Shading Analysis explained
A shading analysis evaluates how much of your roof is affected by shadows from surrounding obstructions — chimneys, aerials, trees, dormer windows, and neighbouring buildings. Even partial shading on a small portion of your roof can significantly reduce system output.
Why shading has such a large impact:
- In a string inverter system, shading on one panel drags down the output of all panels in that string
- Even microinverter systems lose output from the shaded panel itself
- Tree shading changes seasonally — a tree that causes no summer shading may cast long shadows in winter when it matters most for overall annual output
Tools used in shading analysis:
- Solar Pathfinder / Solmetric SunEye: physical instruments that photograph the sky hemisphere and calculate shading losses
- PVGIS horizon tool: uses horizon elevation data from your location
- Drone surveys: increasingly used for complex roof layouts
Shading losses of 10–30% are common in suburban gardens with mature trees. If your roof has significant shading, microinverters or power optimisers (SolarEdge) can reduce — but not eliminate — the impact. In some cases, choosing a less shaded (perhaps smaller) roof section produces better financial returns than filling a larger shaded area with panels.