/
MJ_solar_cell_3J_efficiency_map.py
executable file
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/
MJ_solar_cell_3J_efficiency_map.py
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import numpy as np
import matplotlib.pyplot as plt
from matplotlib import cm
from solcore.light_source import LightSource
from solcore.solar_cell import SolarCell
from solcore.solar_cell_solver import solar_cell_solver
from solcore.structure import Junction
# Illumination spectrum
wl = np.linspace(300, 4000, 4000) * 1e-9
light = LightSource(
source_type="standard", version="AM1.5g", x=wl, output_units="photon_flux_per_m"
)
T = 298
V = np.linspace(0, 5, 500)
# This function assembles the solar cell and calculates the IV cruve
def solve_MJ(EgBot, EgMid, EgTop):
db_junction0 = Junction(kind="DB", T=T, Eg=EgBot, A=1, R_shunt=np.inf, n=3.5)
db_junction1 = Junction(kind="DB", T=T, Eg=EgMid, A=1, R_shunt=np.inf, n=3.5)
db_junction2 = Junction(kind="DB", T=T, Eg=EgTop, A=1, R_shunt=np.inf, n=3.5)
my_solar_cell = SolarCell(
[db_junction2, db_junction1, db_junction0], T=T, R_series=0
)
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,
},
)
return my_solar_cell
# We create an efficiency map using Eg0 as the bandgap of the bottom junction and
# scanning the bandgaps of the middle and top junctions. Increase N1 and N2 to have
# higher resolution.
N1 = 10
N2 = 10
Eg0 = 1.12
all_Eg1 = np.linspace(1.3, 1.8, N1)
all_Eg2 = np.linspace(1.7, 2.4, N2)
eff = np.zeros((N1, N2))
N = N1 * N2
index = 0
Effmax = -1
Eg1_max = all_Eg1[0]
Eg2_max = all_Eg2[0]
# And we run the calculation
for i, Eg1 in enumerate(all_Eg1):
for j, Eg2 in enumerate(all_Eg2):
my_solar_cell = solve_MJ(Eg0, Eg1, Eg2)
mpp = my_solar_cell.iv.Pmpp
eff[i, j] = mpp
if mpp > Effmax:
Effmax = mpp
Eg1_max = Eg1
Eg2_max = Eg2
index += 1
print(int(index / N * 100), "%\n")
optimum_MJ = solve_MJ(Eg0, Eg1_max, Eg2_max)
plt.figure(1)
plt.plot(V, optimum_MJ.iv.IV[1], "k", linewidth=4, label="Total")
plt.plot(V, -optimum_MJ[0].iv(V), "r", label="Bottom")
plt.plot(V, -optimum_MJ[1].iv(V), "g", label="Middle")
plt.plot(V, -optimum_MJ[2].iv(V), "b", label="Top")
plt.ylim(0, 200)
plt.xlim(0, 3.75)
plt.legend()
plt.xlabel("Voltage (V)")
plt.ylabel("Current (A/m$^2$)")
plt.figure(2)
eff = eff / light.power_density * 100
plt.contourf(all_Eg2, all_Eg1, eff, 50, cmap=cm.jet)
plt.xlabel("TOP Eg (eV)")
plt.ylabel("MID Eg (eV)")
cbar = plt.colorbar()
cbar.set_label("Efficiency (%)", rotation=270, labelpad=10)
plt.tight_layout()
plt.show()