pvl_singlediode

Solve the single-diode equation to obtain a photovoltaic IV curve.

Contents

Syntax

[Result] = pvl_singlediode(IL, I0, Rs, Rsh, nNsVth)

[Result] = pvl_singlediode(IL, I0, Rs, Rsh, nNsVth, NumPoints)

Description

pvl_singlediode solves the single diode equation [1]:

$$I = I_L - I_0 \left(\exp \left({\frac{V+IR_s}{nNsVth}}\right)- 1\right) - {\frac{V +
IR_s}{R_{sh}}} $$

for I and V when given IL, I0, Rs, Rsh, and nNsVth (nNsVth = n Ns Vth). The numerical solution uses a formulation [2] of the single diode equation in terms of the Lambert W function. pvl_singlediode returns a struct which contains the five points on the I-V curve specified in the Sandia Array Performance Model [3], and can optionally return vectors of I and V describing the full IV curve with a user-defined number of points. If IL, I0, Rs, Rsh, and nNsVth are scalars, a single IV curve will be returned; if any inputs are vectors (of the same length), multiple IV curves will be calculated.

Inputs

Output

Notes

  1. To plot the ith IV curve, use: plot(Result.V(i,:), Result.I(i,:))
  2. To plot all IV curves on the same plot: plot(Result.V', Result.I')
  3. Generating IV curves using NumPoints will slow down function operation.

Example

Example parameters for a typical 210 W c-Si module

IL = 5.658; %photocurrent (A)
I0 = 4.629E-11; %dark current (A)
Rsh = 269.68; %shunt resistance (ohms)
Rs = .386; %series resistance (ohms)
n = 1.0134; % ideality factor (diode factor)
Ns = 72; %number of cells in series
k = 1.3806488E-23; %Boltzman's constant in units of J/K
Tcell = 25; %deg C
q = 1.60217646E-19; %Electron charge in coulombs
nVth = n*Ns*k*(Tcell+273.15)/q;
NumPoints = 1000;
[IVResult] = pvl_singlediode(IL, I0, Rs, Rsh, nVth, NumPoints);

figure
plot(IVResult.V,IVResult.I)
hold on
scatter(IVResult.Vmp,IVResult.Imp,'filled')
xlabel('Voltage (V)')
ylabel('Current (A)')
title('Example IV Curve from Single Diode Model','FontSize',14)
Pmax = IVResult.Pmp %Max Power of Module
Pmax =

  210.0013

References:

[1] S.R. Wenham, M.A. Green, M.E. Watt, "Applied Photovoltaics" ISBN 0 86758 909 4

[2] A. Jain, A. Kapoor, 2004. Exact analytical solutions of the parameters of real solar cells using Lambert W-function, Solar Energy Materials and Solar Cells, 81 (2004) 269-277.

[3] D. King et al, "Sandia Photovoltaic Array Performance Model", SAND2004-3535, Sandia National Laboratories, Albuquerque, NM

See also

pvl_calcparams_desoto, pvl_calcparams_PVsyst, pvl_calcparams_CEC, pvl_lambertw, pvl_sapm.

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