With such a groundswell of solar growth, what can limit the performance of PV systems?
The answer is dust, or other forms of soiling that accumulate on the glass surface of solar panels, obscuring light from the cells within.
Driven by location and weather, soiling is worst in deserts, in the presence of air pollution, and on solar arrays that have flat tilt designs.
Moderate soiling that results when panels are not cleaned monthly is generally calculated to result in a 30% energy yield loss per year, while longer term, cumulative soiling cementation of dust materials can result in a 100% loss of yield.
Understanding soiling is a first step, knowing how to clean is a second step, but knowing when to clean is still the elusive element in the soiling control chain.
One tool for determining the cost-effectiveness of panel cleaning that Kipp & Zonen company offers is its DustIQ monitoring system.
The technology employs Optical Soiling Measurement (OSM) to determine the amount of soiling, including a LED and a photodiode to measure the light scattered by dust and other soiling materials on the top of the solar panel glass.
DustIQ also contains a PV cell, which allows users to calibrate the unit for local dust characteristics, which can vary greatly in particle size and color, to help predict soiling.
With the knowledge that energy yield of a PV system is down 5%, 10%, or more, owners can opt to clean panels in a system at the most cost effective time, setting their own trigger-point for when to act.
With close to 100 gigawatts of new solar installed in the world every year now, solar system maintenance has also become a huge industry by itself.
This, in turn, has also given rise to a preventative demand for special coatings for solar panel glass that can shed soiling.
Reference- Clean Technica, Kipp & Zonen website, US National Renewable Energy Laboratory Report