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Shadings

We distinguish between two fundamentally different types of shadings:

  • Far shadings are described by a horizon line. These concern shadings from objects sufficiently distant that they affect the PV field globally: at any given time, the sun is either visible or not visible on the field. Typically, these shading objects should be at a distance greater than approximately ten times the PV field size.
  • Near shadings are shadings produced by nearby objects that cast visible shadows on the PV field. The Shading Factor is defined as the ratio of the shaded area to the total sensitive area of the field. Treatment of near shadings is much more complex than far shadings and requires a detailed 3D description of the complete PV system and its surroundings.

This is the most difficult part of the PVsyst software. For beginners, you have a tutorial that explains the main procedures with an example.

During the simulation, shading calculations must be computed at each time step and applied differently to the beam, diffuse, and albedo components (see Shadings Calculation and Model).

For the beam component of near shadings, two types of losses must be considered:

  • Irradiance losses correspond to the irradiance deficit on the cells (formerly called "Linear shading losses"),
  • Electrical losses result from mismatch in the electrical response of series modules and parallel strings: for example, in a module string (or cells), the total current is always determined by the current in the weakest cell.

PVsyst provides 2 different ways to treat these electrical losses:

Note that a model equivalent to the "according to strings" mode for accounting electrical losses may also be used with the "unlimited" orientations. These orientations provide an alternative way to include mutual shadings in the simulation.

See "Near shadings, main dialog" for the general procedure, and the different ways of performing shading calculations.