the physical bottleneck inside the process: few makers, long lead times, and a global order book that data centres now compete for with utilities replacing old equipment.

Utilities plan in multi-year cycles and recover costs from ratepayers, so a sudden gigawatt of demand forces a choice between building ahead of it, charging the data centre for the upgrades, or refusing it. Each region has answered differently.

What to watch

Queue size and typical years to connect, by grid operator.
Large-load interconnection rules: who pays for upgrades, and minimum-take contracts.
Transformer and switchgear lead times.
Utility load forecasts and the data-centre share within them.
Transmission projects approved, and their in-service dates.

How it connects

The grid turns generation into delivered megawatts. A campus that cannot get a connection either waits, builds its own generation, or moves. The queue is the clock the whole build-out runs on.

Figures

Metric	Value	Unit	As of	Scope	Confidence	Source	Note
us_active_interconnection_queue_capacity	2,061	GW	2025-12	US	high	Lawrence Berkeley National Laboratory, Queued Up: 2026 Edition, Characteristics of Power Plants Seeking Transmission Interconnection As of the End of 2025 (June 2026)	1,312 GW of generation plus 749 GW of storage across 8,244 active requests in 7 ISO/RTOs and 47 non-ISO balancing areas, down 10% from 2024 as 750 GW withdrew and 600 GW of new requests arrived; the report's regional table (slide 13) gives West non-ISO 567.4 GW, ERCOT 408.0, MISO 382.2, CAISO 191.3, SPP 171.2, Southeast non-ISO 152.9, PJM 144.3, NYISO 29.2, ISO-NE 14.8.
queue_natural_gas_capacity	253	GW	2025-12	US	high	Lawrence Berkeley National Laboratory, Queued Up: 2026 Edition (June 2026)	Active gas capacity in queues rose 86% in 2025 while solar, storage and wind all fell; gas requests concentrate in MISO and the Southeast, and the report says not all of this capacity will be built.
median_months_interconnection_request_to_operation	61	months	2025	US	high	Lawrence Berkeley National Laboratory, Queued Up: 2026 Edition (June 2026)	Median time from interconnection request to commercial operation for projects that came online in 2025, about 5.1 years, versus 36 months for projects built in 2015 and 22 months in 2008; this is the standard 'years to connect' figure.
queue_completion_rate_2000_2020	13	percent of requested capacity	2025-12	US	high	Lawrence Berkeley National Laboratory, Queued Up: 2026 Edition (June 2026)	Share of capacity that requested interconnection between 2000 and 2020 and had reached commercial operation by end-2025 (19% by project count); most of the rest withdrew, so queue GW overstates likely supply by several times.
queue_annual_throughput_rate_2025	2	percent of active queue capacity reaching operation in the year	2025	US	high	Lawrence Berkeley National Laboratory, Queued Up: 2026 Edition (June 2026)	Of 2,290 GW active at end-2024 only 53 GW reached operation during 2025; EIA separately reports 53 GW of total 2025 capacity additions, so roughly all new capacity passes through these queues.
ercot_active_generation_queue_capacity	408	GW	2025-12	US	high	Lawrence Berkeley National Laboratory, Queued Up: 2026 Edition (June 2026)	Largest ISO queue in the country (the non-ISO West is larger at 567 GW); ERCOT's own count was 453,562 MW of active generation requests as of February 28, 2026, of which storage 177,642 MW, solar 162,927 MW, gas 60,715 MW and wind 47,793 MW (ERCOT House State Affairs deck, April 9, 2026).
