How Isc and Voc influence all the other single-diode parameters in the mismatch tool?

[gcata]

Hello,

In the "Graphical tool for determining the effect of parameter mismatch" the 2 independent parameters are: Isc and Voc.

If a pair of Isc and Voc is enough to create IV curves, it means all the other single-diode parameters are dependent or kept constant to the avg. module characteristics.

How are the other parameters calculated? Which are free and which are constant?

My guess is that:

- Constant to the module .pan values:

gamma_ref, alpha_isc (isc temp coefficient), mu_gamma, rsh_ref, rsh_0 and rsh_exp.

- Pmpp is dependent to Isc and Voc through the fill factor FF.

- I_ph, I_0 and rs_ref are the other dependent parameters: calculated with the equations of the single-diode system by

making the IV curve pass by Pmpp, Isc and Voc from above.

Is it right? or do you keep other parameters constant?

Thank you very much for your support,

Gabriele

[André Mermoud]

In fact in this tool, we don't need the full one-diode model as the addition of I/V curves is only done at STC values.

Therefore PVsyst simply performs a scaling of the I/V curve in voltage and current, with respect to the original model.

This is an approximation, however probably largely sufficient for such an "uncertain" random calculation.