# pvlib.soiling.kimber¶

pvlib.soiling.kimber(rainfall, cleaning_threshold=6, soiling_loss_rate=0.0015, grace_period=14, max_soiling=0.3, manual_wash_dates=None, initial_soiling=0, rain_accum_period=24)[source]

Calculates fraction of energy lost due to soiling given rainfall data and daily loss rate using the Kimber model.

Kimber soiling model 1 assumes soiling builds up at a daily rate unless the daily rainfall is greater than a threshold. The model also assumes that if daily rainfall has exceeded the threshold within a grace period, then the ground is too damp to cause soiling build-up. The model also assumes there is a maximum soiling build-up. Scheduled manual washes and rain events are assumed to reset soiling to zero.

Parameters
• rainfall (pandas.Series) – Accumulated rainfall at the end of each time period. [mm]

• cleaning_threshold (float, default 6) – Amount of daily rainfall required to clean the panels. [mm]

• soiling_loss_rate (float, default 0.0015) – Fraction of energy lost due to one day of soiling. [unitless]

• grace_period (int, default 14) – Number of days after a rainfall event when it’s assumed the ground is damp, and so it’s assumed there is no soiling. [days]

• max_soiling (float, default 0.3) – Maximum fraction of energy lost due to soiling. Soiling will build up until this value. [unitless]

• manual_wash_dates (sequence or None, default None) – List or tuple of dates as Python datetime.date when the panels were washed manually. Note there is no grace period after a manual wash, so soiling begins to build up immediately.

• initial_soiling (float, default 0) – Initial fraction of energy lost due to soiling at time zero in the rainfall series input. [unitless]

• rain_accum_period (int, default 24) – Period for accumulating rainfall to check against cleaning_threshold. The Kimber model defines this period as one day. [hours]

Returns

pandas.Series – fraction of energy lost due to soiling, has same intervals as input

Notes

The soiling loss rate depends on both the geographical region and the soiling environment type. Rates measured by Kimber 1 are summarized in the following table:

Region/Environment

Rural

Suburban

Urban/Highway/Airport

Central Valley

0.0011

0.0019

0.0020

Northern CA

0.0011

0.0010

0.0016

Southern CA

0

0.0016

0.0019

Desert

0.0030

0.0030

0.0030