ercot_large_load_interconnection_requests	410	GW	2026-03-26	US	high	ERCOT, Update to the Texas House Committee on State Affairs, Pablo Vegas (April 9, 2026)	Large loads (75 MW and above) seeking ERCOT interconnection as of March 26, 2026, about 87% data centres; ERCOT reported 233 GW in December 2025 (almost 300% above end-2024) and told Utility Dive it was tracking more than 438 GW by June 2026, when the PUCT approved a 'Batch Zero' study process (Utility Dive, Jan 6 and Jun 22, 2026).
dominion_data_center_contracted_capacity	53.8	GW	2026-07	Dominion Energy (Virginia)	medium	Virginia Business, Top US data center-serving utility Dominion tops profit estimates (July 31, 2026)	Company-reported data-centre capacity in all contracting stages in Dominion's Virginia territory (the largest data-centre market in the world), up 5.3 GW since December 2025; the figure comes from Dominion's Q2 2026 earnings materials, and its 8-K press release text does not carry the GW number, hence medium confidence.
aep_contracted_load_growth_through_2030	69	GW	2026-06-30	American Electric Power	high	American Electric Power, Form 8-K exhibit 99.1, second-quarter 2026 earnings release (July 30, 2026)	Signed load agreements with hyperscalers, data centres and industrials for load coming online by 2030 across AEP's utilities in PJM, SPP and ERCOT; 6 GW was added in Q2 2026 alone, mostly in Texas, and a year earlier the same figure was 24 GW (Power Engineering, Aug 1, 2025).
pjm_summer_peak_growth_rate_10yr	3.6	percent per year	2026-01-14	US	high	PJM, 2026 PJM Load Forecast Report (posted January 14, 2026)	PJM's own forecast of average summer peak growth over 2026-2036, reaching 222,106 MW in 2036 (a 10-year increase of 65,733 MW) and 253,077 MW in 2046, with data-centre load the stated driver in most zones; this is the grid operator's forecast, not an outturn.
power_transformer_lead_time	128	weeks	2025-06	US	medium	POWER Magazine, Transformers in 2026: Shortage, Scramble, or Self-Inflicted Crisis? (January 2, 2026), citing Wood Mackenzie's Q2 2025 survey	Average delivery lead time for power transformers in Wood Mackenzie's second-quarter 2025 survey, about 2.5 years; the same article reports power transformer prices up 77% since 2019 and a Wood Mackenzie estimate of a 30% supply shortfall for power transformers; the underlying Wood Mackenzie report is paywalled.
generator_step_up_transformer_lead_time	144	weeks	2025-06	US	medium	POWER Magazine, Transformers in 2026: Shortage, Scramble, or Self-Inflicted Crisis? (January 2, 2026), citing Wood Mackenzie's Q2 2025 survey	Average lead time for generator step-up transformers (the unit every new power plant needs), about 2.8 years; the article says demand for GSUs has grown 274% since 2019 and their prices 45%.
queue_active_capacity_pjm	144.3	GW of generation and storage actively seeking interconnection	2025-12	PJM	high	Lawrence Berkeley National Laboratory, Queued Up: 2026 Edition (June 2026), regional table of active queue capacity	A cell of the report's regional table; capacity in the queue, of which about 13% has historically reached operation. ERCOT, the largest ISO queue at 408 GW, has its own row.
queue_active_capacity_miso	382.2	GW of generation and storage actively seeking interconnection	2025-12	MISO	high	Lawrence Berkeley National Laboratory, Queued Up: 2026 Edition (June 2026), regional table of active queue capacity	A cell of the report's regional table; capacity in the queue, of which about 13% has historically reached operation. ERCOT, the largest ISO queue at 408 GW, has its own row.
queue_active_capacity_spp	171.2	GW of generation and storage actively seeking interconnection	2025-12	SPP	high	Lawrence Berkeley National Laboratory, Queued Up: 2026 Edition (June 2026), regional table of active queue capacity	A cell of the report's regional table; capacity in the queue, of which about 13% has historically reached operation. ERCOT, the largest ISO queue at 408 GW, has its own row.
