Shading is one of the main sources of energy losses and uncertainty in photovoltaic systems. In many real installations, shading effects are driven by complex geometries that cannot be represented accurately using simplified or two dimensional assumptions.
Such situations include irregular terrain, nearby infrastructure, non standard support structures, vegetation, moving elements, or combinations of multiple shading sources. In these cases, the spatial and temporal distribution of shading can strongly influence irradiance, electrical performance, and loss mechanisms.
LuSim has been developed to address these situations explicitly through a 3D modelling approach that represents shading as a direct consequence of geometry and solar position.
LuSim represents photovoltaic systems and their surroundings directly in three dimensions. Terrain, PV structures, buildings, vegetation, and other objects are modelled as explicit geometric entities rather than simplified masks or horizon profiles.
This representation allows shading interactions to be evaluated based on actual geometry. Shading sources can be static or dynamic, and their interaction with the PV system evolves naturally over time as the sun position changes.
By working directly in 3D space, LuSim captures effects such as partial shading, self shading, and asymmetric shading patterns that are often missed by simplified approaches.
Shading does not affect all parts of a photovoltaic system uniformly. Localised shading can lead to non-uniform irradiance distributions across modules or module regions, which in turn influence electrical behaviour and losses.
LuSim evaluates shading and irradiance at a high spatial resolution. View factors and visibility are computed locally in three dimensions for discretised surface elements, rather than using aggregated or two dimensional approximations.
This makes it possible to identify where shading occurs, how extensive it is, and which parts of the system are most affected. Such spatially resolved information is particularly relevant for understanding mismatch effects, identifying critical areas, and comparing alternative design options.
Direct irradiance is governed by line of sight between the sun and each point of the photovoltaic system. Shading of the direct component is therefore a geometric visibility problem, where a surface element is either directly illuminated or obstructed by another object at a given time.
LuSim evaluates shading of the direct component using a rasterization based approach on the GPU. For each solar position, the 3D scene is rendered from the sun’s point of view. This process determines which discretised surface elements are visible from the sun and which are shadowed due to geometric occlusion.
Rasterization is well suited to this task because it efficiently handles complex scenes with many objects while preserving high spatial resolution. It allows partial shading, self shading, and fine geometric details to be captured consistently across the system.
This approach enables the dynamic evaluation of direct shading throughout the year, following the continuous evolution of solar position.
Diffuse and reflected irradiance originate from extended sources rather than a single direction. The sky, the ground, and surrounding surfaces contribute radiation from a wide range of directions simultaneously.
For these components, shading cannot be represented as a binary visibility problem. Instead, it depends on how much of each radiative source is visible from each surface element.
LuSim addresses this using a high spatial resolution 3D view factor formulation. View factors are computed locally between discretised surface elements in three dimensions, taking into account their relative orientation, distance, and mutual visibility.
This approach goes beyond simplified two dimensional or aggregated view factor models. Partial occlusion of the sky dome, the ground, or surrounding objects directly reduces the effective view factors toward these sources rather than switching irradiance on or off.
As a result, diffuse and reflected irradiance are evaluated consistently in complex environments, including situations with heterogeneous surroundings, vertical structures, and partial enclosures.
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