Roof Segmentation

Roof Segmentation is the process of dividing a building’s roof into distinct sections based on geometry, slopes, orientations, obstructions, and structural boundaries. In professional solar designing, this step is critical because it determines how solar panels are placed, how solar shading analysis is evaluated, how strings are configured, and how accurate energy modeling is performed.

A clean roof segmentation is one of the first foundational steps in producing a reliable solar layout. Without proper segmentation, workflows such as Solar Layout Optimization, shading analysis, mounting structure planning, and Bill of Materials (BOM) creation become inaccurate or inefficient—leading to design errors and cost overruns.

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• Roof segmentation is the foundation of accurate solar design.
• Each segment must maintain consistent tilt, azimuth, and boundaries.
• It improves shading accuracy, layout precision, and energy modeling.
• Enables Auto-Design to produce code-compliant, high-performance layouts.
• Reduces installation risk and improves financial projections.

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What It Is

Roof segmentation breaks a roof into workable areas—called roof segments—based on shape, tilt, orientation, and usable surface. Each segment acts as its own design zone, enabling precise placement of modules, spacing, racking systems, and electrical routing during solar layout optimization.

A roof segment typically represents:

• A uniform pitch
• A uniform azimuth
• An obstruction-free zone
• A code-compliant surface that meets AHJ compliance, fire setbacks, and array boundary tool constraints

When used inside modern design platforms and workflows such as Auto-Design, segmentation ensures each roof face is evaluated independently—maximizing accuracy in both layout and energy yield.

How It Works

Roof segmentation follows a structured workflow used by professional solar designers, installers, and EPCs:

1. Identify Roof Geometry
2. Detect ridges, hips, valleys, dormers, parapets, and edges using aerial imagery or site data during solar designing.
3. Apply Setbacks & Safety Clearances
4. Enforce fire access and structural rules based on AHJ requirements and local building codes.
5. Divide Surfaces Into Segments
6. Each segment is defined by a consistent tilt and azimuth for accurate energy modeling.
7. Remove Obstructed Zones
8. Exclude chimneys, vents, skylights, HVAC units, and satellite dishes from usable areas.
9. Create Array-Ready Zones
10. These zones become eligible for module placement in solar panel sizer and layout tools.
11. Run Shadow Analysis
12. Each roof segment is evaluated independently using Shadow Analysis to capture segment-level shading losses.
13. Optimize Panel Placement
14. Segments feed directly into Auto-Design, stringing & electrical design, and inverter sizing workflows.

This structured segmentation ensures every array respects roof boundaries, fire setbacks, and shading behavior—reducing downstream design errors.

Types / Variants

1. Geometric Segmentation

Divides the roof purely by structural planes—tilt changes, direction changes, and physical roof lines.

2. Obstruction-Based Segmentation

Creates segments around roof obstructions to prevent shading and installation conflicts.

3. Code-Driven Segmentation

Defines usable zones based on AHJ compliance, fire pathways, and setback regulations.

4. Optimization-Based Segmentation

Software- or AI-driven segmentation used in Auto-Design to maximize energy output and layout efficiency.

How It’s Measured

Roof segmentation relies on measurable design inputs that directly affect system performance:

AttributeDescriptionPitch (°)Tilt angle of each segment (commonly validated using the Roof Pitch Calculator).Azimuth (°)Orientation relative to true south, refined using the Sun Angle Calculator.Usable AreaNet installable surface after setbacks and obstructions.Shading Factor (%)Annual shading loss calculated per segment using Shadow Analysis.Load-Bearing CapacityConfirms structural support for the mounting structure and modules.

Accurate measurements here directly impact performance ratio and production forecasts.

Practical Guidance (Actionable Steps)

For Solar Designers

• Always perform roof segmentation before starting solar layout optimization.
• Validate pitch and azimuth carefully—errors propagate into yield calculations.
• Run Shadow Analysis for every segment to avoid underperforming placements.
• Use Auto-Design only after segmentation is finalized.

For Installers & EPCs

• Confirm segmented areas during site visits, especially for complex roofs.
• Choose segments with simple mounting structure requirements.
• Flag segments needing special attachments or flashing early in the design.

For Sales Teams

• Use segmented roof visuals in solar proposals to clearly explain system layout.
• Show how segment-level shading affects savings and ROI using the Solar ROI Calculator.

For Developers & Large Projects

• Segment flat roofs by parapets, mechanical clusters, and wind zones.
• Use Solar Layout Optimization to group segments for maximum yield.
• Validate electrical losses with Voltage Drop Calculator and AC Size Calculator.

Real-World Examples

Residential Example

A gable roof is divided into south-, east-, and west-facing segments. Solar Layout Optimization prioritizes the south-facing segment, delivering the highest annual production.

Commercial Example

A warehouse roof with HVAC units uses obstruction-based segmentation to define five clean zones. Designers use Auto-Design to populate these zones with uniform racking.

Utility-Scale Rooftop

Multiple industrial buildings with varying tilts are segmented individually. This improves total system output and reduces cable losses through optimized Stringing & Electrical Design.

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• Solar Layout Optimization
• Array Boundary Tool
• Auto-Design
• Bill of Materials (BOM)
• Stringing & Electrical Design
• Mounting Structure
• Performance Ratio

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