# pvlib.pvsystem.calcparams_cec¶

pvlib.pvsystem.calcparams_cec(effective_irradiance, temp_cell, alpha_sc, a_ref, I_L_ref, I_o_ref, R_sh_ref, R_s, Adjust, 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 CEC model. The CEC model 1 differs from the De soto et al. model 3 by the parameter Adjust. The five values returned by calcparams_cec 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.

• Adjust (float) – The adjustment to the temperature coefficient for short circuit current, in percent

• 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 [3]) 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.

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.

2

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

3

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