Generation interconnections

The size and location of new or expanded power plants can have significant impacts on the transmission system. These impacts are largely evaluated in MISO Definitive Planning Phase (DPP) process.  Information on the status, as of October 17, 2025, of generation requests in the ATC portion of the MISO generation interconnection queue is provided in this section. There continues to be significant activity in ATC’s footprint, ranging from newly proposed generation projects to cancellation of previously proposed generation projects. 

There are two key aspects in determining the total impacts a proposed new generator may have on the transmission system: 

• impacts of interconnecting the new generator to the transmission system and 
• impacts of using the transmission system to deliver power from the new generator. 

As described in MISO’s Attachment X process, a generator interconnection study is performed in three phases which are all within the Definitive Planning Phase (DPP): System Impact Study (Phase 1, 2 and 3), Interconnection Customer Interconnection Facilities Study (Phase 2 and 3), and Network Upgrade Facilities Study which begins after the System Impact Study is completed in Phase 3.  

The System Impact Study includes a determination of whether the proposed generator and other nearby generators will remain connected to the system under various disturbance situations, such as line trips and equipment failures and includes a fault duty analysis to determine whether existing system equipment can accommodate the increased short circuit fault duty caused by the new generator. Additionally, the System Impact Study will identify solutions for any thermal, stability or fault duty deficiencies. 

Delivery impacts are assessed during the DPP portion of the interconnection study process using the MISO deliverability methodology, which determines whether the output of a new generator is deliverable to the MISO energy market and to what percent if not wholly deliverable. Whatever portion of the new generator that is deliverable may then be used as a Network Resource by Network Customers through MISO’s Module E Resource Adequacy procedures. 

The Interconnection Customer Interconnection Facilities Study is conducted in Phase 2 and 3. It specifies and estimates the time and cost of the equipment, engineering, procurement, and construction of the interconnection facility upgrades identified in the earlier interconnection studies. 

The Network Upgrade Facilities Study is conducted after Phase 3. It specifies and estimates the time and cost of the equipment, engineering, procurement and construction of the network system upgrades identified in the earlier interconnection studies. 

In addition to the DPP process, new resources could also be studied and approved through MISO Replacement process, MISO Surplus process, or the newly established MISO Expedited Resource Addition Study (ERAS) process. These are standalone processes and do not comprise multiple phases. 

• Generator Replacement Study: Generator replacement interconnection is a process that allows new generators to connect to the electric grid at the same point where an existing one is planned to be retired. This is a faster and cost effective alternative to the standard interconnection queue because it leverages the existing infrastructure, leading to a quicker transition to new energy sources with fewer delays and lower costs.  
• Surplus Study: The MISO surplus study process enables a new or hybrid generator to share an existing generator’s interconnection rights at the same point of interconnection (POI), thereby avoiding the need for new network upgrades and securing a faster interconnection. 
• Expedited Resource Addition Study (ERAS): ERAS is a temporary and accelerated process established by MISO in 2025 to speed up the interconnection of new, urgently needed generation projects. This fast-track process is designed to address reliability and resource adequacy concerns by creating an alternative to the standard, often lengthy, interconnection study queues. 

The results of the interconnection studies are needed to develop a comprehensive picture of the transmission facilities that will be required for a proposed generator. Only transmission facilities that result from generators with a signed Interconnection Agreement are included in the 10-Year Assessment models. 

The first portion of the below section provides the status of the generation queue within ATC’s service territory. The second portion of this section describes proposed generation projects for which final interconnection studies have been completed. The third portion of this section describes some of the implications associated with interconnecting generation at various locations within ATC’s service territory. 

ATC Portion of MISO Generation Queue

Over the last ten years (2015 through September 2025), thirty three (33) new generators have gone into service and five uprates or replacements to existing generators have been completed, totaling over 3545 MW. These generators are included in Table PR-26. 

