Ask any experienced solar developer what keeps them up at night, and interconnection will be near the top of the list. Connecting a project to the U.S. grid has become the single biggest schedule risk in solar development—often determining whether a late-stage project reaches financial close at all.
Why queues are congested
Interconnection queues swelled as thousands of solar and storage projects sought grid access simultaneously, peaking near 2,600 GW of active capacity at the end of 2023. The backlog eased to roughly 2,060 GW by the end of 2025—driven partly by reform and partly by more than 750 GW of withdrawals in a single year—but solar and storage still dominate the queue, and the fundamental problems remain:
- Multi-year timelines to complete studies and reach agreements
- Uncertain upgrade costs that can render a project uneconomic
- High attrition as speculative projects drop out and reshuffle the queue
What drives interconnection risk
The key variables developers must assess early:
- Queue position and the status of system-impact and facilities studies
- Network upgrade costs and how they are allocated
- Grid capacity in the target substation and region
- Reform timelines as operators implement FERC Order 2023's first-ready, first-served cluster studies—several ISOs paused new requests entirely during the transition, and new cluster windows are only now reopening
Interconnection diligence is a core part of our project underwriting process—we will not commit capital without a clear view of timeline and upgrade exposure.
Managing the bottleneck
Experienced developers de-risk interconnection by:
- Securing strong queue positions early
- Modeling conservative upgrade-cost scenarios
- Maintaining optionality across multiple points of interconnection
- Engaging with grid operators and reform proceedings
For utility-scale solar and solar-plus-storage projects, interconnection outcomes directly shape project economics. The stakes have risen further under the federal tax credit phase-out: a project that misses the beginning-of-construction window must be placed in service by the end of 2027 to remain credit-eligible, making interconnection timing a direct determinant of tax-credit value—not just schedule.
How Sunlight helps
We advance late-stage and shovel-ready projects through permitting, interconnection, and construction with experienced vendors, and we underwrite interconnection risk carefully before committing capital.
Developers navigating the queue can explore our development support or contact our team.