MJ_solar_cell_with_radiative_coupling.py

import matplotlib.pyplot as plt
import numpy as np

from solcore.structure import Junction
from solcore.solar_cell import SolarCell
from solcore.light_source import LightSource
from solcore.solar_cell_solver import solar_cell_solver
from solcore.graphing.Custom_Colours import colours

# TODO This needs some explanations/descriptions

T = 298

Vin = np.linspace(-6, 2, 600)
V = np.linspace(-1.5, 4, 500)
wl = np.linspace(350, 2000, 301) * 1e-9
light_source = LightSource(source_type='standard', version='AM1.5g', x=wl, output_units='photon_flux_per_m',
                           concentration=1)

color = ['b', 'g', 'r']
label = ['Top', 'Mid', 'Bot']

fig, ax = plt.subplots(1, 2, sharey='all', figsize=(7, 4.5))

for k, rad in enumerate([False, True]):

    # Input data for the 2D kind of junction
    db_junction = Junction(kind='2D', T=T, reff=0.3, jref=300, Eg=0.66, A=1, R_shunt=np.inf, n=3.5)
    db_junction2 = Junction(kind='2D', T=T, reff=1, jref=300, Eg=1.4, A=1, R_shunt=np.inf, n=3.5)
    db_junction3 = Junction(kind='2D', T=T, reff=1, jref=300, Eg=1.8, A=1, R_shunt=np.inf, n=3.5)

    my_solar_cell = SolarCell([db_junction3, db_junction2, db_junction], T=T, R_series=0)

    solar_cell_solver(my_solar_cell, 'iv',
                      user_options={'T_ambient': T, 'voltages': V, 'light_iv': True, 'wavelength': wl,
                                    'light_source': light_source, 'radiative_coupling': rad, 'mpp': True,
                                    'internal_voltages': Vin})

    # This is the total junction IV
    ax[k].plot(my_solar_cell.iv['IV'][0], my_solar_cell.iv['IV'][1], marker='o', color=colours("Black"), ls='-',
               markerfacecolor='none', markeredgecolor=colours("Black"))

    # This is the junciton IV when it is in the MJ device, including coupling if it is enabled. 
    for i, data in enumerate(my_solar_cell.iv['junction IV']):
        ax[k].plot(data[0], data[1], color[i] + '--', linewidth=2)

    # This is the junction IV as if it were an isolated device and therefore not affected by coupling or current limiting. 
    for i in range(my_solar_cell.junctions):
        ax[k].plot(V, -my_solar_cell(i).iv(V), color[i], linewidth=2, label=label[i])

    ax[k].set_ylim(0, 300)
    ax[k].set_xlim(0, 3.5)

    ax[k].set_xlabel('Bias (V)')

    Isc = my_solar_cell.iv["Isc"]
    Voc = my_solar_cell.iv["Voc"]
    FF = my_solar_cell.iv["FF"] * 100
    Eta = my_solar_cell.iv["Eta"] * 100

    ax[k].text(1.75, 275, 'I$_{sc}$ = ' + str(round(Isc, 1)) + ' A/m$^2$', fontsize=12)
    ax[k].text(1.75, 250, 'V$_{oc}$ = ' + str(round(Voc, 2)) + ' V', fontsize=12)
    ax[k].text(1.75, 225, 'FF = {:.1f} %'.format(FF), fontsize=12)
    ax[k].text(1.75, 200, r'$\eta$ = {:.1f} %'.format(Eta), fontsize=12)

ax[0].set_ylabel('Current (A/m$^2$)')
ax[0].text(0.9, 0.05, '(a)', transform=ax[0].transAxes, fontsize=12)
ax[1].text(0.9, 0.05, '(b)', transform=ax[1].transAxes, fontsize=12)
plt.tight_layout()
ax[0].legend(loc=(0.10, 0.80), frameon=False)
plt.show()