Questions regarding PV system model in Simulink

Hi, I have a question regarding simulink PV system model. I have downloaded the 250 kW grid connected PV model from mathworks website and tried to modify to get 5 MW out of it. I have changed the number of parallel strings as I don't want to change the existing voltage level on both sides of the inverter. I was looking for changing other parameters in that model but found almost all of the things are given in the form of formula which deterred me from changing them. To make the system compatible for absorbing 5 MW power I have converted the 250 kW load to 5 MW constant Z load. But I am getting really weird result (instead of feeding to the grid, I am getting backfeed from the grid), can anyone give me any suggestion or solution regarding that. My email ID is: [e-mail]