Irradiation models

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Irradiation models

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Irradiation on the PV-field

We call " effective incident irradiation" Heff the luminous energy actually falling on the PV cells.

It is obtained according to the following steps:

-If only monthly meteorological data available: Generation of hourly synthetic meteo data (horizontal global irradiance and temperature),

-If diffuse irradiance measured data not available: diffuse irradiance model,

-If horizon (far shadings): calculation of the beam effective component (in this version of the program, the diffuse is considered as not affected by horizon).

At this stage, we have the Horizontal global, diffuse and beam components at disposal, with the relation:    Gh = Dh + Bh.

-Computation of the so-called "incident energy" by a Transposition model, i.e. calculation of the irradiance on the PV tilted plane.

At this stage, the plane irradiance is composed of   global, diffuse, beam and albedo components, with the relation:    Gp = Dp + Bp + Ap.

-Applying the near shading calculations (shading factor on beam, diffuse and albedo components), either linear or according to electrical array connections,

-Applying the IAM (Incidence Angle Modifier factor),

this finally results in the Geff irradiance, the flux effectively useable for PV conversion. Heff  will be the corresponding irradiation over a given time period.

Note: we usually use G for designing irradiances (flux expressed in [W/m²]) and H for irradiations (energies in [kWh/m²].