For each point of near objects (p0) the shadow cast (pS) on the plane of the PV modules (p1-p2-p3) is calculated.
The shadow polygon is clipped to the module surface
Source of graphic: Quaschning: “Simulation der Abschattungsverluste bei solarelektrischen Systemen” pdf
The ratio of shadow size to module area gives the degree of shadowing. In PV*SOL® the x-y shadowing vectors are calculated at string or cell level to ensure highest simulation accuracy.
In the shaded module area, only the diffuse radiation reaches the PV cells. In the unshaded area, full global radiation reaches the cells.