A lab experiment covering 20% of a solar cell’s area recorded a power loss of 11.6% for that module. This kind of partial shading — from things like chimneys, trees, or vents — can significantly undermine production if not carefully analyzed.
Solar panel shading analysis gives installers the insight to quantify how obstructions will affect energy generation throughout the year, not just at the moment of installation. It’s the difference between over-promising on ROI and actually delivering close to modeled performance.
This blog explains what shading analysis involves, how shading patterns impact yield, compares digital and on-site assessment tools, and provides a practical checklist that every installer can use to minimize risk.
Basics of Solar Panel Shading Analysis in Installations
Shading assessment starts with understanding how sunlight moves across the site throughout the day and across different seasons. Installers need clarity on when and where shadows appear, which objects cause them, and how long they persist. This foundation ensures that production estimates reflect real operating conditions instead of ideal or static assumptions.
Common shading sources include:
Tree canopies
Chimneys and vents
Parapet walls
Neighboring buildings
Utility poles and wires
Satellite dishes, railings, and other rooftop obstructions
A basic solar panel shading analysis should confirm:
Where shading falls on the roof or ground-mount area
How long shading persists at different times of the year
Which modules, strings, or MLPE devices are affected during shaded periods
Why Does It Matter?
Accurate solar panel shading analysis matters because it reduces layout errors, prevents inflated energy projections, and minimizes redesigns during plan set review or permitting. It also supports stronger customer communication by showing how shading influences long-term system output and expected ROI.
Shading Loss: What Installers Need to Calculate
Shading loss is the reduction in energy production that occurs when part of a module receives less sunlight than the rest of the array. Even small shaded areas can influence output depending on cell configuration, bypass diodes, and whether the system uses string inverters or MLPE (Module-Level Power Electronics).
Key Factors Installers Should Calculate:
Duration of shading throughout the day and across seasons
Percentage of the module affected (cell-level, row-level, or full-module shading)
Time of day the shading occurs, since morning and afternoon losses impact production differently
Impact on the string, including whether one shaded module affects others upstream or downstream
Equipment behavior, such as how MLPE mitigates or isolates shaded modules
Digital vs. On-Site Solar Panel Shading Analysis Methods
Solar panel shading analysis is done through a combination of digital modeling and field measurements. Most installers rely on both because each method captures different details that influence final system performance. Digital tools help with early-stage planning and layout decisions, while on-site assessments validate real-world conditions that satellite imagery or software cannot fully capture.
Digital Shading Assessment
Uses satellite imagery, 3D models, and historical sun-path data
Helps identify year-round shading patterns before visiting the site
Useful for estimating solar access, roof suitability, and preliminary array placement
Tools like Aurora Solar, Helioscope, and PVsyst generate shade reports and production estimates
Fast, repeatable, and ideal for proposal and design stages
On-Site Shading Assessment:
Confirms actual shading using field tools such as SunEye, Solmetric devices, drones, or lidar-enabled measurements
Captures obstruction height, distances, and horizon profiles with higher accuracy than satellite data
Records real-time conditions including nearby trees, vents, railings, and rooftop irregularities
Essential for detecting shading sources not visible in aerial imagery
Provides the most reliable data for final design and plan set development
Solar Panel Shading Analysis Checklist for Installers
Here is a compact, field-ready checklist that installers can use as a sequence of actions plus the specific measurements and deliverables to record at each step:
Pre-survey (desktop prep)
Review site address in mapping software and note roof geometry, nearby trees/buildings, and any obvious obstructions.
Pull recent aerial/satellite imagery and compare year-over-year (to spot tree growth).
Run a preliminary sun-path or shading simulation to flag high-risk areas before the visit.
Prepare equipment list: measuring tape, laser rangefinder, smartphone with camera/GPS, clinometer/tilt tool, SunEye or equivalent, ladder/PPE, and drone (if used).
On-site data capture
Record site metadata: address, GPS coordinates, roof azimuth(s), roof pitch(s), and module layout sketch.
Photograph every roof plane and suspected obstruction from multiple angles. Ensure photos include scale (tape, person) and timestamp/GPS.
Measure and record obstruction details: type, height above roof plane, distance from array edge, and azimuth relative to the array.
Capture horizon profile and sky-visibility (SunEye, Solmetric, or lidar/drone-derived horizon).
Note seasonal considerations: deciduous trees, planned landscaping or construction nearby, and roof features that may change (satellite dishes, HVAC units).
For ground-mount sites, measure site grading, nearby vegetation heights, and fence/structure placements.
Modeling & analysis
Import field data and photos into your shading/modeling tool (Aurora, Helioscope, PVsyst, etc.).
Run annual production models including seasonal extremes and worst-case shading scenarios.
Map which modules and strings are affected and identify if MLPE (microinverters/optimizers) is recommended to mitigate impact.
Produce a quantified loss estimate (annual kWh and percentage loss) and document the assumptions used (albedo, module model, inverter clipping, system losses).
Design decisions & documentation
Propose layout changes to reduce shading impact (module relocation, string reconfiguration, use of MLPE, trimming/removal options).
Create a clear shading report page for the plan set—include photos, horizon plot, annotated layout, loss estimate, and recommended mitigations.
Add a short client-facing summary that states expected production, key shading risks, and any recommended actions (tree trimming, MLPE, alternate layout).
Archive raw data (photos, SunEye files, measurement logs) for future reference and permitting queries.
Data & deliverables to produce
Site metadata sheet (coordinates, azimuths, pitches)
Photo pack with captions and timestamps
Horizon/sky-visibility plots or SunEye files
Modeled energy yield with shading loss summary (kWh/year and % loss)
Annotated plan set page showing shaded modules and recommendations
Client summary / sign-off page noting assumptions and recommended mitigations
Field notes & best practices
Always verify satellite imagery against on-site photos—trees and small structures often change.
Take photos from the same vantage points you’ll use in the report; labeled photos speed approvals.
When in doubt about seasonal shading, document the worst-case (winter sunrise/sunset) and state it in assumptions.
Record who authorized any recommended shading removals (customer/property owner) and include this in the report.
Keep a consistent naming convention for files so survey data links directly to the plan set and permitting packet.
Key Takeaways for Better Solar Panel Shading Analysis
Effective solar panel shading analysis starts with understanding how sunlight moves across the site and how nearby structures influence available solar access throughout the year. Installers who document shading accurately during the survey stage reduce the risk of redesigns, rejected permit plans, and customer escalations.
Digital modeling provides a strong early estimate, but on-site verification remains essential for capturing real conditions that satellite imagery often misses. The most reliable results come from combining both methods and reviewing how shading affects each module, string, and inverter configuration.
Accurate solar panel shading analysis also improves production modeling, supports transparent communication with customers, and ensures that financial projections closely match real performance. When installers consistently measure obstruction height, distance, duration, and seasonal behavior, shading becomes a predictable design input instead of a cause of unexpected system losses.
