The soiling on PV panels can be induced by the presence of dust, air pollution, sand, salt, bird droppings, snow etc.

The impact on the production is commonly assessed during the initial Energy Yield Assessment (EYA). It is usually assumed that the soiling losses are estimated to be at least 1% per year (linear) for a typical plant design (tilt angle of the panels between 15° to 25°) and a “standard” location (country or city).

For specific location, it is highly recommended to evaluate the potential losses with more precision in terms of seasonality (non-linear losses), location and environmental specificities (sandstorms in deserts, bird droppings close to the sea..). The losses are heightened if the tilt angle of the panels are low (below 10°).  

This impact on losses must be followed during Operation as well:
(i) to ensure the performance of the plant
(ii) to adjust the soiling losses value
(iii) thus, to evaluate if a module cleaning is necessary.
It will allow the adjustment of OPEX in the Business plan by adding or removing cleaning modules interventions.

By David Roisse, Asset Manager