How to generate a P-V curve when changing the Open Circuit Voltage and Short Circuit Current Values in a Solar Cell module?

Hello,

I'm realatively new to simulink and I am trying to generate a P-V curve using a solar cell module and a variable resistor. Whenever I use the default values for Voc and Isc in the solar cell module, I get a P-V curve. However, when I change the Voc and Isc values in the solar cell, my plot shows a linear relationship instead of a curve. Is there a way to change the Voc and Isc values in the solar cell to have it display a correct P-V curve? I have provided my working Simulink model below. Thank you.