Table PR-26: Generator Requests From Past Ten Years Now In-Service

In-Service Date	Queue Number and Name	Project Capacity (MW)
3/4/2016	J382, RockGen Increase	48.3
4/27/2016	J241, Twin Falls Hydro uprate	3.7
4/29/2017	J557, Garden Corners solar	0.9
5/1/2017	J384, Christiana uprate	21
12/1/2017	J395, Quilt Block Wind Farm	98
3/31/2019	J703, Kuester	131.7
3/31/2019	J704, Mihm	56.5
10/28/2019	J831, Port Washington uprate	40
5/14/2020	J390 & J760, West Riverside	732
11/2/2020	J886, Two Creek Solar	150
9/13/2021	J505, Point Beach Solar Energy Center	100
12/1/2021	J870, Badger Hollow 1	150
1/7/2022	J928, Garden Wind	80
6/2/2022	J1183, Garden Solar	1.35
10/17/2022	J864, Bear Creek Solar	50
1/20/2023	J1188, North Rock Solar	50
1/20/2023	J986, Wood County Solar	150
4/4/2023	J855, Red Barn Wind Farm	100
7/7/2023	R1010, Weston Rice	133
12/23/2023	J871, Badger Hollow II	150
2/9/2024	J1000, Cassville Solar	50
2/9/2024	J1304, Paddock Solar	65
2/9/2024	J1305, Albany Solar	50
2/27/2024	J1002, Wautoma Solar	99
2/27/2024	J1003, Beaver Dam Solar	50
3/1/2024	J1171, Springfield Solar	100
4/12/2024	J1153, Onion River Solar	150
4/16/2024	J1154, Crawfish River Solar	75
5/29/2024	J947, Grant County Solar	200
12/11/2024	J878, Paris Solar	200
3/3/2025	J850, Darien Solar	250
6/1/2025	J1316, Paris Solar	50
Total		3545

Table PR-27 lists the proposed generators in the generation queue for our service territory as of October 17, 2025, who have not yet signed the Generator Interconnection Agreement (GIA). It is important to keep in mind that the status of queued projects changes often as projects enter and withdraw from the queue, sign generator interconnection agreements and start construction. This table lists each proposed generation project and summarizes them by zone and MW amount. These proposed projects also are shown by approximate location in Figure PR-9.

As shown, the total capacity of proposed generators in this portion of the queue is roughly 10.18 GW. Of this proposed capacity, natural gas fired units reflect 37.8 percent, wind 7.4 percent, solar 29.1 percent, storage 24.8 percent, and hybrid 1.0 percent (see Figure PR-10). The hybrid units are combination of storage with wind or solar. Of the proposed capacity, 26.1 percent is in Zone 1, 4.6 percent is in Zone 2, 22.9 percent is in Zone 3, 12.3 percent is in Zone 4, and 34.1 percent is in Zone 5. 

Table PR-27: Proposed Projects Active in the Generation Queue as of October 09, 2023

