pvl_est_kappa_IEC60891_2

PVL_EST_KAPPA_IEC60891_2 Estimate the curve correction factor kappa for IEC 60891 method 2.

Contents

Syntax

kappa = pvl_est_kappa_IEC60891_2(IVCurves, aIsc, bVoc, Rs)

Description:

Methods in IEC60891 translates a point on an IV curve measured at irradiance G1 and cell temperature Tc1 to the corresponding point on an unobserved IV curve at irradiance G2 and cell temperature Tc2. The translation reduces the voltage value by a voltage drop across the ‘internal series resistance’ of the module ([IEC 60891], Eq. 2). A value for the curve correction factor interpreted as the temperature coefficient of the series resistance is found by interative search using a set of IV curves measured at different cell temperatures and at a common irradiance: first, voltage and current for each IV curve are translated to a common temperature, then kappa is found by minimizing the variance of Pmp of the translated IV curves.

pvl_est_kappa_IEC60891_2 assumes that the IV curves have been translated to a common irradiance.

Inputs:

Outputs:

Example

clearvars

% Set up parameters for a representative 60 cell cSi module using the Desoto model
Const.q = 1.60218E-19;
Const.k = 1.38066E-23;
Const.E0 = 1000;
Const.T0 = 25;

param.aIsc = 0.0008;  % A/C
param.bVoc = -0.1900; % V/C

param.Rs_ref = 0.2;
param.Rsh_ref = 1000;
param.IL_ref = 8.0;
param.I0_ref = 5e-10;

param.a_ref = 1.05 * 60 * Const.k/Const.q * (273.15 + Const.T0);

EgRef = 1.121;
dEgdT = -0.0002677;

% Calculate set of IV curves
Ee = 1000;
Tc = 25:1:35;
nPts = 100;
for i=1:length(Tc)
    [IL, I0, Rs, Rsh1, nNsVth] = pvl_calcparams_desoto(Ee, Tc(i), param.aIsc, param, EgRef, dEgdT);
    IVcurves(i) = pvl_singlediode(IL, I0, Rs, Rsh1, nNsVth, nPts);
end

% Add Ee and Tc to IVcurves
for i=1:length(Tc)
    IVcurves(i).Ee = Ee;
    IVcurves(i).Tc = Tc(i);
end

% Calculate relative temperature coefficients

STC_Isc = IVcurves(6).Isc;
STC_Voc = IVcurves(6).Voc;
aIsc_rel = param.aIsc / STC_Isc;
bVoc_rel = param.bVoc / STC_Voc;

% Use known Rs for the curve correction factor. Otherwise, estimate Rs from
% a set of IV curves with fixed temperature and varying irradiance, using
% pvl_est_Rs_IEC60891_2
Rs_est = param.Rs_ref;

% Estimate kappa
kappa = pvl_est_kappa_IEC60891_2(IVcurves, aIsc_rel, bVoc_rel, Rs_est)
kappa =

   -0.0045

References:

See also

pvl_est_Rs_IEC60891_2, pvl_translate_IV_curve_IEC60891_2

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