Does PVsyst treat concentrating systems ?

[André Mermoud]

PVsyst is not suited for the study of any concentrating PV systems. Only the high concentration systems (CPV) are treated under some conditions (see below).

Modelling concentration with sufficient accuracy and generality is a very difficult task, which requires probably a research project by itself.

- The irradiance acceptance is strongly dependent on the real mirrors geometry and quality, and also on the exact irradiance angular distribution, which is usually not available in the PVsyst meteo models (should include variables like turbidity, humidity, etc).

- The PV module or cells performances are strongly related to the irradiance distribution and its homogeneity.

- It involves an accurate description of the mechanical structure and its control (a little tracking error may have drastic consequences),

- The results are closely related to the beam part of the meteo, which should be known with precision. This is not the case with the usually available meteo data and models.

Example: several months after the Pinatubo eruption, the high concentrating power plants in USA observed losses of 30% while the global irradiance only dropped by 2% !

Therefore concentrating is not foreseen in PVsyst at the moment in whole generality.

Only the high concentration (500x) has been developed up to now (in collaboration with one specific user), as it doesn't involve special effects on the diffuse, simply it withdraws it. But this involves a doubtful model for the PV module, which is assumed as a "flat" module of the size of the mirror's aperture. The PVsyst model for cells has not been extended to high irradiances of 500 suns, and the optical effects in the module's parabolic mirrors is too specific to each product for being modelled in generality here.

Several adjustments of the one-diode model have been stated by experiments and are available in the present version (derates according to DNI, air mass and ambient temperature).

Without a close cooperation with the manufacturer, it is probably not possible to establish the parameters of this approximated model for the module.