queue_active_capacity_caiso	191.3	GW of generation and storage actively seeking interconnection	2025-12	CAISO	high	Lawrence Berkeley National Laboratory, Queued Up: 2026 Edition (June 2026), regional table of active queue capacity	A cell of the report's regional table; capacity in the queue, of which about 13% has historically reached operation. ERCOT, the largest ISO queue at 408 GW, has its own row.
queue_active_capacity_nyiso	29.2	GW of generation and storage actively seeking interconnection	2025-12	NYISO	high	Lawrence Berkeley National Laboratory, Queued Up: 2026 Edition (June 2026), regional table of active queue capacity	A cell of the report's regional table; capacity in the queue, of which about 13% has historically reached operation. ERCOT, the largest ISO queue at 408 GW, has its own row.
queue_active_capacity_iso_ne	14.8	GW of generation and storage actively seeking interconnection	2025-12	ISO-NE	high	Lawrence Berkeley National Laboratory, Queued Up: 2026 Edition (June 2026), regional table of active queue capacity	A cell of the report's regional table; capacity in the queue, of which about 13% has historically reached operation. ERCOT, the largest ISO queue at 408 GW, has its own row.
queue_active_capacity_southeast_non_iso	152.9	GW of generation and storage actively seeking interconnection	2025-12	Southeast (non-ISO)	high	Lawrence Berkeley National Laboratory, Queued Up: 2026 Edition (June 2026), regional table of active queue capacity	A cell of the report's regional table; capacity in the queue, of which about 13% has historically reached operation. ERCOT, the largest ISO queue at 408 GW, has its own row.
queue_active_capacity_west_non_iso	567.4	GW of generation and storage actively seeking interconnection	2025-12	West (non-ISO)	high	Lawrence Berkeley National Laboratory, Queued Up: 2026 Edition (June 2026), regional table of active queue capacity	A cell of the report's regional table; capacity in the queue, of which about 13% has historically reached operation. ERCOT, the largest ISO queue at 408 GW, has its own row.
ercot_large_load_requests_tracked_gw	474	GW of large loads (75 MW and above) seeking interconnection, about 90% data centres	2026-06-30	ERCOT	high	ERCOT, 'Assessing the Grid', Texas Senate Panel 1 presentation, slide 6 'Large Load Interconnection Requests (as of June 2026)', 2026-07-29	The broadest count, including requests beyond the formal queue; 410 GW at March 26, 2026 and 233 GW in December 2025. Requests, not firm demand: the system peaks near 85 GW.
ercot_large_load_queue_pgrr115_gw	438	GW of large-load interconnection requests in the PGRR115 process, most with no studies submitted	2026-06	ERCOT	high	ERCOT Board of Directors, Item 8 'Interconnection and Grid Analysis Update' (Jeff Billo), June 2026 meeting, slide 2, posted 2026-05-24	The formal queue before ERCOT switched to batch studies on July 10, 2026.
ercot_large_load_approved_to_energize_gw	9.46	GW of large load with ERCOT Approval to Energize	2026-08	ERCOT	high	ERCOT, Monthly Operational Overview, August 2026, slide 9 'Loads Approved to Energize - Observations', posted 2026-09-16	What has cleared every study; against 474 GW requested, about 2%.
ercot_large_load_observed_operating_gw	4.32	GW, non-simultaneous monthly peak consumption of loads approved to energize	2026-08	ERCOT	high	ERCOT, Monthly Operational Overview, August 2026 (April figure 4,006 MW of 9,012 MW approved from the April 2026 overview, https://www.ercot.com/files/docs/2026/05/19/ERCOT-Monthly-Operational-Overview-April-2026.pdf; Ma	ERCOT's own measure of approved load that is actually running; 4.006 GW in April and 4.145 GW in May 2026.

