Why are the range of values for the waveforms on the scope on my model far above the specifications that I used for my simulation?

I am doing a simulation of MPPT using Simulink. The waveforms I get from the simulation look good except that the values on the scopes are not within the range I used for the PV module model. For example the maximum power for 1000 Watts/square meters irradiance should be 87W but I get around 600 W on the scope. Could anyone help me resolve this problem please? Thanks.