pvdeg.degradation.arrhenius#

pvdeg.degradation.arrhenius(weather_df=None, temperature=None, RH=None, irradiance=None, elapsed_time=None, Ro=1, Ea=0, p=0, n=0, C2=0, parameters=None)[source]#

Calculate the degradation rate using an Arrhenius function with power law functions for humidity and irradiance dependence.

D = R_0 ∫[RH(t)]^n·e^[-E_a/RT(t)] {∫[e^(-C_2∙λ)∙G(λ,t)]^p dλ}dt

Parameters:

  • weather_df (pd.DataFrame) – Dataframe containing temperature, humidity, and irradiance data. Defaults to module surface temperature, surface humidity, and POA global irradiance.

  • temperature (pd.DataFrame) – Temperature data for Arrhenius degradation calculation. If not specified, uses module surface temperature from weather_df. If Ea=0, temperature is not needed.

  • RH (pd.DataFrame) – Relative humidity data for Arrhenius degradation calculation. If not specified, uses module surface relative humidity from weather_df. If n=0, humidity is not needed.

  • irradiance (pd.DataFrame) – Irradiance data for Arrhenius degradation calculation. If not specified, uses module POA irradiance from weather_df. If p=0, irradiance is not needed. If C2 is provided, wavelength spectral intensity data must be provided. The header should start with “spectra”, followed by wavelength points. Each element is a list of intensity values at each wavelength [W/m²/nm].

  • elapsed_time (pd.DataFrame) – If the time step for each interval is not constant, this can be used to provide a different elapsed time value for each element. If it is included in the weather_df, it must be under a column named “elapsed_time”.

  • Ro (float) – Degradation rate prefactor [e.g. %/h/%RH/(1000 W/m²)]. Defaults to 1 if not provided.

  • Ea (float) – Degradation Activation Energy [kJ/mol]. If Ea=0, no temperature dependence and degradation will proceed according to the amount of light an humidity.

  • p (float) – Power law coefficient for irradiance dependence. If p=0, ignores light. Small p (e.g. 0.0001) means little dependence of degradation on irradiance, but only daylight is considered.

  • n (float) – Power law coefficient for humidity dependence. If n=0, ignores humidity.

  • C2 (float) – Coefficient for spectral response dependence on wavelength.

  • parameters (json) – Database containing parameters for Arrhenius calculation. If Ea, n, or p are not provided, values are taken from this json database.

Returns:

degradation (float) – Total degradation with units as determined by Ro.

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