US interconnection queues

LBNL Queued Up · data through 2025 · CC BY 4.0, LBNL and GridTracker · capacity as filed, without the imputed hybrid storage in LBNL's report

Active capacity, GW
Region	Gas	Solar	Wind	Battery	Other	Total
CAISO	3.5	129.0	8.8	47.5	1.9	190.7
ERCOT	44.2	194.8	46.2	120.9	1.8	408.0
ISO-NE	0.1	1.6	6.0	6.8	0.1	14.6
MISO	70.9	165.7	46.7	54.9	11.9	350.1
NYISO	0.0	8.8	7.3	11.1	0.0	27.1
PJM	12.7	67.8	19.3	29.0	1.8	130.6
SPP	35.0	54.9	27.3	30.8	3.1	151.2
Southeast	63.5	52.6	2.6	17.4	7.8	143.8
West	25.2	247.9	57.3	68.0	50.2	448.6
Total	255.1	923.1	221.6	386.6	78.4	1,864.8

Closest to built: interconnection agreement executed, not yet operating, GW
Region	Gas	Solar	Wind	Battery	Other	Total
CAISO	0.6	65.3	8.0	22.4	1.2	97.5
ERCOT	8.3	68.8	15.6	26.6	0.0	119.3
ISO-NE	0.1	1.3	4.7	2.5	0.1	8.6
MISO	1.9	18.8	4.1	1.1	2.3	28.1
PJM	4.0	24.0	3.6	3.2	0.2	35.0
SPP	3.5	16.2	12.2	5.6	0.0	37.6
Southeast	18.3	13.1	1.8	3.9	0.7	37.8
West	3.1	31.3	12.2	9.1	4.8	60.6
Total	39.9	238.8	62.1	74.3	9.3	424.4

Time to connect: median months from request to operation
Year	Overall	CAISO	ERCOT	ISO-NE	MISO	NYISO	PJM	SPP	Southeast	West
2020	45	110	38	–	52	94	40	55	42	37
2021	50	70	44	–	50	82	55	57	45	16
2022	58	105	44	–	58	54	65	81	41	72
2023	56	100	46	–	53	87	67	84	56	50
2024	61	95	44	–	60	–	70	89	63	56
2025	65	110	49	–	–	–	83	66	54	39

Active capacity by proposed online year, GW
Proposed online year	Gas	Solar	Wind	Battery	Other	Total
earlier	17.3	106.6	28.4	18.8	13.3	184.4
2025	12.8	91.1	15.0	21.4	3.4	143.8
2026	17.6	131.9	20.9	46.8	2.6	219.7
2027	28.8	149.4	35.1	80.0	4.6	297.9
2028	56.2	199.2	40.4	112.8	15.0	423.7
2029	28.8	115.6	32.8	42.1	11.0	230.3
2030	54.0	75.1	28.3	28.9	14.9	201.3
later	22.3	48.8	17.6	30.2	10.8	129.7
Not stated	17.1	5.4	3.2	5.4	2.8	34.0
Total	255.1	923.1	221.6	386.6	78.4	1,864.8

