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) – Irradiance reaching the module’s cells, after reflections and adjustment for spectrum. [W/m2]

  • temp_cell (numeric) – Cell temperature [C].

  • module (dict-like) – A dict or Series defining the SAPM 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 SAPM parameters which are required in module are listed in the following table.

The Sandia module database contains parameter values for a limited set of modules. The CEC module database does not contain these parameters. 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)

Voco

Open circuit voltage at reference condition (amps)

Vmpo

Maximum power voltage 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.