The Interconnection Queue is the formal waiting list managed by utilities, ISOs, or RTOs that tracks all solar, storage, and renewable energy projects requesting permission to connect to the electrical grid. When a developer submits an interconnection request, the project enters this queue and moves through a structured evaluation process that includes feasibility studies, system impact assessments, upgrade cost estimates, and final interconnection approval.

For solar developers, EPCs, and large C&I or utility-scale project owners, the interconnection queue is one of the most important—but often the most time-consuming—stages of project development. Queue delays can significantly impact project timelines, financing, construction start dates, and customer onboarding workflows. Understanding the interconnection queue and its implications is essential for solar businesses, especially those managing multi-megawatt pipelines.

The interconnection workflow often aligns with tools inside platforms like Solar Designing and planning tools available in the Solar Project Planning Hub.

• The Interconnection Queue is the official waiting list for connecting solar projects to the electrical grid.
• Queue position determines how fast a project completes technical studies and receives approval.
• Delays are common, especially at transmission level, due to grid capacity constraints and study backlogs.
• Developers should submit complete applications, anticipate upgrade costs, and track queue progress closely.
• Interconnection timelines significantly impact financing, construction schedules, and overall project viability.

What Is an Interconnection Queue?

An Interconnection Queue is the official list of all energy projects waiting for grid interconnection approval. Every grid authority—such as CAISO, PJM, MISO, ISO-NE, ERCOT, and regulated utilities—maintains its own queue.

When a solar project is submitted for interconnection, it is added to the queue in the order received. Its position determines:

• When studies will occur
• When upgrades are assessed
• Estimated timelines for approval
• Potential costs for system modifications
• Priority relative to other projects

This queue process exists to ensure grid reliability, proper system planning, and safe integration of new distributed or utility-scale generation.

Related terms include Interconnection Agreement, Grid Code, and Grid-Tied System.

How the Interconnection Queue Works

Although each utility or ISO may differ in process, most follow a similar multi-stage structure:

1. Application Submission

The developer submits technical details including:

• System size (kW/MW)
• Location and point of interconnection
• Inverter data
• Single-line diagrams
• Load flow assumptions

See Electrical Single-Line Diagram.

2. Feasibility Study

Initial analysis to identify whether grid upgrades might be necessary.

3. System Impact Study

A deeper engineering review that examines:

• Load flow
• Short-circuit impact
• Voltage regulation
• Protection coordination
• Transmission or distribution constraints

This is often the most time-consuming part.

4. Facilities / Upgrade Study

If grid upgrades are required, the utility estimates:

• Cost of system upgrades
• Timelines
• Construction requirements

5. Draft Interconnection Agreement Issued

The agreement outlines:

• Upgrade costs
• Project responsibilities
• Study results
• Timelines for energization

See Interconnection Agreement.

6. Final Approval & Construction

Once the agreement is executed, the project moves toward construction and commissioning.

Types / Variants of Interconnection Queues

1. Distribution-Level Queue

Used for residential, commercial, and small C&I projects connecting to distribution grids (typically ≤10 MW).

2. Transmission-Level Queue

Used for utility-scale projects connecting to high-voltage transmission lines.

3. Cluster-Study Queue

Many ISOs now analyze groups of projects together to reduce study bottlenecks.

4. Fast-Track / Simplified Review Queues

Available for small rooftop or behind-the-meter systems in compliant circuits.

How It’s Measured

Interconnection queues are tracked using:

Queue Position

The order of project submission and evaluation.

Study Timelines

Typical ranges vary from weeks to years depending on ISO.

Upgrade Cost Estimates

Transmission or distribution upgrades can range from thousands to millions.

MW Capacity

Used to determine grid impact.

Project Status Labels

Examples include:

Pending → Under Study → Assigned Upgrades → Awaiting Agreement → Approved

Typical Values / Ranges

Queue delays have become a major national bottleneck due to surging renewable applications.

Practical Guidance for Solar Developers & EPCs

1. Submit complete, error-free applications

Missing documentation can push a project to the back of the queue.

Use electrical diagrams, load data, and layout designs from Solar Designing.

2. Understand grid constraints early

Use site evaluation tools and engineering assessments before submission.

3. Anticipate upgrade costs

Large projects often require:

• Transformer replacements
• Substation expansions
• Feeder upgrades

4. Use project management tools

Track queue status, timelines, and study milestones in your development pipeline.

See Solar Project Planning Hub.

5. Communicate delays to customers early

Interconnection timelines often influence:

• Financing
• Permitting
• Construction schedules
• PTO (Permission to Operate)

6. Consider alternative POI (Point of Interconnection)

A nearby circuit or substation may offer faster approval.

7. Monitor policy changes

Many ISOs now introduce reforms to shorten queue times.

Real-World Examples

1. Residential Rooftop Solar

A 9 kW system enters a fast-track queue and receives approval within 10 days, allowing installation to begin immediately.

2. Commercial Warehouse Project

A 650 kW rooftop system enters the distribution queue and requires a minor transformer upgrade. Interconnection approval takes 4 months.

3. Utility-Scale Solar Farm

A 120 MW solar project enters a transmission-level queue. Impact studies show the need for significant upgrades, resulting in a 2-year approval timeline before construction can begin.

• Interconnection Agreement
• Grid-Tied System
• Grid Code
• Electrical Single-Line Diagram
• Utility-Scale Solar