Zone	Queue #	County	Project capacity (MW)	Interconnection voltage (kV)	Generator technology and fuel
1	J2099	Portage	399.03	345	SOLAR
1	J2107	Portage	399.03	345	SOLAR
1	J2185	Portage	399.03	345	SOLAR
1	J2193	Waushara	100	138	HYBRID
1	J2520	ADAM	200	138	SOLAR
1	J2559	Wood	200	345	SOLAR
1	J2609	Waushara	80	138	SOLAR
1	J2870	Sawyer	243.6	345	SOLAR
1	J2944	Wood	350	345	GAS
1	J3204	Clark	190	345	WIND
1	J3469	Marathon	100	115	WIND
1 Total			2661
2	J2029	Marquette	62.5	138	SOLAR
2	J2316	Dickinson	77.5	138	SOLAR
2	J2678	Delta	150	138	SOLAR
2	J3281	Marquette	170	138	WIND
2	J3800	Baraga	1.8	138	GAS
2	J3756	Marquette	4.2	138	GAS
2 Total			466
3	J1931	Iowa	40	345	WIND
3	J1935	Dane	50	138	SOLAR
3	J1943	Columbia	200	345	SOLAR
3	J1993	Columbia	99	345	SOLAR
3	J2304	Columbia	400	345	STORAGE
3	J2423	Columbia	300	345	STORAGE
3	J2429	Dane	50	69	SOLAR
3	J2666	Walworth	100	138	SOLAR
3	J2947	Rock	205	138	GAS
3	J3152	Green	160	138	GAS
3	J3156	Rock	60	138	GAS
3	J3162	Rock	100	138	STORAGE
3	J3639	Columbia	250	345	WIND
3	J3402	Juneau	200	345	STORAGE
3	R5066	Columbia	20		STORAGE
3	R1060	Green	95		GAS
3 Total			2329
4	J2055	Sheboygan	100	345	SOLAR
4	J2211	Brown	200	138	STORAGE
4	J2326	Outagamie	150	345	STORAGE
4	J3151	Sheboygan	150	345	GAS
4	J3155	Winnebago	150	138	GAS
4	J3160	Fond du Lac	100	345	STORAGE
4	J3466	Winnebago	100	138	SOLAR
4	E0037	Sheboygan	150	345	GAS
4	E0038	Winnebago	150	138	GAS
4	E0016	Calumet	1,203	345	GAS
4 Total			2453
5	J1895	Kenosha	200	138	STORAGE
5	J1934	Kenosha	150	138	STORAGE
5	J2891	Kenosha	50	138	SOLAR
5	J3006	Milwaukee	300	345	STORAGE
5	J3785	Kenosha	200	345	STORAGE
5	J3784	Ozaukee	200	345	STORAGE
5	E0012	Kenosha	1,168	345	GAS
5 Total			2268
Grand Total			10,117

Table PR-28: Requests Previously in the Generation Queue Which Have been Withdrawn/Removed between June 1, 2022 and October 09, 2023

Zone	Queue #	County	Project capacity (MW)	Interconnection voltage (kV)	Generator technology and fuel	Date Withdrawn
1	J2335	Portage	200	115	STORAGE	2025-07-29
1	J2345	Marathon	150	345	WIND	2025-07-29
1	J2365	Portage	160	345	STORAGE	2025-07-29
1	J2366	Portage	160	345	SOLAR	2025-07-29
1	J2557	Wood	100	345	STORAGE	2025-07-29
1	J2833	Wood	40	69	HYBRID	2025-07-29
1	J2439	Marathon	50	345	STORAGE	2025-07-29
1	J1938	Portage	150	345	SOLAR	2024-09-30
1	J1945	Portage	150	345	SOLAR	2024-09-30
1	J2293	Adams	50	69	SOLAR	2024-09-30
1 Total			1210
2	J3638	Dickinson	50	138	STORAGE	2025-09-30
2	J3641	Dickinson	100	138	SOLAR	2025-09-30
2	J3642	Dickinson	60	138	SOLAR	2025-09-30
2	J2354	Marinette	65	69	STORAGE	2025-07-29
2	J3514	Chippewa	100	69	SOLAR	2025-04-17
2	J3648	Baraga	120	120	HYBRID	2025-03-28
2	J3649	Houghton	200	138	HYBRID	2025-03-28
2 Total			695
3	J2324	Winnebago	35	69	HYBRID	2025-07-29
3	J1884	Columbia	200	345	STORAGE	2024-09-30
3	J1964	Columbia	90	345	STORAGE	2024-09-30
3	J1983	Dane	25	138	STORAGE	2024-09-30
3	J2188	Columbia	99	345	SOLAR	2024-09-30
3	J2271	Columbia	200	345	SOLAR	2024-09-30
3 Total			649
4	J2148	Outagamie	150	138	SOLAR	2025-10-14
4	R1014	Sheboygan	100.8	345	STORAGE	2025-07-30
4	R1015	Sheboygan	303.5	345	STORAGE	2025-07-30
4	J2537	Shawano	100	345	STORAGE	2025-07-29
4	J2544	Shawano	95	345	SOLAR	2025-07-29
4	J2834	Fond du Lac	50	69	HYBRID	2025-07-29
4	J3161	Sheboygan	100	138	STORAGE	2025-07-29
4	J1253	Fond du Lac	100	345	SOLAR	2024-10-21
4	J1716	Fond du Lac	100	345	SOLAR	2024-10-21
4	J1994	Fond du Lac	97.088	138	SOLAR	2024-09-30
4	J1996	Shawano	99	138	HYBRID	2024-09-30
4	J2074	Outagamie	75	138	STORAGE	2024-09-30
4	J2218	Manitowoc	150	138	STORAGE	2024-09-30
4	J3332	Calumet	150	345	WIND	2025-09-30
4 Total			1670
5	J3330	Kenosha	705	345	GAS	2025-09-11
5 Total			705
Grand Total			4929

