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‘Dirty’ vs ‘Persistent’ : Understanding the Types of Soiling Environments
Optimized cleaning schedules are dictated by the complexities of a site’s soiling environment
Solar panel soiling is not a uniform challenge; it varies significantly based on environmental conditions. Solar Unsoiled has identified two primary types of soiling environments, each requiring a unique approach for effective management.
Solar panel caked with ‘dirty’ style soiling.
‘Dirty’ Soiling Environments ‘Dirty’ environments involve the visually-apparent form of soiling that typically comes to mind when imagining a dusty set of solar panels. The layers of debris that accumulate during prolonged dry seasons are so prominent that one can swipe their finger across the panel and see the noticeable trail. The buildup of soiling that makes these panels less efficient is counteracted by a natural, albeit partial, remedy. During the rainy season, showers act as a natural cleaning agent, washing away a substantial portion of the soiling.
The soiling profile in ‘dirty’ environments thus resembles a sawtooth – extreme losses during the dry seasons and sharp recoveries during the months with rain events. Southern California is a prime regional example of a ‘dirty’ soiling environment.
Black, film-like ‘persistent’ style soiling at a farm that experienced an incomplete cleaning. More advanced cleaning methods are required to fully recover site performance.
‘Persistent’ Soiling Environments Conversely, the ‘persistent’ soiling environments are best described as having sneaky soiling. Though still technically dirty, this type of debris accumulation is not apparent to the human eye and swiping one’s finger across the panel doesn’t seem to do a thing. Over years, soiling builds up on the panels and is practically independent of rainfall events. Instead of cleaning the panels, rain catalyzes physical and chemical reactions on the panel surfaces that leads to cementation – particles becoming even more tightly adhered.
A black film of microscopic organic material that makes the panels less efficient compounds over time, leading to a soiling profile that increases with each passing year. Solar sites all across the Southeast US show evidence of a ‘persistent’ soiling environment.
‘Dirty’ soiling profiles are characterized by extreme buildup and sharp drops due to partial cleanings by rain. Optimized cleanings are highly seasonal.
Approaching Optimized Cleanings The disparities in soiling environments translate into the way soiling mitigation is optimized. ‘Dirty’ environments need an answer to the question: how frequently to clean? Leaning more heavily on seasonally-sensitive data analytics methods, Solar Unsoiled provides sites in these types of environments with highly-seasonal optimized schedules that involve manual cleanings during the dry periods.
‘Persistent’ soiling profiles build up over time despite rainfall events.
‘Persistent’ environments instead ask the broader question: when to clean? Leaning more heavily on quarterly microscopy imaging of solar panels, Solar Unsoiled monitors and predicts the years-long buildup of soiling and provides optimized cleaning schedules based on a site’s economics and its unique ‘persistent’ profile.
Overall, detailed analysis and tailored strategies for each type of soiling environment is crucial to maximizing profit at each site across a fleet.