# pvlib.temperature.fuentes¶

pvlib.temperature.fuentes(poa_global, temp_air, wind_speed, noct_installed, module_height=5, wind_height=9.144, emissivity=0.84, absorption=0.83, surface_tilt=30, module_width=0.31579, module_length=1.2)[source]

Calculate cell or module temperature using the Fuentes model.

The Fuentes model is a first-principles heat transfer energy balance model 1 that is used in PVWatts for cell temperature modeling 2.

Parameters
• poa_global (pandas Series) – Total incident irradiance [W/m^2]

• temp_air (pandas Series) – Ambient dry bulb temperature [C]

• wind_speed (pandas Series) – Wind speed [m/s]

• noct_installed (float) – The “installed” nominal operating cell temperature as defined in 1. PVWatts assumes this value to be 45 C for rack-mounted arrays and 49 C for roof mount systems with restricted air flow around the module. [C]

• module_height (float, default 5.0) – The height above ground of the center of the module. The PVWatts default is 5.0 [m]

• wind_height (float, default 9.144) – The height above ground at which wind_speed is measured. The PVWatts defauls is 9.144 [m]

• emissivity (float, default 0.84) – The effectiveness of the module at radiating thermal energy. [unitless]

• absorption (float, default 0.83) – The fraction of incident irradiance that is converted to thermal energy in the module. [unitless]

• surface_tilt (float, default 30) – Module tilt from horizontal. If not provided, the default value of 30 degrees from 1 and 2 is used. [degrees]

• module_width (float, default 0.31579) – Module width. The default value of 0.31579 meters in combination with the default module_length gives a hydraulic diameter of 0.5 as assumed in 1 and 2. [m]

• module_length (float, default 1.2) – Module length. The default value of 1.2 meters in combination with the default module_width gives a hydraulic diameter of 0.5 as assumed in 1 and 2. [m]

Returns

temperature_cell (pandas Series) – The modeled cell temperature [C]

Notes

This function returns slightly different values from PVWatts at night and just after dawn. This is because the SAM SSC assumes that module temperature equals ambient temperature when irradiance is zero so it can skip the heat balance calculation at night.

References

1(1,2,3,4,5)

Fuentes, M. K., 1987, “A Simplifed Thermal Model for Flat-Plate Photovoltaic Arrays”, SAND85-0330, Sandia National Laboratories, Albuquerque NM. http://prod.sandia.gov/techlib/access-control.cgi/1985/850330.pdf

2(1,2,3,4)

Dobos, A. P., 2014, “PVWatts Version 5 Manual”, NREL/TP-6A20-62641, National Renewable Energy Laboratory, Golden CO. doi:10.2172/1158421.