plot_greensboro_kimber_soiling.py

"""
Kimber Soiling Model
====================

Examples of soiling using the Kimber model.
"""

# %%
# This example shows basic usage of pvlib's Kimber Soiling model [1]_ with
# :py:meth:`pvlib.losses.soiling_kimber`.
#
# References
# ----------
# .. [1] "The Effect of Soiling on Large Grid-Connected Photovoltaic Systems
#    in California and the Southwest Region of the United States," Adrianne
#    Kimber, et al., IEEE 4th World Conference on Photovoltaic Energy
#    Conference, 2006, :doi:`10.1109/WCPEC.2006.279690`
#
# The Kimber Soiling model assumes that soiling builds up at a constant rate
# until cleaned either manually or by rain. The rain must reach a threshold to
# clean the panels. When rains exceeds the threshold, it's assumed the earth is
# damp for a grace period before it begins to soil again. There is a maximum
# soiling build up that cannot be exceeded even if there's no rain or
# manual cleaning.
#
# Threshold
# ---------
# The example shown here demonstrates how the threshold affects soiling.
# Because soiling depends on rainfall, loading weather data is always the first
# step.

from datetime import datetime
import pathlib
from matplotlib import pyplot as plt
from pvlib.iotools import read_tmy3, fix_tmy3_coerce_year_monotonicity
from pvlib.losses import soiling_kimber
import pvlib

# get full path to the data directory
DATA_DIR = pathlib.Path(pvlib.__file__).parent / 'data'

# get TMY3 data with rain
greensboro, _ = read_tmy3(DATA_DIR / '723170TYA.CSV', coerce_year=1990)
# fix TMY3 index to be monotonically increasing
greensboro = fix_tmy3_coerce_year_monotonicity(greensboro)
# get the rain data
greensboro_rain = greensboro.Lprecipdepth
# calculate soiling with no wash dates and cleaning threshold of 25-mm of rain
THRESHOLD = 25.0
soiling_no_wash = soiling_kimber(greensboro_rain, cleaning_threshold=THRESHOLD)
soiling_no_wash.name = 'soiling'
# daily rain totals
daily_rain = greensboro_rain.iloc[:-1].resample('D').sum()
plt.plot(
    daily_rain.index.to_pydatetime(), daily_rain.values/25.4,
    soiling_no_wash.index.to_pydatetime(), soiling_no_wash.values*100.0)
plt.hlines(
    THRESHOLD/25.4, xmin=datetime(1990, 1, 1), xmax=datetime(1990, 12, 31),
    linestyles='--')
plt.grid()
plt.title(
    f'Kimber Soiling Model, dashed line shows threshold ({THRESHOLD}[mm])')
plt.xlabel('timestamp')
plt.ylabel('soiling build-up fraction [%] and daily rainfall [inches]')
plt.legend(['daily rainfall [in]', 'soiling [%]'])
plt.tight_layout()

plt.show()