pvl_est_Rs_sunsVoc

PVL_EST_RS_SUNSVOC Estimate Rs using the suns-Voc method.

Contents

Syntax

Description:

The suns-Voc method estimates series resistance using the suns-Voc curve and a measured IV curve. It is assumed that both the suns-Voc and measured IV curves are at cell temperature of 25C. The suns-Voc curve is expressed as a pair of vectors (sunsV, sunsI) where sunsV is a vector of Voc at irradiance levels E, and sunsI = Isc0 - Isc(E) where Isc0 is the short circuit current at STC (1000 W/m2 and 25C). A point is selected on the (sunsV, sunsI) curve where the pseudo-current sunsI is equal to the measured Imp.

If optional arguments are provided, the difference between the returned Rs value and the Rs parameter for the single diode equation is estimated, see [2]. For this estimate, shunt resistance and short circuit current are required for the IV curve at irradiance E = (1 - Imp / Isc0)*1000 W/m2.

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 IV curve at STC
Ee = 1000;
Tc = 25;
nPts = 100;
[IL, I0, Rs, Rshf, nNsVth] = pvl_calcparams_desoto(Ee, Tc, param.aIsc, param, EgRef, dEgdT);
IVcurve_STC = pvl_singlediode(IL, I0, Rs, Rshf, nNsVth, nPts);


% simulate suns-Voc curve
suns = 10:10:1000; suns = suns(:);
sunsTc = ones(size(suns)).*25;
sunsIsc0 = IVcurve_STC.Isc;
sunsIsc = suns./1000.*sunsIsc0;

[IL, I0, Rs, Rsh, nNsVth] = pvl_calcparams_desoto(suns, sunsTc, param.aIsc, param, EgRef, dEgdT);
res = pvl_singlediode(IL, I0, Rs, Rsh, nNsVth, nPts);
sunsVoc.V = [res(:).Voc];
sunsVoc.I = (1 - suns(:)/1000)*sunsIsc0;

% Estimate Rs
Rs = pvl_est_Rs_sunsVoc(sunsVoc.V, sunsVoc.I, IVcurve_STC.Isc, IVcurve_STC.Vmp, IVcurve_STC.Imp)
Rs =

    0.2144

References:

See also

pvl_est_Rs_Bowden , pvl_est_Rs_Swanson , pvl_est_Rs_Pysch , pvl_est_Rs_IEC60891_1 , pvl_est_Rs_IEC60891_2

Copyright 2018 Sandia National Laboratories