State of the Interconnection 2026
Planned-to-Actual Resource Additions
Entities forecast a 33% increase in annual demand over the next decade. They plan to add new resources at an unprecedented rate to meet this demand, but can they keep pace? In 2025, 67% of the planned resource capacity additions came online, matching the three-year average.
Resource Portfolio
The Western Interconnection's resource portfolio continues to evolve.
- Nearly 85% of the capacity added in 2025 was inverter-based resources (IBR).
- 1.7 GW of natural gas-fired generation were added in 2025, down from 5.5 GW added a year ago.
- 2.2 GW of coal-fired generation were retired, an increase from 0.9 GW retired in 2024.
- 1.2 GW in coal retirements were delayed after the Department of Energy issued emergency orders.
The new resources, combined with the retirements, continue the rapid transformation of the resource mix away from baseload generation to variable resources that do not generate electricity at nameplate capacity at all times.
Capacity
Approximately 18 GW of capacity were added in 2025, mostly solar andbattery storage. That is down from 24 GW added in 2024.
Interconnection-wide, the nameplate capacity of installed resources is approximately 337 GW.
|
Resource |
Installed Capacity |
Percentage of Resource Mix |
Change from Previous Year |
|---|---|---|---|
|
Natural Gas |
111 GW |
33% |
-1.2% |
|
Hydro |
76 GW |
23% |
-0.8% |
|
Solar |
49 GW |
15% |
+1.1% |
|
Wind |
41 GW |
12% |
-0.1% |
|
Battery Storage |
25 GW |
7% |
+1.9% |
|
Coal |
19 GW |
6% |
-0.9% |
Generation
Capacity factor is the ratio of energy produced by a generating unit over a period of time to the amount of energy it would have generated at nameplate capacity. The capacity factor of variable resources like IBRs is lower than baseload resources like coal, natural gas, and nuclear. The capacity factor for natural gas units can be misleading since they are often used for load balancing or as peaking plants and do not generate constantly.
Inverter-based Resources
In 2025, approximately 15 GW of IBR capacity were added in the Western Interconnection, including:
- 7.6 GW battery storage, bringing the 2025 interconnection-wide nameplate capacity of battery storage to approximately 25 GW
- 6 GW solar (49 GW capacity)
- 1.4 GW wind (41 GW capacity)
IBRs and Demand
In the Western Interconnection in 2025, the percentage of demand met by IBRs (IBR/demand ratio) ranged from around 10% in the early morning hours year-round, to almost 40% in the afternoon in the spring. The IBR/demand ratio varies by subregion, however.
- In the SW subregion, where solar generation is the main IBR resource, the percentage of demand met by IBRs exceeded 50% between 11 a.m. and 2 p.m. daily in March and April.
- In the Rocky Mountain subregion, the percentage of demand met by IBRs exceeded 40% between 9 a.m. and 4 p.m. daily between March and May and rarely dropped below 30% throughout the year, due primarily to an abundance of wind generation.
- In the California subregion, where solar is also the predominant IBR resource, the IBR/demand ratio exceeded 50% between 3 p.m. and 5 p.m. daily from April through July. The ratio exceeded 40% between 11 a.m. and 6 p.m. daily from the beginning of April through the end of July.
Natural Gas
In 2025, entities added 1.7 GW of natural gas-fired capacity, down from 5.5 GW added in 2024.
Natural gas-fired generation makes up one-third of the resource mix in the Western Interconnection, with 111 GW of nameplate capacity, more than any other generation resource.
Retirements
In 2025, entities retired 2.6 GW of generation capacity. Nearly all of the retired capacity was coal-fired (2.2 GW).
Nameplate capacity of coal-fired generation in the Western Interconnection fell to roughly 19 GW, less than battery storage capacity for the first time.
New Resources
The nameplate capacity of new resources added in 2025 (18 GW) is approximately 67% of what was planned (27 GW).
Of the additions, 0.8 GW of hydro came online (at the Site C facility in British Columbia). Hydro has the second-most capacity of any resource in the Western Interconnection at 76 GW.
IBR Registration Initiative
The IBR Registration Initiative was launched in 2023 to address the reliability challenges created by the integration of inverter-based resources (IBR). The initiative is the result of a FERC directive in 2022, after several system disturbances tied to IBRs. FERC’s directive called on NERC and the ERO Enterprise to identify and register the owners and operators of IBRs that have an “aggregate, material impact on the reliable operation” of the bulk power system. Over the next two years, NERC, along with WECC and the ERO Enterprise members, worked to identify applicable facilities in advance of a May 2026 deadline.
Identifying and registering these entities allows WECC to ensure all NERC Reliability Standards are met at the generating facilities and to conduct outreach with the facility owners and operators, to ensure they are aware of the reliability risks posed by IBRs and are working to mitigate them.
WECC expects the effort to result in the registration of almost 180 new generator owners and operators, in addition to increased awareness and improved reliability and security among existing entities.
Electric-Natural Gas Coordination
The importance of coordination among the electric and natural gas industries drew attention in 2025:
- Representatives from both industries held the Regional Energy Symposium in the Pacific Northwest
- NERC published its Electricity-Natural Gas Strategy, which calls for increased coordination of the natural gas and electric infrastructure to ensure reliability, resilience, and security.
- The National Petroleum Council issued a report in late 2025, at the request of Energy Secretary Chris Wright, with recommendations for addressing “misalignment” between the two industries.
NERC has called for formalized coordination between the two industries, while working with WECC and the other members of the ERO Enterprise to raise awareness of the issue, enhance Reliability Standards that mitigate the reliability risks associated with extreme weather, and establish communication protocols between grid and generator operators.
Department of Energy issues emergency orders
DOE issued more than a dozen emergency orders pursuant to 202(c) of the Federal Power Act in 2025. Two affected resources in the Western Interconnection:
- On December 16, 2025, DOE directed plant owner TransAlta to ensure Unit 2 of the Centralia Generating Station in Washington remained available for operation through mid-March 2026. Unit 2 has a 730-MW nameplate capacity. The plant is scheduled for conversion from coal to natural gas. The order was renewed for 90 days in March 2026.
- On December 30, 2025, DOE ordered the co-owners of Unit 1 at the Craig Station in Colorado to continue to operate past its planned retirement date of December 31, 2025. The unit has a nameplate capacity of 450 MW. The order was renewed for 90 days in March 2026, and the plant was restarted in April 2026.
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