BuildSysPro.Systems.Solar.PV.BaseClasses.Optics.PVTransmissionFactors

# .BuildSysPro.Systems.Solar.PV.BaseClasses.Optics.PVTransmissionFactors

Calculation of direct, diffuse and albedo transmission factors of incident rays on a photovoltaic module

## Information

Hypothesis and equations

This model allows the use of analytical formulas for evaluating optical losses due to reflection on the three components of the solar flux : direct, diffuse and reflected by the ground (albedo).

This model is a improvement of the model developed by ASHRAE which is not valid for angles of incidence higher than 80°.

- The expression of the transmittance factor for the direct incidence is given by :

: sun rays angle of incidence on the module.

: module relative transmittance due to its degree of dirt.

: coefficient characterizing the dirt of the module ( values are related to the values of the relative transmittance).

Note : The formula used is not exactly the one that can be found in the literature, the multiplicative factor of relative transmittance can be included in the transmission factor as shown in equation (20.49) of the "Handbook of Photovoltaic Science and Engineering", P936.

- For diffuse radiation, the expression is :

- And for albedo radiation, the expression is :

: constant coefficient.

: coefficient linearly dependent of dirt coefficient (automatically calculated in the model).

: module tilt angle.

Instructions for use

none

Bibliography

Handbook of Photovoltaic Science and Engineering, Antonio Luque & Steven Hegedus, Wiley, 2003, pp. 934-936

Martin N., Ruiz J, Solar Energy Materials & Solar Cells 70, 25-38, 2001

Known limits / Use precautions

The values of the dirt parameter a_r have not been studied, validations have been made only considering a clean module.

Validations

Model validated by simulation - Sergeï Agapoff (stagiaire Benoît Braisaz) 08/2012

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Licensed by EDF under a 3-clause BSD-license
Copyright © EDF 2009 - 2023
BuildSysPro version 3.6.0
Author : Sergeï AGAPOFF, EDF (2012)
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## Revisions

Agapoff Sergeï 04/2012 : Model creation

Stéphanie Froidurot 07/2019 : Adding the possibility to use fixed (parameter) or prescribed (input) tilt and azimut, controlled by booleans (use_incl_in and use_azimut_in).

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