PV module: define low-light data

This dialog allows to define performances of your module at different (G, T) conditions.

Usually (for Rserie determination) the Relative efficiencies at 800, 600, 400 and 200 W/m² and 25°C, with respect to the STC efficiency.

On the top right of the panel, you have different options:

Define points

Simple definition

You simply define some operating points with Irradiance, Temperature, Relative efficiency.
These data may have been defined explicitely by the manufacturer in the database.

Complete definition

When checking "Rel. efficiency from STC", you can enter the full measured data (Isc, Voc, Imp, Vmp) at different conditions, and the program will calculate the relative efficiencies with respect to the STC of the module.

Efficiencies

Displays a plot showing the points you have defined and the model with current parameters. The "Rel efficiencies" shown on the plot are the model results at 800, 600, 400, and 200 W/m².

Effic errors

Shows the differences between your operating points and the model (different colors for different temperatures). You can now modify the Rserie and Rshunt values and optimize Rserie to see the effects compared to your specified points.

ISC check

If you have performed a complete definition with (Isc, Voc, Imp, Vmp), this option allows a quality check of the measured data.

According to most models, ISC values should be perfectly proportional to irradiance.

If the Isc/G values are not identical for each measured point, this indicates an error in the irradiance measurement (for example, in the calibration of the filters used for the flash test).

In this case, you have a Linearize Isc/G button, which will slightly modify the "measured" G values to perfectly linearize this ratio. The relative efficiencies (normalized to these corrected G values) should be more accurate, as they do not include a G measurement uncertainty.

Conversely, the button becomes Retrieve Gref to return to the original data.

Again, the o Efficiencies and o Effic errors options allow you to adjust the Rshunt and Rserie with direct visualization of the effect.