Table PR-29: Active Projects in the Generator Queue in Construction or waiting construction as of October 09, 2023. It includes projects with signed GIA.

Zone	Queue #	County	Project capacity (MW)	Interconnection voltage (kV)	Generator technology and fuel
1	J732	Douglas	562	345	GAS
1	J1502	Juneau	225	345	SOLAR
1	J1508	Marathon	98.9	115	WIND
1	J1573	Portage	250	115	SOLAR
1	J1751	Wood	150.5	138	SOLAR
1	J1752	Portage	148.1	138	SOLAR
1 Total			1435
2	J1251	Marquette	100	138	SOLAR
2	J1750	Marquette	149.7	138	SOLAR
2	J1814	Dickinson	22.5	138	SOLAR
2 Total			272
3	J818	Jefferson	149	138	SOLAR
3	J1214	Dane	300	345	SOLAR
3	J1326	Dane	75	345	STORAGE
3	J1374	Grant	67.2	138	WIND
3	J1377	Rock	98.56	345	SOLAR
3	J1410	Dane	300	345	SOLAR
3	J1411	Dane	75	345	STORAGE
3	J1460	Rock	200	138	SOLAR
3	J1483	Iowa	99	345	WIND
3	J1629	Columbia	200	345	SOLAR
3	J1706	Green	100	138	SOLAR
3	J1732	Columbia	98.4	138	SOLAR
3	J1746	Columbia	150	138	SOLAR
3	J1773	Iowa,Lafayette	300	345	WIND
3	J1779	Dane	200	345	HYBRID
3	J1781	Iowa,Lafayette	300	345	WIND
3	J1824	Columbia	67	138	SOLAR
3 Total			2779
4	J1101	Manitowoc	20	138	STORAGE
4	J1513	Waupaca	300	138	SOLAR
4	J1615	Oconto	150	138	SOLAR
4	J1745	Winnebago	100	138	SOLAR
4	J1793	Sheboygan	75	138	SOLAR
4	R1049	Sheboygan	300	345	Coal
4	R5061	Sheboygan	100	345	Coal
4 Total			1045
5	J1778	Kenosha	100	138	SOLAR
5	R1053	Milwaukee	1138.5	345	GAS
5 Total			1239
Grand Total			6769

Includes projects with signed GIA.

Link to publicly posted MISO generation queue

Implications of generation development

From a transmission perspective, the ability of the transmission system to accommodate new generation is a function of stability, power flow and short circuit analyses. For certain generation technologies, harmonics, fast control interactions and voltage fluctuations may need to be considered as well. In most instances, new generation will require certain transmission system reinforcements to interconnect and deliver the generation output. In a few specific instances, new generation can be beneficial to the transmission system, even deferring or eliminating the need for transmission reinforcements that would be necessary absent the new generation. The ability of generation to defer or eliminate the need for transmission reinforcements also can be a function of the generation location, number of generators, and/or expected generator capacity factor. 

In this section, a general zone-by-zone evaluation of the likelihood of needing or deferring transmission reinforcements for various generator locations is provided. The purpose of these evaluations is to provide a cursory indication to the generation market of the likely magnitude of the impact and the transmission reinforcements that would likely be needed by general location. 

Zone 1

In Zone 1, about 26.1 percent (~2,661 MW, Table PR-27) of the proposed generation is located near the 345-kV infrastructure. Based on studies that ATC has conducted for proposed generation interconnections to date some transmission reinforcements are likely to be required for any significant generation development. The extent and nature of the reinforcements largely would be a function of where the power from the generation is to be delivered.  

