dear researchers, in many MPPT literature we find the linear relation between ipv_optimal and iph_current (ipv_opt = 0.909iph), so could you please help me to understand how they extracted this equation
Perhaps it helps to read the following paper: MODEL REFERENCE ADAPTIVE CONTROL FOR MAXIMUM POWER POINT TRACKING IN PV SYSTEMS
Dear Noureddine Boubekri ,
welcome!
The I-V relation follows the realtion
I= Iph - Is exp V/nVt
neglecting Rs.
Then P= IV= V (Iph - Is exp V/nVt)
You can also take n=1
One can get the point of the maximum power
dp/dv=0
Iph- Is exp Vm/nVt- (Vm/Vt) Is exp Vm/Vt=0
Iph= (1+ Vm/Vt) Is exp Vm/Vt , Vm is the maximum power voltage.
Iph= (1+ Vm/Vt) (Iph- Im)=(1+ log (Iph-I)/Is) (Iph- Im),
giving Is one can get Im as a function of Iph,
Only you need to search forIs for standard solar cells
better to take the currents per unit area to get correct answer.
So the rule is for standard silicon solar cells.
complete the proof and return to me!
Best wishes
Dear @Abdelhalim Zekry, in the last equation I get : Iph=(1+log(Iph-Im+1))(Iph-Im) .(I put Is=1), because Vm=nVt.log((Iph-Im+Is)/Is) after, I don't understand the final step to get the relation between Im and Iph?
Thank u
Dear @Boubekri,
welcome,
I wonder how you took Is= 1, this really far from the real value of the solar cells.
I measured the Is=1.2x10^-7 A for 4 cm^2 area of the cell.
Then Js= 0.3x10^-7 A.cm^2.
For such values please refer to the paper in the link:https://www.researchgate.net/publication/3062547_A_distributed_SPICE-model_of_a_solar_cell,
You can get the relation by assuming Iph and calculating Im. Then plot Im as a function of Ip and get the relation between them as a best fit of staight line as
Im= consatnt Iph
Iph varies from around 30 to 40 mA/cm^2
Best wishes
@Zekry thank u so much, In the end, it's just an approximation..
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