MATLAB: 5 equations with 5 unknowns

Question

this is the code, and it says: Undefined function or variable 'Rp'.

Vmp=0.57
Voc=0.66
Isc=0.0067
Imp=0.0062
k=1.38e-23
q=1.6e-19
T=300
[I0,IL,n,Rs,Rp]=solve(Rp==Voc/(IL-I0*(exp(q/(n*k*T)*Voc)-1)),Isc==IL-I0*(exp(q/(n*k*T)*Rs*Isc)-1) ...
    -Rs*Isc/Rp, Imp==IL-I0*(exp(q/(n*k*T)*(Vmp+Imp*Rs))-1)-(Vmp+Imp*Rs)/Rp, Rs0==-(q/(n*k*T)*I0*exp(q/(n*k*T)*Voc) ...
    +1/Rs)/(1+Rs(q/(n*k*T)*I0*exp(q/(n*k*T)*Voc)+1/Rs)), Rp0==-(q/(n*k*T)*I0*exp(q/(n*k*T)*Rs*Isc)+1/Rs)/(1+ ...
    Rs(q/(n*k*T)*I0*exp(q/(n*k*T)*Rs*Isc)+1/Rs)));
    

please help.

thanks

Answer 1

Run this and check if the equations are those that should be...

clearvars 
syms  Vmp  Voc  Isc  mp  k  q  T Rp0 Rs0 Imp
syms I0 IL n Rs Rp 
eq1 =  Rp==Voc/(IL-I0*(exp(q/(n*k*T)*Voc)-1)) 
eq2 =  Isc==IL-I0*(exp(q/(n*k*T)*Rs*Isc)-1)-Rs*Isc/Rp
eq3 =  Imp==IL-I0*(exp(q/(n*k*T)*(Vmp+Imp*Rs))-1)-(Vmp+Imp*Rs)/Rp
eq4 =  Rs0==-(q/(n*k*T)*I0*exp(q/(n*k*T)*Voc)+1/Rs)/(1+Rs*(q/(n*k*T)*I0*exp(q/(n*k*T)*Voc)+1/Rs))
eq5 =  Rp0==-(q/(n*k*T)*I0*exp(q/(n*k*T)*Rs*Isc)+1/Rs)/(1+Rs*(q/(n*k*T)*I0*exp(q/(n*k*T)*Rs*Isc)+1/Rs))
Vmp=0.57
Voc=0.66
Isc=0.0067  
Imp=0.0062
k=1.38e-23
q=1.6e-19
T=300
Rp0=-0.0032
Rs0=-0.1535
eq1=subs(eq1); eq2=subs(eq2); eq3=subs(eq3); eq4=subs(eq4); eq5=subs(eq5);
[I0,IL,n,Rs,Rp]=vpasolve( [eq1, eq2, eq3, eq4, eq5], [I0,IL,n,Rs,Rp])

I replaced solve by vpasolve and a I filled in two multiplication signs on equations 4 and 5

You will get these results: