As electricity demand continues to rise across the United States, policymakers and utilities face mounting pressure to expand generation capacity efficiently and cost-effectively. A new analysis from The Pew Charitable Trusts highlights an underutilized solution—Surplus Interconnection Service (SIS)—that can accelerate new energy deployment by leveraging unused grid capacity at existing power plants.
Unlike traditional interconnection processes that can take an average of five years, SIS enables new generation or storage projects to come online within months by sharing established grid access points.

The Interconnection Challenge
Before delivering electricity to consumers, new power plants must complete a complex interconnection approval process. Projects enter a queue where grid operators conduct detailed studies, determine infrastructure upgrades, and approve maximum generation capacity measured in megawatts (MW). While this safeguards grid reliability, it significantly delays project deployment.
However, many existing power plants do not operate at full capacity year-round. This underutilized grid access presents an opportunity. Surplus Interconnection Service allows new energy resources—often solar arrays or battery storage systems—to colocate at existing facilities and use that unused capacity, effectively bypassing the traditional interconnection queue.
The Federal Energy Regulatory Commission (FERC) authorized broader SIS use in 2018, permitting power plants larger than 20 MW to apply for surplus interconnection additions.
How SIS Expands Energy Generation
SIS offers flexible applications across various energy sources. For example, natural gas “peaker plants,” which operate only during high-demand periods, can integrate solar installations to maximize grid usage throughout the year. Similarly, solar farms that generate electricity only during daylight hours can incorporate battery storage or wind resources to provide power during nighttime or low-sun periods.
This approach enhances overall asset utilization while improving grid efficiency and energy reliability.
Key Benefits for Consumers and Utilities
Surplus Interconnection Service provides several measurable advantages:
- Accelerated energy deployment: SIS supplements traditional interconnection queues, bringing new capacity online more rapidly.
- Reduced land disruption: Projects are colocated with existing plants, minimizing the need for new land development.
- Improved reliability: Combining generation and storage resources increases system flexibility and operational stability.
- Lower congestion and consumer costs: Utilizing unused interconnection rights reduces grid bottlenecks and helps stabilize electricity prices.
- Avoided transmission investments: Additional power can be delivered without constructing costly new transmission lines, which often require years to complete.

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