[docs]
def fit_cec_sam(celltype, v_mp, i_mp, v_oc, i_sc, alpha_sc, beta_voc,
gamma_pmp, cells_in_series, temp_ref=25):
"""
Estimates parameters for the CEC single diode model (SDM) using the SAM
SDK.
Parameters
----------
celltype : str
Value is one of 'monoSi', 'multiSi', 'polySi', 'cis', 'cigs', 'cdte',
'amorphous'
v_mp : float
Voltage at maximum power point [V]
i_mp : float
Current at maximum power point [A]
v_oc : float
Open circuit voltage [V]
i_sc : float
Short circuit current [A]
alpha_sc : float
Temperature coefficient of short circuit current [A/C]
beta_voc : float
Temperature coefficient of open circuit voltage [V/C]
gamma_pmp : float
Temperature coefficient of power at maximum power point [%/C]
cells_in_series : int
Number of cells in series
temp_ref : float, default 25
Reference temperature condition [C]
Returns
-------
I_L_ref : float
The light-generated current (or photocurrent) at reference
conditions [A]
I_o_ref : float
The dark or diode reverse saturation current at reference
conditions [A]
R_s : float
The series resistance at reference conditions, in ohms.
R_sh_ref : float
The shunt resistance at reference conditions, in ohms.
a_ref : float
The product of the usual diode ideality factor ``n`` (unitless),
number of cells in series ``Ns``, and cell thermal voltage at
reference conditions [V]
Adjust : float
The adjustment to the temperature coefficient for short circuit
current, in percent.
Raises
------
ImportError
if NREL-PySAM is not installed.
RuntimeError
if parameter extraction is not successful.
Notes
-----
The CEC model and estimation method are described in [1]_.
Inputs ``v_mp``, ``i_mp``, ``v_oc`` and ``i_sc`` are assumed to be from a
single IV curve at constant irradiance and cell temperature. Irradiance is
not explicitly used by the fitting procedure. The irradiance level at which
the input IV curve is determined and the specified cell temperature
``temp_ref`` are the reference conditions for the output parameters
``I_L_ref``, ``I_o_ref``, ``R_s``, ``R_sh_ref``, ``a_ref`` and ``Adjust``.
References
----------
.. [1] A. Dobos, "An Improved Coefficient Calculator for the California
Energy Commission 6 Parameter Photovoltaic Module Model", Journal of
Solar Energy Engineering, vol 134, 2012. :doi:`10.1115/1.4005759`
"""
try:
from PySAM import PySSC
except ImportError:
raise ImportError("Requires NREL's PySAM package at "
"https://pypi.org/project/NREL-PySAM/.")
datadict = {'tech_model': '6parsolve', 'financial_model': None,
'celltype': celltype, 'Vmp': v_mp,
'Imp': i_mp, 'Voc': v_oc, 'Isc': i_sc, 'alpha_isc': alpha_sc,
'beta_voc': beta_voc, 'gamma_pmp': gamma_pmp,
'Nser': cells_in_series, 'Tref': temp_ref}
result = PySSC.ssc_sim_from_dict(datadict)
if result['cmod_success'] == 1:
return tuple([result[k] for k in ['Il', 'Io', 'Rs', 'Rsh', 'a',
'Adj']])
else:
raise RuntimeError('Parameter estimation failed')