The transmission infrastructure in the central portion of Zone 1 includes five 345 kV lines (Gardner Park – Highway 22, Gardner Park – Stone Lake, Gardner Park – Rocky Run, Rocky Run – Arpin, and Rocky Run – Werner West) and two 345 kV tie lines to neighboring entities. These lines significantly strengthen the Weston area, bringing much needed support to the area for both stability and thermal considerations. Furthermore, the new lines included in the MISO Long Range Transmission plan (LRTP) significantly strengthen this area.  

The infrastructure in the southern portion of Zone 1 consists of several 69 kV and 138 kV lines. The existing infrastructure in this portion of Zone 1 is not suitable for significant generation development. 

Three Zone 1 generator projects went in service or are in construction in the last five years. 

Zone 1 Generators In Construction or In Service

Request	Size (MW)	Type	County	State	Status
J1002	99	Solar	Waushara	WI	In Service
J986	150	Solar	Wood	WI	In Service
R1010	133	Natural Gas	Marathon	WI	In Service
J732	527.8	Natural Gas	Douglas	WI	In Construction
J1502	225	Solar	Juneau	WI	In Construction
J1508	98.9	Wind	Marathon	WI	In Construction
J1573	250	Solar	Portage	WI	In Construction
J1751	150.5	Solar	Wood	WI	In Construction
J1752	148.1	Solar	Portage	WI	In Construction

Zone 1 generators in construction or in service in the last 5 years.

Zone 2

ATC has seen substantial interest in siting generators in the Upper Peninsula of Michigan. In Zone 2, about 4.6 percent (~466 MW, Table PR-27) of the active generation in the queue is at various locations throughout the zone. One of the major challenges proposed generation in the Upper Peninsula will face is the limited transmission infrastructure to interconnect and deliver the energy produced by these generators. Since the Upper Peninsula transmission grid was primarily designed to serve local load, transmission upgrades may be required to accommodate these proposed plants. 

There are areas in Zone 2, which currently or will eventually need transmission reinforcements where smaller generation projects could be beneficial in terms of deferring transmission expenditures. The allowable capacity and potential impacts of such generation would depend on location. Impacts like thermal, stability and fault duties would need to be evaluated through the DPP process. 

The following table lists Zone 2 generator projects in service or in construction in the last five years. 

Zone 2 Generators In Construction or In Service

Request	Size (MW)	Type	County	State	Status
J703	131.7	Natural Gas	Marquette County	MI	In Service
J704	56.5	Natural Gas	Baraga County	MI	In Service
J928	80	Wind	Delta County	MI	In Service
J1183	1.4	Solar	Delta County	MI	In Service
J1251	100	Solar	Marquette County	MI	In Construction
J1750	149.7	Solar	Marquette County	MI	In Construction
J1814	22.5	Solar	Dickinson	MI	In Construction

Zone 2 generators in construction or in service in the last five years.

Zone 3

In Zone 3, about 22.9 percent (~2,329 MW, Table PR-27) of the active generation in the queue is at various locations throughout the zone. In recent cycles, there are more proposals in Dane and Columbia Counties and along the Cardinal-Hickory Creek Transmission Line Project corridor (especially in Iowa and Grant Counties). Furthermore, the new line, terminating at Columbia 345-kV Substation, included MISO Long Range Transmission plan (LRTP) will significantly strengthen the area. Furthermore, the new line, terminating at Columbia 345-kV Substation, included MISO Long Range Transmission plan (LRTP) will significantly strengthen the area. 

Similarly, the southeast portion of Zone 3 continues to be an attractive location for siting generation. However, generation studies completed in the southwest corner of the state have demonstrated that siting large amounts of generation in rural areas may require substantial upgrades to the transmission system to ensure reliable operation. 

The following table lists Zone 3 generator projects in service or in construction in the last five years. 