Conversions

From → To	Factor	Unit	As of	Confidence	Source	Note
Grid, interconnection and transformers → Data centre shell and cooling	0.65	MW of IT load per MW of facility power drawn (= 1/PUE) at the industry-average PUE	2025-07	high	Uptime Institute, Global Data Center Survey 2025 (keynote report PDF, survey run Apr-May 2025)	1 / 1.54 = 0.649, so a 100 MW grid connection at the industry-average PUE supports about 65 MW of IT load; use this for older or colocation halls, not for new hyperscale AI builds.
Power generation and fuel → Grid, interconnection and transformers	0.74	accredited MW per nameplate MW (PJM ELCC, gas combined cycle, 2027/28)	2027/2028 delivery year	high	PJM, ELCC Class Ratings for the 2027/2028 Base Residual Auction	The quoted row is the table's values in reading order for these classes: Onshore Wind 41%, Offshore Wind 67%, Fixed-Tilt Solar 7%, Tracking Solar 8%, Landfill 48%, Hydro Intermittent 39%, 4-hr Storage 58%, 6-hr 67%, 8-hr 70%, 10-hr 78%, Demand Resource 92%, Nuclear 95%, Coal 83%, Gas Combined Cycle 74%, Gas Combustion Turbine 61%, Gas CT Dual Fuel 77%, Diesel 92%, Steam 72%, Waste to Energy 83%, Oil-Fired CT 80%; a 1,000 MW combined-cycle plant therefore counts 740 MW toward PJM's reliability requirement and a nuclear unit 950 MW.
Grid, interconnection and transformers → Power generation and fuel	1.5	GW of active interconnection-queue capacity per GW of installed US generating capacity (end-2025)	2025-12	high	Lawrence Berkeley National Laboratory, Queued Up: 2026 Edition (June 2026)	2,061 / 1,374 = 1.50 (my arithmetic); LBNL's 1,374 GW installed figure is higher than EIA's 1,280,799 MW of utility-scale capacity at end-2025 (likely a nameplate versus net-summer or coverage difference), so the ratio is 1.5-1.6 depending on the denominator; with 13% historical completion the queue implies perhaps 270 GW of eventual builds (2,061 x 0.13).
Grid, interconnection and transformers → Data centre shell and cooling	0.92	MW of IT load per MW of facility power drawn (= 1/PUE) at Google's fleet PUE	2025-12	high	Google Data Centers, Power usage effectiveness (efficiency page)	1 / 1.09 = 0.917, so a 100 MW connection supports about 92 MW of IT at best-in-class efficiency; new liquid-cooled AI campuses (Microsoft Fairwater, Crusoe Abilene) are designed toward this end of the range.
Grid, interconnection and transformers → Data centre shell and cooling	10.7	USD million of construction cost per MW of capacity (shell, power and cooling; excludes IT)	2025-12	medium	JLL Research, 2026 Global Data Center Outlook (5 Jan 2026)	Global average for 2025; US markets range from $9.5/W (Charlotte) to $13.3/W (Silicon Valley) in Turner & Townsend's index, i.e. $9.5M-$13.3M per MW, with a 7-10% premium for AI-ready liquid-cooled halls; a 1 GW campus is therefore roughly $10-13B before any GPUs.
Power generation and fuel → Grid, interconnection and transformers	0.08	accredited MW per nameplate MW (PJM ELCC, tracking solar, 2027/28)	2027/2028 delivery year	high	PJM, ELCC Class Ratings for the 2027/2028 Base Residual Auction	Tracking solar is accredited at 8% and 4-hour storage at 58% of nameplate, so the 43.4 GW of solar and 24 GW of batteries planned nationally for 2026 would count for only about 3.5 GW and 13.9 GW of firm capacity under PJM's method (43.4 x 0.08; 24 x 0.58, my arithmetic, applied to a national figure for illustration).
Power generation and fuel → Grid, interconnection and transformers	121.7	$ per kW-year of accredited capacity (PJM 2027/28 capacity price converted from $/MW-day)	2025-12-17	high	PJM Inside Lines, PJM Auction Procures 134,479 MW of Generation Resources (December 17, 2025)	$333.44 per MW-day x 365 days / 1,000 kW per MW = $121.71 per kW-year (my arithmetic); this is what a 100 MW data centre's share of PJM capacity costs, about $12.2 million a year before the ELCC and load-forecast adjustments, and it is the price signal that new firm generation earns on top of energy revenue.
Grid, interconnection and transformers → Data centre shell and cooling	0.65	MW of IT load per MW of facility power (1 / PUE, global weighted-average PUE 1.54)	2025	high	Uptime Institute, Global Data Center Survey 2025 (Keynote Report 180, July 2025)	1 / 1.54 = 0.649 (my arithmetic): a data centre drawing 100 MW at the grid connection supports about 65 MW of servers and networking at the industry-average PUE; the figure has barely moved for six years.
Grid, interconnection and transformers → Data centre shell and cooling	0.69	MW of IT load per MW of facility power (1 / PUE, data centres of 20 MW and above, PUE 1.44)	2025	high	Uptime Institute, Global Data Center Survey 2025 (Keynote Report 180, July 2025)	1 / 1.44 = 0.694 (my arithmetic); large, newer facilities of the kind hyperscalers build are more efficient, so a 1 GW grid connection yields roughly 690 MW of IT load rather than 650 MW; facilities commissioned since about 2020 average PUE 1.48.
Grid, interconnection and transformers → Data centre shell and cooling	9	kW per rack (average of modal rack densities, 2025 survey)	2025	high	Uptime Institute, Global Data Center Survey 2025 (Keynote Report 180, July 2025)	Typical rack density across all surveyed data centres, so 1 MW of IT load is about 111 conventional racks (1,000 / 9, my arithmetic); AI racks are far denser (an NVIDIA GB200 NVL72 rack is rated around 120 kW), which is why AI halls need liquid cooling and far more power per square foot.

