pvlib.snow.coverage_nrel#

pvlib.snow.coverage_nrel(snowfall, poa_irradiance, temp_air, surface_tilt, snow_depth=None, initial_coverage=0, threshold_snowfall=1.0, threshold_depth=1.0, can_slide_coefficient=-80.0, slide_amount_coefficient=0.197)[source]#

Calculates the fraction of the slant height of a row of modules that is covered by snow at every time step.

Implements the model described in [1] with minor improvements in [2], with the change that the output is in fraction of the row’s slant height rather than in tenths of the row slant height. As described in [1], model validation focused on fixed tilt systems.

Parameters:

snowfall (Series) – Snowfall within each time period. [cm]
poa_irradiance (Series) – Total in-plane irradiance [W/m^2]
temp_air (Series) – Ambient air temperature [C]
surface_tilt (numeric) – Tilt of module’s from horizontal, e.g. surface facing up = 0, surface facing horizon = 90. [degrees]
snow_depth (Series, optional) – Snow depth on the ground at the beginning of each time period. Must have the same index as snowfall. [cm]
initial_coverage (float, default 0) – Fraction of row’s slant height that is covered with snow at the beginning of the simulation. [unitless]
threshold_snowfall (float, default 1.0) – Hourly snowfall above which the row is fully covered for that hour. [cm/hr]
threshold_depth (float, default 1.0) – Snow depth on the ground, above which snow can affect the modules. [cm]
can_slide_coefficient (float, default -80.) – Coefficient to determine if snow can slide given irradiance and air temperature. [W/(m^2 C)]
slide_amount_coefficient (float, default 0.197) – Coefficient to determine fraction of snow that slides off in one hour. [unitless]

Returns:

snow_coverage (Series) – The fraction of the slant height of a row of modules that is covered by snow at each time step.

Notes

In [1], can_slide_coefficient is termed m, and the value of slide_amount_coefficient is given in tenths of a module’s slant height.

snow_depth is used to set snow_coverage to 0 (not fully covered) when snow is less than threshold_depth. This check is described in [2] as needed for systems with low tilt angle.

References