Different outputs for the same inputs for model predictive controller in Microgrid using scripts

I have a microgrid connected to a model predictive controller, and I created a custom cost function using scripts. Although the model is linear, I used nonlinear MPC because I needed a custom cost function. However, when I run the model many times, I get different plots for the same inputs. What could be causing this?

I will show you differents results for the same inputs;

ps: I choose the Euler method for state calculating fct;