Mold, mildew, and biological films such as lichen can act as a living anchor that traps dirt, dust, and pollen directly on the glass. When left untreated, biological buildup can block light from reaching photovoltaic cells, create uneven shading across modules, accelerate re-soiling, and may contribute to long-term coating degradation. Professional cleaning removes this buildup before it compounds into a larger performance or maintenance issue.