Key Takeaways
- A shade report documents shading losses for every panel position across all hours of the year
- Required by many jurisdictions for permit applications and incentive program eligibility
- Typically includes solar access percentages, obstruction profiles, and monthly loss breakdowns
- Generated using tools like sun path diagrams, fisheye lens cameras, or 3D modeling software
- Shading losses of even 5–10% can significantly affect system ROI and payback period
- Modern software automates shade report generation from 3D site models
What Is a Shade Report?
A shade report is a formal document that quantifies how much shading affects a solar installation site. It maps out exactly which obstructions (trees, buildings, chimneys, vents, neighboring structures) cast shadows on the proposed panel locations, when those shadows occur, and how much energy production is lost as a result.
Unlike a general site assessment, a shade report provides specific numbers: solar access percentages for each panel position, monthly shading loss breakdowns, and annual production impact estimates. This data feeds directly into system design decisions, financial projections, and permit applications.
A shade report transforms shading from a vague concern into a precise, quantified design input. Without one, you’re guessing at losses — and guesses don’t belong in customer proposals.
Components of a Shade Report
A complete shade report includes several standardized sections that document shading conditions at the site.
Site Information
Location coordinates, roof orientation, tilt angle, and compass bearing. Establishes the geographic and geometric context for all shading calculations.
Obstruction Identification
A catalog of all shading obstructions — trees (with species and expected growth), buildings, chimneys, HVAC units, power lines, and terrain features — with their heights and distances from the array.
Sun Path Diagram
A graphical representation of the sun’s path across the sky throughout the year, overlaid with obstruction profiles. Shows exactly when each obstruction casts shadows on the array.
Solar Access Values
Percentage of available solar energy that reaches each panel position after accounting for shading. A solar access of 95% means 5% of potential energy is blocked by obstructions.
Monthly Loss Breakdown
Shading losses calculated for each month, showing seasonal variation. Winter losses are typically highest due to low sun angles and long shadows from obstructions.
Annual Production Impact
The total estimated energy loss from shading, expressed as both kWh and percentage of unshaded production. This figure directly reduces the production estimate used in financial modeling.
Annual Shading Loss (kWh) = Unshaded Production (kWh) × (1 − Solar Access %)Methods for Creating Shade Reports
Different tools and techniques produce shade reports with varying levels of accuracy, cost, and convenience.
3D Software Modeling
Software like SurgePV’s shadow analysis tool builds a 3D model of the site and simulates sun positions throughout the year. Produces hour-by-hour shading data for every panel position automatically.
Solar Pathfinder / Fisheye Camera
A dome-shaped device or fisheye lens photograph captures the horizon profile at the panel location. Software analyzes the image to calculate solar access. Requires physical site visits.
LiDAR / Satellite Data
Aerial LiDAR scans or satellite imagery provide 3D surface data for shading analysis without a site visit. Accuracy depends on data resolution and currency. Trees may not be fully captured.
Manual Sun Path Analysis
Using a compass and inclinometer to measure obstruction angles, then plotting on a sun path chart. Time-consuming and less precise, but requires no specialized equipment.
Software-based shade reports from solar design software are increasingly accepted by AHJs (Authorities Having Jurisdiction) in place of field-measured reports. However, some rebate programs still require on-site measurement. Check local requirements before relying solely on remote analysis.
Key Metrics & Calculations
A shade report communicates shading impact through several standardized metrics.
| Metric | Unit | What It Measures |
|---|---|---|
| Solar Access | % | Percentage of available solar energy reaching the panel after shading |
| Total Solar Resource Fraction (TSRF) | % | Solar access × tilt/orientation factor — overall resource available |
| Annual Shading Loss | kWh or % | Energy production lost to shading per year |
| Monthly Shading Factor | % per month | Shading loss broken down by calendar month |
| Weighted Solar Access | % | Solar access weighted by irradiance — gives more weight to high-production hours |
| Shade-Free Window | hours | Minimum daily unshaded hours (often defined as 10 AM – 2 PM solar time) |
TSRF (%) = Solar Access (%) × Tilt & Orientation Factor (%)Practical Guidance
Shade reports serve different purposes for designers, installers, and sales teams. Here’s how each role uses them.
- Generate shade reports early in the design process. Run shading analysis using solar design software before finalizing panel layout. Moving panels to avoid shade is far cheaper than accepting production losses for 25 years.
- Exclude heavily shaded positions. Any panel position with solar access below 80% typically hurts system economics. Consider removing those panels or repositioning them rather than including them in the array.
- Account for future shading changes. Trees grow, buildings may be constructed nearby. Document current tree heights and growth rates, and note any adjacent vacant lots that could be developed.
- Use shade data to select inverter topology. Sites with partial shading benefit from microinverters or power optimizers, which mitigate the disproportionate impact of shading on series-connected string inverter systems.
- Verify shade report on-site before installation. Compare the shade report’s obstruction list against actual site conditions. New HVAC units, tree growth, or neighbor construction may have changed the shading profile since the report was created.
