PVfunction.m

% Photovolatic function  that is used to plot the power to voltage using
% irradiance value and the temperature value 
function [P,Pmax,Vmax] = PVfunction(T,G)
ai=0.034/100;                     % Current Tmperature coefficient(ki)
av=-0.34/100;                     % Voltage Tmperature coefficient(kv)
Isc_r=3.99;                        % Short-circuit current
Voc_r=22.1;                       % Opent circuit voltage
Vm=17.6;                            % Maximum voltage @ STC
Im=3.69;                          % Maximum current @ STC
Pm=65;                           % Maximum power   @ STC
Ns=36;                            % nomber of Cells   
n=0.9;                            % Diode ideality factor

%% Internal parameters%%%%%%%%%%%%%
Gr=1000;                          % reference irradiance
    T=T+273.6;                        % 
    Tr= 25 +273.6;                    % Temperature reference
    dT=T-Tr;
    Isc=Isc_r+ai*dT;                  % variation of Isc with T°
    Voc=Voc_r+av*dT;                  % variation de Vco with T°
    q=1.60217646*power(10,-19);       % charge constant
    K=1.3806503*power(10,-23);        % Boltzmann constant
    Vt=(Ns*n*K*T/q);                  % Thermal voltage 
    Eg=1.12;                          % gap energy
    Iph=Isc*(G/Gr);                   % photo-current
    Iss=(Isc)/(   exp( Voc/Vt )-1 );  % saturation current
    Is=Iss*( (T/Tr)^3 ) * exp ( ( (q*Eg)/(n*K) )*((1/Tr)-(1/T)) );%saturation current
    Rs=0.5;                           % series resistance 
    Rp=195;                           % parallele resistance
%%
I=Iph;             % initial codition
V=0:(Voc/100):Voc; % input voltage array
for n1=1:length(V) 
    
        
    for n2=1:20                          % Newton-Raphson loop for calculating output current
    Vd= (V(n1)+Rs*I);                    % Diode Voltage
    Id=Is*( exp(Vd/Vt) -1);              % Diode current
    Ip=Vd/Rp;                            % Parallele resistance Current
    f=Iph-I-Id-Ip;                       % f(I)=0
    df=-1-(Is*Rs/Vt)*exp(Vd/Vt)-(Rs/Rp); % f'(I)=0
    I=I-f/df;% Newton-Raphson formula
    
    end % end of Newton-Raphson
    
    if I<0
        I=0;
    end
    Ipv(n1)=I;  
    % Accumulation of output currant

end 
%%
 P=Ipv.*V;% Output power

 [Pmax,ii] = max(P); Vmax = V(ii);
% Plot the P-V graph 
% figure(1)
% hold on
% plot(V,Ipv)%  
% grid on
figure(2)
title("P-V curve")
plot(V,P)
hold on
grid on
end