Array Sizing

[tolga]

Hello,

I have a trouble about sizin array. There is a difference in operating conditions between calculated by PVsyst and me.

For example, I calculate operating conditions;

Voc(-10) = Voc,stc * (1 + (Toc-Tstc)*b);

b is Temperature Coefficients of V, for selected panel b is -0.31 %/C so;

Voc(-10) = 37.7 * (1 + (-10-25)*-0.31%) = 41.79 V

likewise Vmpp (60C) = 27.10 V.

Calculated operating conditions;

Voc(-10C) = 835.8 V

Vmpp(60C) = 542 V

There is a dramatic difference, especially for higher temperatures. I can't figure out what is reason.

System Design by PVsyst

Edited December 1, 2015 by tolga

[André Mermoud]

The Voc is computed according to the one-diode model. However the temperature coefficient is not quite linear with the temperature.

On the other hand, the values of the one-diode model are not necessarily conpliant with the value specified in the datasheets.

Please see our FAQ How to adjust the Voc temperature coefficient ?.