pvlib.pvsystem.sapm

pvlib.pvsystem.sapm(effective_irradiance, temp_cell, module)[source]

The Sandia PV Array Performance Model (SAPM) generates 5 points on a PV module’s I-V curve (Voc, Isc, Ix, Ixx, Vmp/Imp) according to SAND2004-3535. Assumes a reference cell temperature of 25 C.

Parameters:

effective_irradiance : numeric

Effective irradiance (suns).

temp_cell : numeric

The cell temperature (degrees C).

module : dict-like

A dict, Series, or DataFrame defining the SAPM performance parameters. See the notes section for more details.

Returns:

A DataFrame with the columns:

  • i_sc : Short-circuit current (A)
  • i_mp : Current at the maximum-power point (A)
  • v_oc : Open-circuit voltage (V)
  • v_mp : Voltage at maximum-power point (V)
  • p_mp : Power at maximum-power point (W)
  • i_x : Current at module V = 0.5Voc, defines 4th point on I-V curve for modeling curve shape
  • i_xx : Current at module V = 0.5(Voc+Vmp), defines 5th point on I-V curve for modeling curve shape

Notes

The coefficients from SAPM which are required in module are listed in the following table.

The modules in the Sandia module database contain these coefficients, but the modules in the CEC module database do not. Both databases can be accessed using retrieve_sam().

Key Description
A0-A4 The airmass coefficients used in calculating effective irradiance
B0-B5 The angle of incidence coefficients used in calculating effective irradiance
C0-C7 The empirically determined coefficients relating Imp, Vmp, Ix, and Ixx to effective irradiance
Isco Short circuit current at reference condition (amps)
Impo Maximum power current at reference condition (amps)
Aisc Short circuit current temperature coefficient at reference condition (1/C)
Aimp Maximum power current temperature coefficient at reference condition (1/C)
Bvoco Open circuit voltage temperature coefficient at reference condition (V/C)
Mbvoc Coefficient providing the irradiance dependence for the BetaVoc temperature coefficient at reference irradiance (V/C)
Bvmpo Maximum power voltage temperature coefficient at reference condition
Mbvmp Coefficient providing the irradiance dependence for the BetaVmp temperature coefficient at reference irradiance (V/C)
N Empirically determined “diode factor” (dimensionless)
Cells_in_Series Number of cells in series in a module’s cell string(s)
IXO Ix at reference conditions
IXXO Ixx at reference conditions
FD Fraction of diffuse irradiance used by module

References

[1] King, D. et al, 2004, “Sandia Photovoltaic Array Performance Model”, SAND Report 3535, Sandia National Laboratories, Albuquerque, NM.