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A concentrating system is defined when involving a concentrating PV module (CPV).

Defining a CPV module in PVsyst is done in the PV module definitions, part "Size and Technology".

Only high concentrating CPV devices (with a concentrating factor of the order of 500x) are possible in PVsyst. These are usually equipped with very high efficiency concentrating cells (triple junction GaInP2/GaAs/Ge). The optical characteristics and real electrical behavior of the cell cannot be modeled in detail. Therefore, as an approximation, the full CPV module is treated as if it was a flat PV module, with a sensitive area equivalent to the optical aperture area.

The thermal behavior - with heat sinks for evacuating the heat of the cell - is supposed to behave in the same way as the flat plate modules, i.e., according to the usual thermal balance equation with a heat loss factor U as parameter.  Now there is no general rule for the determination of this thermal factor, which depends on the heat sink properties. Therefore, this should be specified by the module manufacturer.  

The CPV module is only able to use the beam component. A concentrating factor of 500x means an ideal acceptance angle of 2.5° at most (less than 1° in the reality) so that the diffuse contribution is completely negligible. This is the reason why the industry of CPV modules has fixed the STC irradiance value at 850 W/m² instead of 1000 W/m² for usual modules (but still with a cell temperature of 25°C).  

When specifying a CPV module in PVsyst, you have the opportunity of defining specific corrections, namely for the spectral behavior. This correction is named the CPV Utilization Factor.

For applying this correction, you can define - in the PV module model parameters - a double-linear behavior according to:

- the Beam normal value (DNI),

- the air mass (the CPV module will always operate in clear day conditions),

- the ambient temperature (not for spectral response, but for accounting of optic's mechanical deformations).

Again, these corrections are determined from long-term measurement in real conditions, and should be given by the manufacturers.