Interconnection Documents are the official set of technical, electrical, and administrative paperwork required by a utility company to approve and connect a solar PV system to the grid. These documents provide detailed information about the system’s design, safety mechanisms, equipment specifications, and grid impact, allowing the utility to evaluate whether the installation complies with electrical codes, utility interconnection rules, and local grid capacity constraints.

Every grid-tied solar project—residential, commercial, or utility-scale—must submit accurate and complete interconnection documents before receiving permission to operate (PTO). These documents are central to project planning workflows and are prepared using tools such as Solar Designing and proposal-to-permit pipelines like the Solar Project Planning Hub.

• Interconnection Documents are required by utilities to evaluate and approve grid-tied solar projects.
• They include SLDs, site plans, spec sheets, load studies, and compliance statements.
• Accuracy and completeness significantly impact approval timelines.
• Requirements vary by project size—residential is simple, utility-scale is complex.
• SurgePV tools streamline preparation by generating precise layouts and diagrams.

What Are Interconnection Documents?

Interconnection documents are the formal application package developers submit to the utility. They communicate what the system is, how it is wired, what equipment is used, how it impacts the grid, and how safety requirements are met.

They typically include:

• System layout and single-line diagrams
• Site maps and equipment locations
• Inverter specifications
• Stringing and electrical design details
• Load calculations and service rating
• Utility metering and disconnect information
• Compliance statements with NEC, IEEE, and utility rules

These documents validate that the system will safely and reliably connect to the grid.

Related foundational terms include Interconnection Agreement, Inverters, and Stringing & Electrical Design.

How Interconnection Documents Work

1. System Design Is Finalized

The solar designer creates a complete layout using tools like Solar Designing and shading engines such as Shadow Analysis.

2. Electrical Details Are Compiled

Including module strings, inverter configurations, AC/DC wiring, system voltage, and breaker ratings.

3. Single-Line Diagrams (SLDs) Are Generated

The Electrical Single-Line Diagram illustrates the flow of power through the system.

4. Equipment Specifications Are Attached

Inverters, optimizers, panels, disconnects, and metering equipment.

5. Utility Forms Are Completed

Each utility has unique interconnection applications, fees, and review steps.

6. Utility Engineers Review the Package

They verify compatibility with service ratings, transformer capacity, and grid stability.

7. Approval → Installation → PTO

After approval, the solar system is built, inspected, and granted Permission to Operate.

Types / Variants of Interconnection Documents

1. Residential Interconnection Package

Simplified, includes SLD, panel schedule, inverter spec sheet, and site plan.

2. Commercial Interconnection Package

More complex: often includes load studies, transformer coordination, and protection requirements.

3. Utility-Scale Interconnection Package

Includes advanced studies such as:

• Power flow impact analysis
• Short-circuit contribution studies
• Voltage regulation evaluation
• Protection coordination

4. Fast-Track Interconnection (Small Systems)

Utilities may offer simplified approvals for low-impact systems.

5. Supplemental Studies Documentation

Triggered when a project exceeds initial grid capacity limits.

How Interconnection Documents Are Measured

Interconnection documents are evaluated not by numerical metrics, but by:

Completeness

Missing drawings or spec sheets can delay approvals.

Accuracy

Electrical mismatches or outdated equipment data cause rejections.

Code Compliance

Must align with NEC 690, utility rules, and local fire codes.

Grid Impact Assessment

Evaluated for backfeed potential, transformer overload, and stability.

Safety Criteria

Disconnect placement, rapid shutdown, and grounding.

Typical Requirements / Ranges

Practical Guidance for Solar Designers & Installers

1. Align design software outputs with utility templates

Use SurgePV tools to generate accurate layouts and diagrams.

2. Always verify equipment models

Utilities reject mismatched inverter or panel specifications.

3. Include clear AC and DC wiring details

Ensure consistency with the Stringing & Electrical Design.

4. Show proper disconnect and meter placement

Avoid common failures caused by unclear equipment locations.

5. Document shading and performance assumptions

Helps utilities validate realistic production expectations.

6. Keep all documents consistent

SLDs, site plans, and equipment lists must match exactly.

7. Use clearly labeled drawings

Clarity reduces review time.

Real-World Examples

1. Residential Rooftop Solar Application

A designer uploads a 7 kW layout and generates an SLD, site plan, and inverter spec sheets. The utility approves within 10 days because all documents were clean and consistent.

2. Commercial Interconnection Submission

A 250 kW flat-roof system includes load studies, a detailed three-line diagram, and a transformer coordination report. The utility requests minor clarifications but approves without requiring supplemental studies.

3. Utility-Scale Solar Farm

A 20 MW project submits a full interconnection package including power flow modeling, protection schemes, and sectionalized switchgear diagrams. After iterative review, the utility grants conditional approval pending on-site testing.

• Interconnection Agreement
• Stringing & Electrical Design
• Solar Inverter
• Electrical Single-Line Diagram
• Mounting Structure