Advanced Tuning with Effective Irradiance Response

After the initial 1-diode parameters are generated, a user with knowledge of module electrical characteristics might want to optimize the module to perform with a specific effective irradiance response (EIR). A module’s EIR defines its relative efficiency at any set of irradiances (where relative efficiency is 100% at 1000 W/m2).

First click “Show Advanced Tuning Options” to expose the 1-diode Parameters and EIR tool.



Click “Add Curve” to begin specifying the desired EIR. Enter in the temperature at which the EIR will be defined, and then enter in any number of irradiances and their respective relative efficiencies (in percent). **Important Note: The current version of this feature will only use an EIR curve at 25⁰C when the user clicks “Optimize to Match EIR” under “Series Resistance at STC”. This tool is described in more detail below.

A plot will appear next to the EIR table with small circles representing the desired relative efficiencies at each irradiance, and the solid line showing the model-calculated EIR based on the currently entered electrical characteristics and 1-diode parameters.



Click the button “Difference/Error” to toggle to a plot that shows the difference between the desired and model-calculated relative efficiencies at each specified irradiance.



These two plots serve as a visual reference for optimizing the module file to perform according to a desired EIR, and will update as parameters are modified. The easiest first step towards optimizing the module is to click “Optimize to match EIR” which will algorithmically tune the “Series Resistance STC”, recalculate any 1-diode parameters dependent on Series Resistance, and result in a model-calculated EIR that is closer to the desired performance. The solid line representing model-calculated is replotted in the EIR plot to reflect this change.



However, the series resistance optimization tool does not guarantee a model-calculated EIR that is satisfactory to the user’s desired performance. It is recommended that users experienced with module performance use the “Optimize to match EIR” tool in conjunction with manual modification of the 1-diode parameters to achieve a better optimized result.

If the user wishes to revert all parameters back to those initially generated by the default algorithm, re-click the “Use algorithmic defaults” checkbox. (It automatically un-checks when the user manually modifies any of the 1-diode parameters.)