When I provide Vpv = 0:0.1:30 the desired 'x' value is not changing,i'm getting an array of a single value... but , if I give a single value of Vpv, i get corresponding 'x' value. Where is the modification needed for getting variable 'x' values?

Function file :

function F = pvcurve( Ipv ) 
global Np Ns Isc q T k Io n 
Vpv= 100 ; 
% Np = 1 ; 
% Ns=72 ; 
% Isc =1.82 ; 
% q= 1.6e-19 ; 
% T=298 ; 
% k=1.38e-23 ; 
% Io= 1.2987e-4 ; 
% n=1.8405 ;
 for i=1:length(Vpv)  
F(i) = -(Ipv)+ (Np*Isc)- Np*Io*((exp((q*Vpv(i))/(n*k*T*Ns))-1));
 end
end

Main file :

clear;clc;close all;
Vpv= 100 ; 
Ipv0 = 0; 
global Np Ns Isc q T k Io n 
Np = 1 ; 
Ns=72 ; 
Isc =1.82 ; 
q= 1.6e-19 ; 
T=298 ;  
k=1.38e-23 ; 
Io= 1.2987e-4 ; 
n=1.8405 ; 
for i=1:length(Vpv)
x(i) = fsolve(@pvcurve, Ipv0 )
end

Answer 1

[Walter Roberson]

>> syms Np Ns Isc q T k Io n Vpv Ipv
>> F = -(Ipv)+ (Np*Isc)- Np*Io*((exp((q*Vpv)/(n*k*T*Ns))-1));
>> solve(F,Ipv)
ans =
Isc*Np - Io*Np*(exp((Vpv*q)/(Ns*T*k*n)) - 1)

So, you do not need fsolve: you can just code your constants and your vector of values for Vpv, and then

x = Isc*Np - Io*Np*(exp((Vpv*q)/(Ns*T*k*n)) - 1);

all solved at one time.