Solar Shading Analysis Tool
Free solar shading analysis tool. Enter location and nearby obstructions to get annual shading loss, monthly breakdown, sun path sky dome, and de-rating recommendations. No signup.
Solar Shading Analysis Tool
Select your location, tilt, and shading description. Get shading loss factor, annual production with and without shading, kWh lost, and a remediation recommendation.
Add trees, chimneys, or buildings that cast shadows on your array. For each, estimate its height angle (how high it looks above the horizon from your array) and horizontal spread (how wide it looks in the sky).
Enter your site location to see the sun path diagram with shading overlays for your specific latitude.
This is a simplified geometric estimate. SurgePV's platform uses LiDAR elevation data, satellite imagery, and 3D ray tracing to give panel-by-panel shading loss with hourly precision - without any manual input.
Book a Free Demo for Full LiDAR Analysis →Monthly shading loss chart will appear here after entering your location.
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What This Tool Covers
This shading analysis tool estimates the impact of shading on solar array production. Enter your location, array orientation, and shade description to get a shading loss factor, annual kWh lost, and dollar value of that loss - without needing full design software.
Inputs Required
- • State or location (for irradiance data)
- • Array azimuth (degrees from south)
- • Array tilt angle (degrees)
- • Shade level: none / partial / moderate / heavy
- • Shading source type (trees, buildings, etc.)
- • Percentage of array affected by shading
- • Unshaded annual production (kWh)
Outputs Provided
- • Shading loss factor (%)
- • Annual production with shading (kWh)
- • Annual production without shading (kWh)
- • kWh lost annually due to shading
- • Dollar value of annual production loss
- • 25-year cumulative loss estimate
- • Mitigation recommendation
Features
State-Level Irradiance Data
Uses state-average peak sun hour data to calibrate shading loss estimates to your actual solar resource - not a generic national average.
Shade Source Classification
Differentiate between shading from trees, adjacent buildings, chimneys, or HVAC equipment - each has a different seasonal and time-of-day loss profile.
Mitigation Recommendations
Outputs actionable recommendations - microinverters, DC optimizers, panel relocation, or tree trimming - based on the shade level and source type entered.
How It Works
Select Your State
Choose the installation state to load the appropriate average peak sun hours and irradiance profile for that location.
Enter Array Orientation
Input the azimuth (0 = south, negative = east, positive = west) and tilt angle. These affect when during the day shading occurs and how much production is lost.
Describe the Shading
Select a shade level (none/partial/moderate/heavy), the type of shading source, and estimate what percentage of the array is affected during peak hours.
Enter Unshaded Production
Enter the system's expected annual production without shading (from your design software or PVWatts) so the tool can calculate the absolute kWh and dollar loss.
Review Shading Impact Report
Get the shading loss factor, adjusted annual production, annual kWh and dollar loss, 25-year cumulative impact, and a recommendation for mitigation.
Use Cases
Pre-Design Site Qualification
Quickly determine whether a shaded site is worth pursuing before investing time in a full design. If the loss is above 20%, the conversation shifts to mitigation options or alternative placement.
Customer Education on Shading
Show customers the dollar cost of shading over 25 years in plain language. A $450/year loss becomes an $11,250 lifetime impact - a clear case for tree trimming or optimizer technology.
Justifying Optimizer or Microinverter Upsell
Use the shading loss output to calculate payback on DC optimizers or microinverters. If the upgrade costs $800 and recovers $300/year in lost production, the payback is under 3 years.
Calculation Methodology
Shading losses are modeled using established loss factor ranges from NREL and PVsyst research, adjusted for array orientation and shading source type.
Shade Level Loss Factors
None: 0–1% · Partial: 3–8% · Moderate: 9–18% · Heavy: 19–35%
Loss factors are assigned per shade category and scaled by the percentage of array affected and source type.
Annual kWh Lost
kWh Lost = Unshaded Production × Shading Loss Factor
Applies the shading loss factor to the unshaded annual production figure to compute the absolute energy penalty.
Annual Dollar Loss
Dollar Loss = kWh Lost × Local Utility Rate ($/kWh)
Converts kWh loss to a dollar figure using the customer's current utility rate, making the impact concrete and financial.
25-Year Cumulative Loss
Lifetime Loss = Annual Loss × ∑ Rate Escalation Factor (25 years)
Projects the dollar loss over 25 years with a 3% annual utility rate escalation to show the long-term cost of unaddressed shading.
Pro Tips
Morning shading is less costly than afternoon shading. Solar irradiance peaks between 10 AM and 2 PM. A tree on the east side that shades early morning is far less damaging than a chimney or west-facing obstruction that hits during peak hours.
String inverter shading losses are disproportionate. On a standard string inverter, one shaded panel can reduce output of the entire string by 20–50%. DC optimizers or microinverters limit this to only the shaded panel, typically recovering 60–80% of the shading loss.
The 80% rule: avoid sites with more than 20% shading loss. Below that threshold, mitigation technology usually makes the system viable. Above 20%, the economics often don't work even with optimizers unless the utility rate is very high.
Always check winter sun angles. A tree that causes no shading in July can shade a south-facing array by 30% in December when sun angles are low. Use the roof pitch and azimuth inputs to assess worst-case seasonal shading.
Frequently Asked Questions
How much does shading reduce solar panel output?
Light partial shading on a small portion of the array causes 3–8% annual production loss. Moderate shading from nearby trees or buildings typically causes 9–18% loss. Heavy shading for several hours per day can reduce annual output by 20–35% or more.
Can microinverters eliminate shading losses?
Microinverters minimize string-level losses but do not eliminate individual panel losses from direct shading. A shaded panel still produces less. Microinverters ensure the unshaded panels in the array operate at full power rather than being dragged down by the shaded panel.
What is a shading loss factor?
A shading loss factor is the percentage of potential annual production lost due to shading. A 10% shading loss factor means the system produces 10% less electricity per year than it would on a fully unshaded roof with the same orientation.
Should I install solar on a shaded roof?
It depends on the degree of shading and the local utility rate. Sites with under 10% shading loss are generally viable without mitigation. Sites with 10–20% loss benefit from DC optimizers or microinverters. Sites with more than 20% loss should be evaluated case by case - in high-rate states, they may still pencil out.
How is shading different from soiling or snow losses?
Shading is caused by physical objects blocking sunlight from reaching panels. Soiling is dirt, dust, or bird droppings on the panel surface. Snow covers panels temporarily in winter. This tool models shading only - soiling and snow are separate derate factors typically applied in full design software.
Does azimuth affect shading impact?
Yes. An east-facing array receives most of its production in the morning. If shading occurs in the morning from a nearby building, it hits the array during its primary production window. A south-facing array is most sensitive to shading between 10 AM and 2 PM, while a west-facing array is most sensitive in the afternoon.
Ready to Fix Shading and Build the Optimal Solar Design?
SurgePV goes from shading analysis to a complete optimized solar design - with string-level shading reports, production modeling, financial analysis, and proposals in one platform.
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