"""
Tandem Solar Cell under STC
===========================
Simulating the IV curve of a Tandem Solar Cell with a 1-Diode model.
"""

# %%
# This example shows how to model the performance of a tandem solar cell. It
# uses "spectral-on-demand" data from the NSRDB providded by NREL.
# For the absorptances of the subcells GENPRO4 simulated EQE curves are used
# originally createf for the following publication:
# Reference
# ----------
# .. [1] P. Tillmann, K. Jäger, A. Karsenti, L. Kreinin, C. Becker (2022)
#    “Model-Chain Validation for Estimating the Energy Yield of Bifacial
#    Perovskite/Silicon Tandem Solar Cells,” Solar RRL 2200079,
#    DOI: 10.1002/solr.202200079

# %%
# First, we load the preprocessed spectral and meta-data (for temperature)
# The spectral data has to be converted from W/µm/m2 to W/nm/m2 (by deviding by 1000)

import pandas as pd
import numpy as np
import matplotlib.pyplot as plt
from pv_tandem import utils, solarcell_models
import pvlib

plt.rcParams["figure.dpi"] = 140

eqe = pd.read_csv("./data/eqe_tandem_2t.csv", index_col=0)


# %%
# Note that the airmass and zenith values do not exactly match the values in
# the technical report; this is because airmass is estimated from solar
# position and the solar position calculation in the technical report does not
# exactly match the one used here.  However, the differences are minor enough
# to not materially change the spectra.


electrical_parameters = {
    "Rsh": {"pero": 2000, "si": 5000},
    "Rs": {"pero":6, "si":2},
    "j0": {"pero": 2.7e-18, "si": 1e-12},
    "n": {"pero": 1.1, "si": 1},
    "Temp": {"pero": 25, "si": 25},
    "noct": {"pero": 48, "si": 48},
    "tcJsc": {"pero": 0.0002, "si": 0.00032},
    "tcVoc": {"pero": -0.002, "si": -0.0041},
}

tandem = solarcell_models.TandemSimulator4T(
    eqe=eqe,
    electrical_parameters=electrical_parameters,
    subcell_names=["pero", "si"],
)

iv_stc = tandem.calc_IV_stc()

fig, ax = plt.subplots()

for subcell, iv in iv_stc.items():
    iv = iv[(iv > 0).shift(1, fill_value=True)]
    iv = iv.reset_index().set_index(subcell)
    iv.plot(ax=ax)

ax.legend(["Perovskite", "Silicon"])
ax.set_xlabel("Voltage (V)")
ax.set_ylabel("Current density (mA/cm2)")
ax.set_xlim(0)
ax.set_ylim(0)
plt.show()