Players

Company	Ticker	Role	Listed	Note
Hitachi Energy (Hitachi, Ltd.)	TYO:6501	Transformer and grid equipment maker	yes	Announced more than $1 billion of US grid-equipment manufacturing investment in September 2025, including about $457 million for a new large power transformer plant in South Boston, Virginia, citing AI data-centre demand.
GE Vernova (Electrification segment)	NYSE:GEV	Transformers (Prolec GE), switchgear and grid systems	yes	Electrification equipment backlog of $40.6 billion at Q2 2026, up 69% year on year including $5 billion from Prolec GE; data-centre orders topped $5 billion year-to-date, more than double all of 2025.
Siemens Energy (Grid Technologies)	ETR:ENR	Transformers, switchgear and HVDC	yes	Grid Technologies is one of the three main transformer suppliers to the US market; the Q3 FY2026 release (August 5, 2026) reports record order intake and raised revenue guidance for the group.
Eaton	NYSE:ETN	Transformers, switchgear and data-centre electrical equipment	yes	Investing $340 million to raise US three-phase transformer output at a new Jonesville, South Carolina plant with production from 2027, in response to a shortage that has pushed utility transformer lead times to 120 weeks (Utility Dive, Feb 12, 2025).
Dominion Energy	NYSE:D	Utility serving Northern Virginia data centres	yes	Nearly 53.8 GW of data-centre capacity in contracting stages in Virginia as of July 2026, up 5.3 GW since December 2025.
American Electric Power	NASDAQ:AEP	Multi-state utility (PJM, SPP, ERCOT)	yes	69 GW of contracted load growth through 2030 as of Q2 2026 and a $78 billion five-year capital plan weighted to transmission.
PJM Interconnection	private	Regional transmission organisation (13 states plus DC)	no	Largest US grid operator; its board in January 2026 defined large-load additions as 50 MW or more at a single point of interconnection and directed a voluntary Bring Your Own New Generation track plus a reliability backstop procurement.
ERCOT	private	Texas grid operator	no	Tracking about 410 GW of large-load requests (about 87% data centres) as of March 2026 and moving to a batch study process for loads of 75 MW and above with $50,000/MW financial security under the PUCT's proposed rule.

Signals

Date	Kind	Actor	Counterparty	Claim	Value	Confidence	Source
2026-09-16	statement	ERCOT		Of 9,456 MW of large load approved to energize, a non-simultaneous monthly peak of 4,316 MW was observed operating in August 2026	4,316 MW	confirmed	ERCOT Monthly Operational Overview, August 2026 (2026-09-16)
2026-07-30	contract	American Electric Power	hyperscalers and data centres	Signed load agreements of 69 GW for load coming online by 2030 across its PJM, SPP and ERCOT utilities, 6 GW added in the quarter; the same figure was 24 GW a year earlier	69 GW	confirmed	American Electric Power Q2 2026 earnings release (8-K exhibit 99.1, 2026-07-30)
2026-07-29	statement	ERCOT	Texas Senate	Tracking approximately 474 GW of large loads seeking interconnection as of June 2026, about 90% data centres	474 GW	confirmed	ERCOT, Assessing the Grid, Texas Senate Panel 1 (2026-07-29)
2026-04-24	policy	Public Service Commission of Wisconsin	We Energies	Approved We Energies' Very Large Customer and Bespoke Resources tariffs: a 15-year minimum term, a 100 MW threshold and full cost responsibility for dedicated generation	100 MW threshold	reported	BizTimes Milwaukee (2026-04-24)
2026-04-09	statement	ERCOT		Large-load interconnection requests of 75 MW and above reached 410 GW at March 26, 2026, about 87% of them data centres, up from 233 GW in December 2025	410 GW	confirmed	ERCOT update to the Texas House Committee on State Affairs (2026-04-09)
2026-03-31	statement	Georgia Power	large-load customers	12,400 MW of large-load commitments across 31 customers, of which 8,500 MW had broken ground and ten projects were online	12,400 MW	confirmed	Georgia Power, Q1 2026 Large Load Economic Development Report to the Georgia PSC (as of 2026-03-31)
2025-02-19	policy	Indiana Utility Regulatory Commission	Indiana Michigan Power	Approved the large-load tariff settlement in Cause No. 46097; the record names Amazon's New Carlisle campus as a 2,250 MW load, the largest customer in the utility's history	2,250 MW	confirmed	Indiana Utility Regulatory Commission, Order in Cause No. 46097 (2025-02-19)