Specifying J01 and J02 for the 2D junction solver

[iclned]

The 2-diode (2D) junction solver is presently configured using Eg to set J01 and a radiative efficiency to set J02. This is quite limiting since it is often useful to specify J01 and J02 explicitly, not calculate them from Eg and radiative efficiency!
It should be possible to set J01 and J02 directly in the Junction () definition.

[dalonsoa]

This is not really correct. As shown from this line, if there's no need to specify Eg: you can define the junction using j01 and j02. The bandgap is needed only if the reference temperature is different than the working temprature.

If you create a junction providing j01 and j02, do you get and error? If so, could you post it?

[iclned]

Here's the code. Changing j01 makes no difference to the results. If I remove the Eg= statements SolCore throws an error "ERROR in 2-diode equation. Junction is missing one essential argument. ERROR calculating the IV for the detailed balance Junction kind. Junction is missing one essential argument: 'Junction' object has no attribute 'Eg' "

import numpy as np

from solcore.solar_cell import SolarCell
from solcore.light_source import LightSource
from solcore.solar_cell_solver import solar_cell_solver
from solcore.structure import Junction
from solcore.spice.pv_module_solver import spice_junction
from solcore.spice.pv_module_solver import solve_pv_module

# Code to use the internal SolCore solver
def dsolver( concX,iscarray,j01array ):
    T=273+25
# First we define the properties of the MJ solar cell that the solar module is made of. We use junctions of kind 2-diode
    ge_junction = Junction(kind='2D', T=T, reff=1, jref=300, Eg=0.66, A=1, R_series=0.000, R_shunt=1e14, n=3.5,jsc=10*iscarray[2]*concX, j01=j01array[2])
    ingaas_junction = Junction(kind='2D', T=T, reff=1, jref=300, Eg=1.4, A=1, R_series=0.00, R_shunt=1e14, n=3.5,jsc=10*iscarray[1]*concX, j01=j01array[1])
    ingap_junction = Junction(kind='2D', T=T, reff=1, jref=300,Eg=1.9, A=1, R_series=0, R_shunt=1e14, n=3.5, jsc=10 * iscarray[0] * concX, j01=j01array[0])
#Assemble a solar cell from these juctions
#    my_solar_cell = SolarCell([ingap_junction, ingaas_junction, ge_junction], T=T, R_series=0.0, area=0.1)
    my_solar_cell = SolarCell([ingap_junction],T=T, R_series=0.0, area=1e-4)
    wl = np.linspace(350, 2000, 301) * 1e-9
    light_source = LightSource(source_type='standard', version='AM1.5d', x=wl, output_units='photon_flux_per_m',
                               concentration=concX)

    # options = {'light_iv': True, 'wavelength': wl, 'light_source': light_source}
    V = np.linspace(0, 5, 500)
    solar_cell_solver(my_solar_cell, 'iv',
                          user_options={'T_ambient': T, 'db_mode': 'top_hat', 'voltages': V, 'light_iv': True,
                                        'internal_voltages': np.linspace(-6, 5, 1100), 'wavelength': wl,
                                        'mpp': True, 'light_source': light_source})

    efficiency=my_solar_cell.iv["Eta"]
    pmax=my_solar_cell.iv["Pmpp"]
    ff=my_solar_cell.iv["FF"]
    voc=my_solar_cell.iv["Voc"]
    isc=my_solar_cell.iv["Isc"]

    return [concX,isc,voc,ff,efficiency,pmax]

print(dsolver(200,[14,14,17],[5E-27,6E-19,4.93E-6]))
print(dsolver(200,[14,14,17],[5E-26,6E-18,4.93E-5]))

[dalonsoa]

The problem is that you also provide the radiative efficiency. When that happens, the program assumes you want to go fully fundamental and calculates j01 using the detail balance. That’s why it raises an error.

Have a look at this file. The problem is not complicated to solve and should require either adding another branch to the off statement or - even better - reformulating how the two diode kind of junction is defined, including explicit inputs, as we discussed the other day.

[dalonsoa]

In summary, I believe we have the following set of possible inputs for the Junction (I think):

• j01, j02, n1, n2, Rseries, Rshunt
• j01, reff, n1, n2, Rseries, Rshunt
• Eg, reff, n1, n2, Rseries, Rshunt, T

At the moment, we’re missing the second option.