The largest renewable energy infrastructure project in the United States has begun generating electricity, placing transmission operators, interconnection regulators, and storage planners under real-world stress for the first time at gigawatt scale. The SunZia Wind and Transmission project, developed by Pattern Energy in New Mexico and Arizona, broke California's wind generation record on March 25 when the state reached 6,654 MW of wind output, surpassing the prior record of 6,429 MW that had stood for nearly four years, according to grid observers. CAISO notified FERC that it had recently taken operational control of the SunZia project, marking the moment the grid operator assumed formal responsibility for the infrastructure.
Background
SunZia Wind and Transmission is the largest clean energy infrastructure project in US history, according to developer Pattern Energy. The project comprises a 3,650 MW wind farm across central New Mexico, paired with a 553-mile, ±525 kV high-voltage direct-current (HVDC) transmission line running from New Mexico to the Pinal Central 500 kV substation near Casa Grande, Arizona, where it connects to the broader Western grid via the Palo Verde hub. Of that wind capacity, 2,131 MW is designated for delivery to California via CAISO's system. The project secured $11 billion in financing in late 2023, including $8.8 billion in construction and term facilities and a $2.25 billion tax equity term loan facility.
The HVDC transmission route illustrates the systemic bottleneck facing future deployments. According to engineering documentation from the American Society of Civil Engineers, the SunZia transmission line route took 17 years to receive regulatory approval-a timeline engineers and planners now cite as a cautionary benchmark as the industry prepares for hundreds of comparable projects. GE Vernova delivered all 674 turbines it built for the project by February 2025, and Vestas Wind Systems confirmed all 242 of its turbines had been installed before grid commissioning began.
Interconnection Queue Pressure and Policy Response
SunZia's first megawatts land on a grid that remains structurally overstretched. According to Lawrence Berkeley National Laboratory's Queued Up: 2025 Edition, as of the end of 2024, approximately 10,300 projects were actively seeking grid interconnection in the US, representing 1,400 GW of generation capacity and approximately 890 GW of storage. Most projects that apply for interconnection are ultimately withdrawn, and those that are built are taking longer on average to complete the required studies and become operational, the report noted.
The Federal Energy Regulatory Commission's landmark Order 2023, issued in July 2023, replaced the longstanding first-come, first-served approach with a "first-ready, first-served" cluster study model. FERC adopted the reforms to reduce backlogs, improve certainty in interconnection processes managed by dozens of transmission providers, and ensure access to the grid for new technologies. Implementation, however, remains uneven. According to the Solar and Storage Industries Institute, total interconnection queue capacity dropped from 2,600 GW in 2023 to 2,300 GW in 2024, the first decline in at least a decade, though the institute cautioned that the decrease largely reflected existing projects reaching commercial operation and paused application windows at CAISO and PJM-rather than confirmed reform-driven progress. Both CAISO and PJM were not accepting new interconnection applications in 2024 as they worked through backlogs and implemented process reforms.
Berkeley Lab research published in Joule found that renewable energy projects face significantly higher interconnection costs than fossil fuel projects, with a quarter of withdrawn projects incurring average costs of $373 per kW versus $73 per kW for those completing the study process. A key driver of higher interconnection costs is network upgrade expenses, which are often fully or partially billed to project developers to overcome transmission constraints.
Storage Integration and the Reliability Equation
Battery storage is emerging as a parallel track to transmission reinforcement. According to the US Energy Information Administration, US utility-scale battery storage capacity grew 58.4% in 2025, adding 15.77 GW of new capacity, with developers planning to add a further 24 GW in 2026. The World Resources Institute noted that two of the largest battery and solar co-located facilities came online in 2025 in Kern County, California and Wharton County, Texas, providing operational data on how co-location affects interconnection dynamics and grid dispatch.
The DOE's recently launched SPARK program-a $1.9 billion notice of funding opportunity targeting transmission upgrades via reconductoring and advanced transmission technologies-has concept papers due April 2, 2026, with project selections expected in August 2026. The program prioritizes projects that increase transfer capability, enhance reliability and resource adequacy, and support growing electricity demand from large new loads such as data centers and industrial clusters, according to Perkins Coie's analysis of the program terms.
Outlook
SunZia sets a benchmark that will be difficult to replicate quickly under current conditions. The only US renewable project of comparable scale, the Chokecherry and Sierra Madre 3.5 GW Wyoming wind project, is projected to start delivering power in 2029, according to EIA data. Meanwhile, federal tax credit deadlines-requiring wind and solar projects to begin construction by July 2026 or be placed in service by end of 2027 to qualify for investment and production tax credits under H.R. 1-are compressing developer timelines further. Grid operators, regulators, and developers now face the task of extracting scalable lessons from SunZia's commissioning before that window closes.