- Include the shade report in the permit package. Many AHJs require shade reports as part of the solar permit application. Ensure the report format meets local requirements before submission.
- Discuss tree trimming with the customer. If the shade report identifies tree shading as a significant loss factor, discuss trimming options before installation. Get written agreement to avoid post-install disputes.
- Archive the shade report with project files. Keep the original shade report for warranty and performance dispute resolution. It establishes the baseline conditions under which production estimates were made.
- Use shade reports to build credibility. Showing customers a detailed shade report demonstrates engineering rigor. It differentiates your company from competitors who just “eyeball” the roof and quote a price.
- Present shade data visually. Solar access heat maps and sun path diagrams are more persuasive than tables of numbers. Use solar software to generate visual shade reports for customer presentations.
- Address shading concerns proactively. If a customer’s neighbor has tall trees, acknowledge the shading impact upfront with data. This builds trust and prevents post-installation complaints about lower-than-expected production.
- Explain the financial impact of shading. Translate shade report data into dollar terms. “This tree causes 8% shading loss, reducing your annual savings by approximately $180” is more meaningful than “92% solar access.”
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SurgePV’s automated shadow analysis creates detailed shade reports from 3D site models — no site visit needed for initial assessment.
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Real-World Examples
Residential: South-Facing Roof with Chimney
A 7 kW residential system in Connecticut shows 97% solar access for 18 of 20 panels. Two panels near the chimney drop to 78% and 82% solar access during winter months. The shade report recommends removing those two panels, reducing system size to 6.3 kW but increasing the overall solar access average from 94.2% to 97.1%. Annual production improves by an effective 3.8% per kW installed.
Commercial: Multi-Story Building with Rooftop Equipment
A 100 kW commercial rooftop in Chicago has HVAC units, exhaust stacks, and a parapet wall creating complex shading patterns. The shade report generated using solar shadow analysis software identifies that 15% of the proposed panel area has solar access below 85%. Redesigning the layout to avoid these zones reduces the system to 82 kW but increases specific yield (kWh/kWp) by 11%.
Residential: Tree Shading — Before and After Trimming
A homeowner in Oregon receives a shade report showing 86% average solar access due to two large oak trees on the south side. After selective trimming (reducing tree height by 15 feet), a revised shade report shows solar access improving to 95%. The production increase of 850 kWh/year at $0.12/kWh adds $102/year in savings — paying for the $600 tree trimming cost in under 6 years.
Impact on System Design
Shade report data directly influences several system design decisions.
| Design Decision | Without Shade Report | With Shade Report |
|---|---|---|
| Panel Placement | Fill available area uniformly | Avoid positions below solar access threshold |
| String Configuration | Standard series strings | Arrange strings to isolate shaded panels |
| Inverter Selection | String inverter default | Microinverters/optimizers for partially shaded sites |
| Production Estimate | Overstated by 5–20% | Accurate, defensible projections |
| Financial Projections | Unrealistic ROI | Conservative, trustworthy numbers |
Set a minimum solar access threshold for your designs. A common industry standard is 80% annual solar access. Panels below this threshold often cost more in production losses over 25 years than the revenue they generate. Use SurgePV’s shadow analysis to identify and exclude low-access positions automatically.
Frequently Asked Questions
What is a shade report for solar panels?
A shade report is a detailed document that measures and quantifies how much shading affects a solar panel installation site. It identifies all shading obstructions (trees, buildings, chimneys), calculates the percentage of solar energy blocked throughout the year, and estimates the resulting production losses. This information is used to optimize panel placement and generate accurate financial projections.
How much shading is too much for solar panels?
Most solar professionals set a minimum threshold of 80% annual solar access. Panel positions below this level typically generate less financial return than their proportional share of system cost. However, with microinverters or power optimizers, partially shaded panels don’t drag down the entire string, making some shading more manageable. The shade report helps you make this determination with data rather than guesswork.
Is a shade report required for solar permits?
Requirements vary by jurisdiction. Many U.S. states and municipalities require shade reports as part of the solar permit application, especially for systems receiving state or utility rebates. Some incentive programs set minimum solar access thresholds (e.g., 75% or 80%) that must be documented in a shade report. Even where not required, shade reports are considered best practice for professional solar installations.
About the Contributors
CEO & Co-Founder · SurgePV
Keyur Rakholiya is CEO & Co-Founder of SurgePV and Founder of Heaven Green Energy Limited, where he has delivered over 1 GW of solar projects across commercial, utility, and rooftop sectors in India. With 10+ years in the solar industry, he has managed 800+ project deliveries, evaluated 20+ solar design platforms firsthand, and led engineering teams of 50+ people.
Content Head · SurgePV
Rainer Neumann is Content Head at SurgePV and a solar PV engineer with 10+ years of experience designing commercial and utility-scale systems across Europe and MENA. He has delivered 500+ installations, tested 15+ solar design software platforms firsthand, and specialises in shading analysis, string sizing, and international electrical code compliance.