Issue calculating same PV curve as Simulink PV block outputs

I am trying to replicate the _1Soltech 1STH-215-P IV and PV curves programmatically but I keep overshooting as you can see in the image below (my lines are thin red in the IV plot, thin blue in the PV plot). I used the formulas from Power Electronics for Photovoltaic Power Systems textbook (screenshot below).

In short, first I go to the PV block in simulink (screenshot below) and plot curves @25C for 800 and 1000 W. Then I call my 'PVCurveGenerator' function after 'hold on'. I want to be able to generate my own curves for any irradiance and temperature.

function [Vmpp, Pmpp, Impp] = PVCurveGenerator(G, T, plotyn)

    %%MATLAB PV array parameters

    % Fill in panel specifics for diode model. Grouping them like the MATLAB
    % PV Array block does

    nser = 60; % Number of cells in series in a module
    npar = 1; % Number of cells in parallel
    Vnom = 36.3;  % Open circuit voltage under nominal conditions (V)
    Inom = 7.84;  % Short circuit current under nominal conditions (A)
    Vmp = 29;  % Maximum power voltage (V) - must be for nominal conditions
    Imp = 7.35; % Maximum power current (A) - must be for nominal conditions
    KVoc = -0.36099;  % Temperature coefficient of Voc (%/deg. C)
    KIsc = 0.102;  % Temperature coefficient of Isc (%/deg. C)

    I0 = 2.9273e-10;  % Diode saturation current (A)
    p = 0.98117;  % Diode ideality factor
    Rsh = 313.3991;  % Shunt resistance (Ohms)
    Rs = 0.39383;  % Series resistance (Ohms)

    Gnom = 1000;  % Nominal irradiation (W/m^2)
    Tnom = 298.15;  % Nominal temperature (K)
    q = 1.60217662e-19;  % Charge constant
    k = 1.38064852e-23;  % Boltzmann's constant

    %%Plotting I-V curve

    Isc = (Inom + KIsc*(T-Tnom)).*(G/Gnom);  % Isc under input conditions
    Voc = (p*k*T*nser/q).*log(Isc/I0 + 1);  % Voc under input conditions

    Vd = 0:0.05:Voc;
    Vt = (k.*T/q)*p*nser;
    I = npar*(Isc - I0 * (exp(Vd./Vt) - 1))*Rsh/(Rsh + Rs) - Vd/(Rs + Rsh);
    P = I.*Vd;
    Pmpp = max(P);
    Impp = max(I);
    Vmpp = Vd(P == Pmpp);

    if(plotyn)
        fprintf('Isc: %.2f\n', Isc);
        fprintf('Voc: %.2f\n', Voc);

    %         figure(2);
        subplot(2,1,1)
        plot(Vd, I, 'r');
        xlabel('Voltage [V]');
        ylabel('Current [A]');
        title('PV Array I-V curve');
        ylim([0 1.05*Isc]);

        subplot(2,1,2)
        plot(Vd, P, 'b');
        xlabel('Voltage [V]');
        ylabel('Power [W]');
        title('PV Array P-V curve');
        ylim([0, 1.05*max(P)]);
    end
end

Answer 1

[Harish Ramachandran]

I am unable to access the textbook. One possible reason for the graph overshoot could be due to a difference in the coefficients.

Please refer to the : https://www.mathworks.com/help/physmod/sps/powersys/ref/pvarray.html