Study finds rainfall inadequate for cleaning solar panels, leading to significant energy production losses from tree pollen.

A study by experts from the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL), Duke University, Solar Unsoiled Inc., the University of Jaén in Spain, and Sapienza University of Rome has found that rainfall is insufficient to effectively remove tree pollen from solar panels. The researchers found that pollen from tree species such as cypress, juniper, pine, and oak proved particularly resistant to adhering to solar panels during peak pollen seasons. Despite these ‘cleanings’, unwashed panels suffered approximately 10% annual production loss. Manual cleaning with a wet brush after rain increased performance by 5% to 11%. The researchers noted that pollen particles from different trees have varying adhesion levels, influenced by factors such as the size and shape of the grains, their compositional properties, and environmental conditions like relative humidity and wind patterns.