How to fix legend error??

Hi

my code is running well but I have a legend error

when I write 'legend('Curve Name')' it appears only the first one

(Warning: Ignoring extra legend entries.

> In legend>set_children_and_strings (line 646)

In legend>make_legend (line 316)

In legend (line 259)

In finalstepsolar (line 68)

Warning: Ignoring extra legend entries.

> In legend>set_children_and_strings (line 646)

In legend>make_legend (line 316)

In legend (line 259)

In finalstepsolar (line 82)

>> )

any help please

K=1.38065e-23;                                           %Boltzman Constant
q=1.602e-19;                                             %Electron's Charge
Iscn=3.8;                               %Desigerable Short Circuit Current 
Vocn=21.1;                               % Desigerable Open Circuit Voltage 
Kv=-0.073;                                  % Temperature  Voltage Constant 
Ki=0.003;                                   %Temperature  Current Constant
Ns=36;                                     %Number of Series Conected Cells
Np=6;
T=25+273;                                 % Operating Temperature in Kelvin
Tn=30+273;                                              %Temperature at STC 
Gn=1000;                                                 %Irradiance at STC 

A=3.3;                                     %Diode Ideality Constant 
%%A= [Si-mono=1.2, Si- poly =1.3, a-Si:Hi=1.8,a-Si:Hitandem=3.3,a-Si:Hitriple=5, CdTe=1.5, CIS=1.5, AsGa=1.3 ]
a=(Ns*A*K*Tn)/q;
Eg=1.2;                         %Band Gap of silicon at Temperature of STC condition [ 25 deg. Cel]
G=1000;                                                  %Actual Irradiance
Rs=0.221;                          %Series Resistance of Equivalent PV cell 
Rp=415.405;                      %Parallel Resistance of Equivalent PV cell
%%%%%%%%%%%%%%% Parameter's Value Calculation  %%%%%%%%%%%%%%%%%
Tn2=80+273;
for Tni=Tn:5:Tn2
Vtn=Ns*((K*Tn)/q);                                             % Equation 2
I0n=Iscn/((exp(Vocn/(a*Vtn)))-1);                              % Equation 5

I0=I0n*((Tni/T)^3)*exp(((q*Eg/(a*K))*((1/Tni)-(1/T))));           %Equation 4
Ipvn=Iscn;
Ipv=(G/Gn)*(Ipvn+Ki*(T-Tni));                                    %Equation 3
Vt=Ns*((K*T)/q);
i=1;
I(1)=0;

for (V=Vocn: -0.1:0)
    
    I_term1=I0*(exp((V+I(i)*Rs)/(Vt*a))-1)*Np;             %Part of Equation 1
    
    I_term2= (V+I(i)*Rs)/Rp;                           % Part of Equation 1
    
    I(i+1)=Ipv-(I_term1+I_term2);                               %Equation 1
     %%%%Ipv(i)=(G/Gn)*(Ipvn+Ki*(T-Tni));
    if I(i)>0                     % Negative Power and Current Control Loop
       I(i)=I(i);
    else 
       I(i)=0;
    end
    
    
    Pi(i)=V*I(i);
    
    Vi(i)=V;
    
    i=i+1;
end

%%%%%%%%%%%% Graphical Interface   %%%%%%%%%%%%%%%%%%%
figure
hold on;
plot(Vi(1:i-1),I(1:i-1),'b', 'Linewidth',1.5)

xlabel('Voltage (volt)');
ylabel('Current (Amp)');

legend('T=30 C','T=35 C','T=40 C','T=45 C','T=50 C','T=55 C','T=60 C','T=65 C','T=70 C','T=75 C','T=80 C')


idxmax = find(Pi == max(Pi));
figure
plot(Vi(1:i-1),Pi(1:i-1), '-p','MarkerIndices',[ idxmax],...
    'MarkerFaceColor','red',...
   'MarkerSize',8)



xlabel('Voltage (volt)');
ylabel('Power (Watt)');

legend('T=30 C','T=35 C','T=40 C','T=45 C','T=50 C','T=55 C','T=60 C','T=65 C','T=70 C','T=75 C','T=80 C')
end

[Jonas]

if you plot in a loop and you want all plots to be to be in the same figure then please call figure() once before the loop and the legend() command once after the loop

[Jan]

Avoid confusing useless expressions like: I(i)=I(i); This wastes time only.w

    if I(i)>0                     % Negative Power and Current Control Loop
       I(i)=I(i);
    else 
       I(i)=0;
    end

% Nicer:
I(i) = max(0, I(i));  % [EDITED, Thanks Raymond]

[Raymond Norris]

max, not min, right?

