pvdeg.degradation.IwaArrhenius

pvdeg.degradation.IwaArrhenius(weather_df: DataFrame, meta: dict, rh_outdoor: Series, Ea: float, poa: DataFrame = None, temp: Series = None, RHwa: float = None, Teq: float = None, p: float = 0.5, n: float = 1, temp_model='sapm', conf='open_rack_glass_polymer', wind_factor=0.33, model_kwarg={}, irradiance_kwarg={}) → float

Function to calculate IWa, the Environment Characterization [W/m²]. For one year of degradation the controlled environment lamp settings will need to be set at IWa.

Parameters:

• weather_df (pd.DataFrame) – Dataframe containing at least dni, dhi, ghi, temperature, wind_speed

• meta (dict) – Location meta-data containing at least latitude, longitude, altitude

• rh_outdoor (pd.Series) – Relative Humidity of material of interest Acceptable relative humiditys can be calculated from these functions: - pvdeg.humidity.backsheet() - pvdeg.humidity.back_encapsulant() - pvdeg.humidity.front_encapsulant() - pvdeg.humidity.surface_relative()

• Ea (float) – Degradation Activation Energy [kJ/mol]

• poa (pd.DataFrame, optional) – must contain ‘poa_global’, Global Plane of Array irradiance [W/m²]

• temp (pd.Series, optional) – Solar module temperature or Cell temperature [°C]

• RHwa (float, optional) – Relative Humidity Weighted Average [%]

• Teq (float, optional) – Temperature equivalent (Celsius) required for the settings of the controlled environment

• p (float) – Fit parameter

• n (float) – Fit parameter for relative humidity

• temp_model ((str, optional)) – Specify which temperature model from pvlib to use. Current options:

• conf ((str)) –

  The configuration of the PV module architecture and mounting configuration. Currently only used for ‘sapm’ and ‘pvsys’. With different options for each.

  ’sapm’ options: open_rack_glass_polymer (default), open_rack_glass_glass, close_mount_glass_glass, insulated_back_glass_polymer

  ’pvsys’ options: freestanding, insulated

• wind_factor (float, optional) – Wind speed correction exponent to account for different wind speed measurement heights between weather database (e.g. NSRDB) and the temperature model (e.g. SAPM) The NSRDB provides calculations at 2 m (i.e module height) but SAPM uses a 10 m height. It is recommended that a power-law relationship between height and wind speed of 0.33 be used*. This results in a wind speed that is 1.7 times higher. It is acknowledged that this can vary significantly.

• irradiance_kwarg ((dict, optional)) – keyword argument dictionary used for the poa irradiance calculation. options: sol_position, tilt, azimuth, sky_model. See pvdeg.spectral.poa_irradiance.

• model_kwarg ((dict, optional)) – keyword argument dictionary used for the pvlib temperature model calculation. See https://pvlib-python.readthedocs.io/en/stable/reference/pv_modeling/temperature.html # noqa for more.

Returns:

Iwa (float) – Environment Characterization [W/m²]