problem to solar maximum power for resistive load

first figure showed power is 315.1w which is maximum power for this solar panel.

when I changed irradiance from 1000 to 500, figure as blow

How come the power is only 87.59w (load keeps unchanged)?

How can I always find maximum point power as load is fixed but irradiance or temperature varys?

thanks.

Answer 1

[Salah]

You have a constant load in the figure, and you are calculating the power P = IV, so changing the irradiance will always change the output current from the cell thus the voltage, which will vary the power calculated and the load will still be constant.

[Kian]

thanks in advance. then How do we make solar panel always track the mpp when irreadiance or temperature changes no matter if the load changes?

[Salah]

You need a system with a feedback and a controller, a controller algorithm can be something like this: MPPT Algorithm - MATLAB & Simulink (mathworks.com)