Shading Analysis
The engineering process of calculating how obstructions such as trees, chimneys, HVAC units, and neighboring buildings cast shade on a PV array through the year, then quantifying the resulting loss in energy yield so the array can be laid out to minimize it.
A shading analysis models how direct and diffuse light reaches a PV array over a year, accounting for every obstruction that could block it. The output is a time-resolved production estimate, usually hourly, that captures the yield penalty from shade on individual modules, strings, or the full array.
The analysis combines three inputs: the site's coordinates and local sun path, a 3D model of the surroundings (tree canopies, chimneys, HVAC units, walls, neighboring roofs), and the PV layout itself. Modern tools render shadows at hourly intervals across a typical meteorological year and convert them into kWh losses using each module's electrical behavior under partial shading.
The output matters most in two places: system sizing and proposal credibility. An optimistic study oversizes the array and inflates the quoted production. A too-conservative one loses the deal to competitors. Both outcomes hurt.
Why it matters for solar installers
Shading analysis is where 3D design pays for itself. solarVis' design canvas models obstructions in 3D, casts shadows across the full year, and feeds the loss calculation directly into the proposal's yield and payback numbers, so the figure on the proposal is the figure the customer can trust.
Common questions
- How accurate does a shading analysis need to be?
- Accurate enough that your proposal's production estimate holds up once the system is built. A 5 percent error on a 10 kW residential system is roughly 500 kWh per year, which becomes real money over 25 years and a real credibility hit if the system underperforms.
- What's the difference between a horizon-based and a 3D shading study?
- Horizon-based tools assume a single horizon profile and miss small, close-in obstructions like chimneys. 3D tools model the actual surroundings and cast true shadows at hourly intervals, capturing partial shading that triggers bypass diodes in the inverter.
- Do I need a shading analysis on every rooftop project?
- On a clean roof with no nearby obstructions, a simplified check is enough. For any site with a tree line, dormer, or neighboring building within a couple of roof heights, a full hour-by-hour study pays for itself in avoided under or over sizing.
