Solar Pathfinder

A Solar Pathfinder is a site assessment tool used by solar installers to evaluate shading at a proposed panel location throughout the entire year without needing to visit the site in every season. The original device uses a transparent convex dome that reflects the surrounding skyline — trees, buildings, terrain — onto a sun-path diagram underneath, revealing exactly when and where shade will fall on the panels during every hour of every month.

The installer places the Solar Pathfinder at the proposed panel location and photographs the dome reflection. The reflected skyline is overlaid on sun-path arcs printed on the diagram below. Where obstructions intersect a sun-path arc, the panels will be shaded during that time period. The resulting image gives a complete annual shading profile from a single snapshot taken on a single visit.

Modern shade analysis has largely transitioned to digital tools. The Solar Pathfinder company offers a digital version with software that calculates precise percentage losses from the photographic analysis. Other tools like the Solmetric SunEye, Aurora Solar's satellite-based shade modeling, and smartphone apps using LiDAR (on newer iPhones and Android devices) provide similar shade assessment capabilities.

Accurate shade analysis is critical for system design because even small amounts of shading can dramatically reduce output — especially in string inverter configurations where shaded panels drag down the entire string. Knowing the exact shade windows helps designers decide between string inverters, microinverters, or power optimizers and informs panel placement to avoid the worst shade zones.

Any reputable solar installer will perform a shade analysis before designing your system. If an installer skips this step, consider it a red flag — shade is the most common cause of underperforming residential solar systems.