pvlib.pvsystem.calcparams_desoto

pvlib.pvsystem.calcparams_desoto(effective_irradiance, temp_cell, alpha_sc, a_ref, I_L_ref, I_o_ref, R_sh_ref, R_s, EgRef=1.121, dEgdT=-0.0002677, irrad_ref=1000, temp_ref=25)[source]

Calculates five parameter values for the single diode equation at effective irradiance and cell temperature using the De Soto et al. model described in [1]. The five values returned by calcparams_desoto can be used by singlediode to calculate an IV curve.

Parameters:
effective_irradiance : numeric

The irradiance (W/m2) that is converted to photocurrent.

temp_cell : numeric

The average cell temperature of cells within a module in C.

alpha_sc : float

The short-circuit current temperature coefficient of the module in units of A/C.

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, in units of V.

I_L_ref : float

The light-generated current (or photocurrent) at reference conditions, in amperes.

I_o_ref : float

The dark or diode reverse saturation current at reference conditions, in amperes.

R_sh_ref : float

The shunt resistance at reference conditions, in ohms.

R_s : float

The series resistance at reference conditions, in ohms.

EgRef : float

The energy bandgap at reference temperature in units of eV. 1.121 eV for crystalline silicon. EgRef must be >0. For parameters from the SAM CEC module database, EgRef=1.121 is implicit for all cell types in the parameter estimation algorithm used by NREL.

dEgdT : float

The temperature dependence of the energy bandgap at reference conditions in units of 1/K. May be either a scalar value (e.g. -0.0002677 as in [1]) or a DataFrame (this may be useful if dEgdT is a modeled as a function of temperature). For parameters from the SAM CEC module database, dEgdT=-0.0002677 is implicit for all cell types in the parameter estimation algorithm used by NREL.

irrad_ref : float (optional, default=1000)

Reference irradiance in W/m^2.

temp_ref : float (optional, default=25)

Reference cell temperature in C.
Returns:
Tuple of the following results:
photocurrent : numeric

Light-generated current in amperes

saturation_current : numeric

Diode saturation curent in amperes

resistance_series : float

Series resistance in ohms

resistance_shunt : numeric

Shunt resistance in ohms

nNsVth : numeric

The product of the usual diode ideality factor (n, unitless), number of cells in series (Ns), and cell thermal voltage at specified effective irradiance and cell temperature.

See also

singlediode, retrieve_sam

Notes

If the reference parameters in the ModuleParameters struct are read from a database or library of parameters (e.g. System Advisor Model), it is important to use the same EgRef and dEgdT values that were used to generate the reference parameters, regardless of the actual bandgap characteristics of the semiconductor. For example, in the case of the System Advisor Model library, created as described in [3], EgRef and dEgdT for all modules were 1.121 and -0.0002677, respectively.

This table of reference bandgap energies (EgRef), bandgap energy temperature dependence (dEgdT), and “typical” airmass response (M) is provided purely as reference to those who may generate their own reference module parameters (a_ref, IL_ref, I0_ref, etc.) based upon the various PV semiconductors. Again, we stress the importance of using identical EgRef and dEgdT when generation reference parameters and modifying the reference parameters (for irradiance, temperature, and airmass) per DeSoto’s equations.

Crystalline Silicon (Si):
  • EgRef = 1.121
  • dEgdT = -0.0002677
>>> M = np.polyval([-1.26E-4, 2.816E-3, -0.024459, 0.086257, 0.9181],
...                AMa) # doctest: +SKIP

Source: [1]

Cadmium Telluride (CdTe):
  • EgRef = 1.475
  • dEgdT = -0.0003
>>> M = np.polyval([-2.46E-5, 9.607E-4, -0.0134, 0.0716, 0.9196],
...                AMa) # doctest: +SKIP

Source: [4]

Copper Indium diSelenide (CIS):
  • EgRef = 1.010
  • dEgdT = -0.00011
>>> M = np.polyval([-3.74E-5, 0.00125, -0.01462, 0.0718, 0.9210],
...                AMa) # doctest: +SKIP

Source: [4]

Copper Indium Gallium diSelenide (CIGS):
  • EgRef = 1.15
  • dEgdT = ????
>>> M = np.polyval([-9.07E-5, 0.0022, -0.0202, 0.0652, 0.9417],
...                AMa) # doctest: +SKIP

Source: Wikipedia

Gallium Arsenide (GaAs):
  • EgRef = 1.424
  • dEgdT = -0.000433
  • M = unknown

Source: [4]

References

[1] W. De Soto et al., “Improvement and validation of a model for photovoltaic array performance”, Solar Energy, vol 80, pp. 78-88, 2006.

[2] System Advisor Model web page. https://sam.nrel.gov.

[3] A. Dobos, “An Improved Coefficient Calculator for the California Energy Commission 6 Parameter Photovoltaic Module Model”, Journal of Solar Energy Engineering, vol 134, 2012.

[4] O. Madelung, “Semiconductors: Data Handbook, 3rd ed.” ISBN 3-540-40488-0