PV modules - Additional data

This page contains additional optional data specified for this module, and tools for the elaboration of the model.

Low-light data

Some unknown parameters of the model, especially the Series Resistance, have a great impact on the Low-light behavior of the model. Therefore the low-light efficiency measurements are a powerful mean for a good determination of these parameters.

With this tool, you can enter:

either relative efficiencies with respect to the STC efficiency. Acceptable values usually don't exceed +0.5% to +1% for 800 W/m² and 600 W/m², and may be of the order of -3% or less at 200 W/m² (crystalline modules)..
or directly the measured Imp, Vmp, Isc, Voc values at different irradiances, from which the relative efficiencies will be calculated.

After these definitions for at least 4 irradiance levels (800, 600, 400, 200 W/m²), you can ask for optimizing the Rserie of the model.

Measured I/V curve

This tool allows to import a Measured I/V curve (for example from msEXCEL), and then adjusts the Rshunt and Rserie for matching this curve.

Sandia Model parameters

When a corresponding module is available in the Sandia database, this page shows all the Sandia parameters, and the differences with the PVsyst parameters for this module.

This gives the spectral correction applied by the Sandia model (as a function of the Air Mass), and compares the IAM curves of both models (which are significantly different, but for angles where the energy is not very important).

NB: for a comparison of the model results, please press the button Sandia-Diode compare.

In this page you can eventually choose another module in the Sandia database,

Customized IAM

An IAM profile can be associated to the PV module. This may be defined either by a "bo" parameter for the ASHRAE parametrization, or by a customized profile.

This definition can then be used in the simulation: you have to define this in the "Detailed losses" parameters.

Secondary parameters


*Reverse characteristics*	these parameters describe the module behavior when reverse-biased (i.e. when applying a negative voltage to the module). The module may encounter reverse voltages when included in an array with partial shadings or mismatch. However the exact behavior is mainly determined by the by-pass diodes. The intermediate states when the reverse current is not sufficient for activating the diode are scarce and don't have a significant influence on the characteristics of the full shaded array. Therefore these parameters are not crucial.
Quadratic factor Brev	According to our measurements, the reverse characteristics of one single cell may be modeled by a simple quadratic function. However this reverse current is extremely depending on the cell's temperature, so that an accurate model is not really useful and applicable. Indeed in shaded conditions the cell temperature may be highly varying, depending on the cell's consumption (hot spot). You are advised to let PVsyst fix the default value of this parameter.
*Nb of by-pass diodes*	is important for the definition of the sub-modules in the ModuleLayout part and the electrical shading loss calculations.
Diode direct voltage	is used in the array I/V characteristics during shadings, but not involved in the Pmpp evaluation (only acts on low-voltage part of the curve). Therefore not relevant.
Diode Maximum current	Rarely defined by manufacturers. Never used.