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Shading models calculate irradiance reduction from geometric obstructions between the (sun included) and the PV modules. This section covers:
  • Horizon Shading — far-field obstructions (terrain, buildings)
  • Sky Diffuse Shading reduction of sky diffuse irradiance from nearby rows
  • Ground-Reflected Shading reduction of ground-reflected irradiance with IAM effects
  • Direct Beam Shading — near-field row-to-row and structural shading
  • Electrical Effect of Shading — conversion of geometric shade to electrical loss

Models in This Section

Horizon Shading

Far-field shading from terrain features and distant obstructions. Applied to the beam component before near-field geometric shading.

Sky Diffuse Shading

Sky view factor reduction from adjacent rows blocking part of the sky hemisphere. This calculation is purely geometric—IAM effects on sky diffuse irradiance are handled separately in the IAM model.

Ground-Reflected Shading

Ground view factor reduction accounting for both sunlit and shaded ground between rows. Unlike sky diffuse shading, this calculation includes IAM effects using the ASHRAE model, since ground reflection arrives at oblique angles.

Direct Beam Shading

Near-field shading from row-to-row and structural obstructions:
  • Row-to-Row Beam Shading - DC Field Level: Analytical model for standard row-to-row shading on flat or uniformly sloped terrain
  • 3D Shading - DC Field Level (Legacy): Shadow volume projection for complex DC field geometry, limited to single DC field scope
  • 3D Shading - Site Level (Version 12+): Polygon clipping algorithm for full site-level 3D shading (automatically enabled with 3D scene)

Electrical Effect of Shading

Converts geometric shade fraction to electrical power loss:
  • None: No shade loss applied
  • Linear: Shade loss equals geometric shade fraction (no additional electrical effect)
  • Fractional: A user-defined fraction of the module (e.g., 20%, 50%, 100%) is lost when any shade is present; geometric shade applies to the remaining portion
  • Step-Fractional (Version 12+): Total loss increases in discrete steps as shade crosses partition thresholds (e.g., 0%, 50%, 100% for 2 partitions)