Biological growth

Definition

Biological growth develops where moisture and dirt collect, mostly along the lower frame edge of the panel. It differs from soiling in being a living layer that clings to the surface and grows by itself. Rain does not clean it off, and it spreads over time.

Signs in the imagery

In the RGB image it shows as green, grey or brown patches or bands along the frame edge. Because of its small, fine structure, detection requires RGB imagery at 1 cm per pixel or finer. If it has spread over the cells, the thermal image may show heating in the edge cells.

Possible causes

• A humid climate and surfaces that stay wet for long periods
• Water and dirt collecting at the lower edge because of low tilt
• Rows close to trees, water or shade
• Panels left uncleaned for a long time

Effect on production and safety

It permanently shades the edge cells and reduces production. The covered cells can heat up and become hot cells. It also causes moisture to remain around the frame and seals for long periods.

Recommended action

Clean the affected panels with a method that does not damage the glass or its coating. Do not use hard brushes or scrapers. On rows where growth concentrates, assess the source of moisture and shade and include those rows in the cleaning plan more often.