Zone 3 Generators In Construction or In Service

Request	Size (MW)	Type	County,	State	Status
J850	100	Wind	Rock	WI	In Service
J855	100	Wind	Iowa	WI	In Service
J864	50	Solar	Richland	WI	In Service
J870	200	Solar	Iowa	WI	In Service
J871	100	Solar	Iowa	WI	In Service
J947	200	Solar	Grant	WI	In Service
J1000	50	Solar	Grant	WI	In Service
J1003	50	Solar	Dodge	WI	In Service
J1154	75	Solar	Jefferson	WI	In Service
J1188	50	Solar	Rock	WI	In Service
J1304	65	Solar	Rock	WI	In Service
J1305	49.9	Solar	Green	WI	In Service
J818	149	Solar	Jefferson	WI	In Construction
J1214	300	Solar	Dane	WI	In Construction
J1326	75	Storage	Dane	WI	In Construction
J1374	67.2	Wind	Grant	WI	In Construction
J1377	98.56	Solar	Rock	WI	In Construction
J1410	300	Solar	Dane	WI	In Construction
J1411	75	Storage	Dane	WI	In Construction
J1460	200	Hybrid	Rock	WI	In Construction
J1483	99	Wind	Iowa	WI	In Construction
J1629	200	Solar	Columbia	WI	In Construction
J1706	100	Solar	Green	WI	In Construction
J1732	98.4	Solar	Columbia	WI	In Construction
J1746	150	Solar	Columbia	WI	In Construction
J1773	300	Wind	Iowa, Lafayette	WI	In Construction
J1779	200	Hybrid	Dane	WI	In Construction
J1781	300	Wind	Iowa, Lafayette	WI	In Construction
J1824	67	Solar	Columbia	WI	In Construction

Zone 3 generators in construction or in service in the last five years

Zone 4

In Zone 4, about 24.1 percent (~2,453 MW, Table PR-27) of the active generation in the queue is at various locations throughout the zone. . Given the nature of the issues in Zone 4, it is unlikely that new generation will significantly alter the need for the major transmission reinforcements contemplated in that zone.  In recent generation studies, more stress on the 138-kV paths from Pulliam to Highway V and North Appleton – Lost Dauphin is observed and may need substantial reinforcements if the new generation projects move forward. 

One area where generation could defer the need for transmission reinforcements is in Door County, provided such generation is small-scale and appropriately located. Currently, the northern portion of the county is served radially and electric service is subject to interruption for the loss of the single 69 kV line serving the area. The voltage profile in Door County is projected to precipitate the need for reinforcements in the future. Small-scale generation potentially could defer some of these reinforcements. 

The following table lists Zone 4 generator projects in service or in construction in the last five years. 

Zone 4 Generators In Construction or In Service

Request	Size (MW)	Type	County, State	State	Status
J505	99	Solar	Manitowoc Wis.	WI	In Service
J886	150	Solar	Manitowoc Wis.	WI	In Service
J1153	150	Solar	Sheboygan Wis.	WI	In Service
J1171	100	Solar	Dodge	WI	In Service
J1101	20	Storage	Manitowoc	WI	In Construction
J1513	300	Solar	Waupaca	WI	In Construction
J1615	150	Solar	Oconto	WI	In Construction
J1745	100	Solar	Winnebago	WI	In Construction
J1793	75	Solar	Sheboygan	WI	In Construction
R1049	300	Coal	Sheboygan	WI	In Construction
R5061	100	Coal	Sheboygan	WI	In Construction

Zone 4 generators in construction or in service in the last five years.

Zone 5

In Zone 5, about 22.3 percent (~2,268 MW, Table PR-27) of the active generation in the queue is at various locations throughout the zone.  The developments related to Microsoft’s large data center load in Southeast Wisconsin are expected to get some reinforcement to the local transmission capacity and that may make it attractive for new generators to locate there.  

The following table lists Zone 5 generator projects in service or in construction in the last five years. 

Request	Size (MW)	Type	County, State	State	Status
J831	40	Gas	Ozaukee	WI	In Service
J878	200	Solar	Kenosha	WI	In Service
J1316	50	Storage	Kenosha	WI	In Service
J1778	100	Solar	Kenosha	WI	In Construction
R1053	1138.5	Gas	Milwaukee	WI	In Construction