[zina shadidi]

Thanks alot Jan and thank you Raymond. It is very nice of you to Replay

But my probem still exist.

Answer 1

[Star Strider]

Try this —

K=1.38065e-23;                                           %Boltzman Constant
q=1.602e-19;                                             %Electron's Charge
Iscn=3.8;                               %Desigerable Short Circuit Current 
Vocn=21.1;                               % Desigerable Open Circuit Voltage 
Kv=-0.073;                                  % Temperature  Voltage Constant 
Ki=0.003;                                   %Temperature  Current Constant
Ns=36;                                     %Number of Series Conected Cells
Np=6;
T=25+273;                                 % Operating Temperature in Kelvin
Tn=30+273;                                              %Temperature at STC 
Gn=1000;                                                 %Irradiance at STC 

A=3.3;                                     %Diode Ideality Constant 
%%A= [Si-mono=1.2, Si- poly =1.3, a-Si:Hi=1.8,a-Si:Hitandem=3.3,a-Si:Hitriple=5, CdTe=1.5, CIS=1.5, AsGa=1.3 ]
a=(Ns*A*K*Tn)/q;
Eg=1.2;                         %Band Gap of silicon at Temperature of STC condition [ 25 deg. Cel]
G=1000;                                                  %Actual Irradiance
Rs=0.221;                          %Series Resistance of Equivalent PV cell 
Rp=415.405;                      %Parallel Resistance of Equivalent PV cell
%%%%%%%%%%%%%%% Parameter's Value Calculation  %%%%%%%%%%%%%%%%%
Tn2=80+273;

Dname1 = {'T=30 C','T=35 C','T=40 C','T=45 C','T=50 C','T=55 C','T=60 C','T=65 C','T=70 C','T=75 C','T=80 C'};

figure
hold on
k1 = 0;
for Tni=Tn:5:Tn2
    k1 = k1+1;
Vtn=Ns*((K*Tn)/q);                                             % Equation 2
I0n=Iscn/((exp(Vocn/(a*Vtn)))-1);                              % Equation 5

I0=I0n*((Tni/T)^3)*exp(((q*Eg/(a*K))*((1/Tni)-(1/T))));           %Equation 4
Ipvn=Iscn;
Ipv=(G/Gn)*(Ipvn+Ki*(T-Tni));                                    %Equation 3
Vt=Ns*((K*T)/q);
i=1;
I(1)=0;


for (V=Vocn: -0.1:0)
    
    I_term1=I0*(exp((V+I(i)*Rs)/(Vt*a))-1)*Np;             %Part of Equation 1
    
    I_term2= (V+I(i)*Rs)/Rp;                           % Part of Equation 1
    
    I(i+1)=Ipv-(I_term1+I_term2);                               %Equation 1
     %%%%Ipv(i)=(G/Gn)*(Ipvn+Ki*(T-Tni));
    if I(i)>0                     % Negative Power and Current Control Loop
       I(i)=I(i);
    else 
       I(i)=0;
    end
    
    
    Pi(i)=V*I(i);
    
    Vi(i)=V;
    
    i=i+1;
end

%%%%%%%%%%%% Graphical Interface   %%%%%%%%%%%%%%%%%%%
% figure

subplot(2,2,1)
hold on
plot(Vi(1:i-1),I(1:i-1),'b', 'Linewidth',1.5, 'DisplayName',Dname1{k1})

xlabel('Voltage (volt)');
ylabel('Current (Amp)');

% legend('T=30 C','T=35 C','T=40 C','T=45 C','T=50 C','T=55 C','T=60 C','T=65 C','T=70 C','T=75 C','T=80 C')


idxmax = find(Pi == max(Pi));
% figure
subplot(2,2,2)
hold on
plot(Vi(1:i-1),Pi(1:i-1), '-p','MarkerIndices',[ idxmax],...
    'MarkerFaceColor','red',...
   'MarkerSize',8, 'DisplayName',Dname1{k1})



xlabel('Voltage (volt)');
ylabel('Power (Watt)');
hl = legend;
end
hold off
subplot(2,2,[3 4])
Ax = gca;
Ax.Visible = 'off';
pos = Ax.Position

pos = 1×4

0.1300 0.1100 0.7750 0.3412

hl.NumColumns = 3;
hl.Position = pos;

I added the ‘k1’ counter and changed the order of the figure and hold calls, and changed the legend call to include 'DisplayName' strings.

This should get you closer to the result you want.

[zina shadidi]

thank you Star Strider , its working and I like the new figure.

[Star Strider]

As always, my pleasure!

Thank you!