Roof Shading Report

A Roof Shading Report is a detailed solar assessment that quantifies how nearby obstructions—such as trees, neighboring buildings, chimneys, dormers, parapets, antennas, and surrounding terrain—block sunlight on a roof throughout the year. It provides hour-by-hour and month-by-month shading data that solar professionals use during solar designing to optimize panel placement, maximize energy generation, and prevent long-term system underperformance.

This report plays a foundational role in modern solar project planning and analysis because shading directly impacts annual energy yield, solar layout optimization, inverter sizing, and system financials. Accurate shading analysis reduces redesign cycles, strengthens customer confidence, and supports compliant engineering documentation for residential, commercial, and utility-scale projects.

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Key Takeaways

Roof Shading Reports quantify how obstructions affect solar access.
They directly impact layout, energy estimates, and financial modeling.
Accurate shading analysis improves proposal quality and system reliability.
Advanced 3D reports provide essential module-level insights.
Solar Access %, TSRF, and hourly shading curves are core decision metrics.

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What It Is

A Roof Shading Report is a structured technical document—typically generated using solar design software or professional site-assessment tools—that clearly outlines:

When shading occurs on a roof
Where shading impacts specific module locations
How much sunlight is lost over time
The performance impact on each array zone

It also includes critical performance indicators such as Solar Access (%), TSRF (Total Solar Resource Fraction), and hourly sun availability values.

Design teams rely on this report to validate system feasibility, refine solar layout optimization, perform accurate shadow analysis, and improve downstream stringing & electrical design decisions.

How It Works

A Roof Shading Report is created by digitally reconstructing the site and simulating the sun’s movement across the sky for an entire year.

1. Site Data Collection

The process begins by capturing accurate site inputs such as:

Roof geometry, tilt, and azimuth
Nearby obstructions and their heights
Data sources including satellite imagery, LiDAR, drone scans, or on-site measurements

This data forms the foundation for professional solar designing and production modeling.

2. 3D Scene Reconstruction

Using the collected data, software builds a precise 3D model of the roof and surroundings, defining:

Obstruction positions and shapes
Roof planes and usable areas
Setbacks and mounting constraints

This step is critical for accurate mounting structure planning and layout validation.

3. Solar Path Simulation

The system simulates the sun’s position for every hour of the year using:

Solar azimuth
Solar elevation
Seasonal sun paths

Designers often reference tools like the Sun Angle Calculator to validate assumptions and improve confidence in shading projections.

4. Shading Metrics Generation

From the simulation, the software generates:

Annual Solar Access (%)
TSRF (Total Solar Resource Fraction)
Hourly and monthly shading curves
Module-level shading heatmaps

These outputs directly influence performance ratio calculations and long-term energy forecasts.

5. Report Compilation

All results are compiled into a professional Roof Shading Report used in:

solar proposals
Engineering and permitting packages
AHJ and utility submissions

Types / Variants

1. Basic Shading Report

Uses 2D imagery only
Monthly averages without module-level detail
Suitable for early-stage quoting by solar installers

2. Advanced 3D Roof Shading Report

Full 3D modeling with object profiles
Module-level shading precision
Ideal for engineering-grade solar project planning

3. On-Site Solar Pathfinder / Sun-Eye Report

Generated using handheld measurement devices
Useful when aerial data is outdated or obstructed

4. Utility-Grade Shading Study

Uses LiDAR or drone photogrammetry
Required for large commercial and utility-scale systems

How It’s Measured

A Roof Shading Report relies on standardized solar performance metrics.

Solar Access (%)

Measures the percentage of unshaded sunlight reaching a location compared to an unobstructed reference.

Formula:

Solar Access % = (Unshaded Irradiance ÷ Total Possible Irradiance) × 100

TSRF (Total Solar Resource Fraction)

TSRF combines:

Shading losses
Roof tilt
Roof azimuth

to represent overall site quality for PV deployment.

Hourly Shading Values

Provides hour-by-hour shading percentages across a typical meteorological year—essential for accurate generation modeling.

Obstruction Angles

Vertical angles (0°–90°) measured across azimuth directions to quantify obstruction severity.

Practical Guidance

For Solar Designers

Always run shading analysis before finalizing layouts.
Use shading heatmaps to refine solar layout optimization and MPPT grouping.
Validate results with site visits when trees or future construction may impact access.

For Installers

Use reports during site surveys to confirm trimming or obstruction mitigation.
Pair shading visuals with roof pitch calculator outputs for accurate installs.

For EPCs & Developers

Include Roof Shading Reports in permitting and financing packages.
Cross-check generation values using generation & financial tools.

For Sales Teams

Embed shading visuals into solar proposals to clearly explain performance and ROI.
Support savings discussions with the solar ROI calculator.

Real-World Examples

Residential Example

A south-facing roof experiences afternoon tree shading. The Roof Shading Report shows Solar Access dropping to 84% in one zone. Designers adjust array placement and recommend trimming, increasing annual production by 11%.

Commercial Example

HVAC units cast moving shadows across a warehouse roof. Module-level shading maps identify >20% loss zones, allowing designers to reroute stringing & electrical design and prevent mismatch losses.

Utility-Scale Example

Terrain shading affects early-morning winter production on a 2 MW site. Row spacing and tilt are adjusted, improving annual yield projections and bankability.

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Releated Terms

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