Here's a breakdown of the most common techniques: Using a hose and a soft-bristled brush to scrub the panels. Gentle on panels, effective for light dirt. Requires access to water, may need a ladder. No water needed. . Dust, dirt, pollen, bird droppings, and other debris can reduce energy output by 15–25%, according to the National Renewable Energy Laboratory. . Next, wash the panels with a soft cloth or sponge and a solution of water and mild soap or a specialized solar panel cleaner. Image courtesy of the researchers. A thin layer of dust can reduce your system's efficiency by up to 25%, turning your clean energy investment into an underperforming asset.
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