Factors Influencing the Abrasion Damage to Antisoiling Coatings on Photovoltaic Modules

Abstract

Soiling significantly reduces the performance of PV modules, and robotic cleaning is commonly used to mitigate dust in large PV plants. However, frequent cleaning can damage antireflective/antisoiling coatings. This paper examines factors affecting abrasion damage on four commercial hydrophobic coatings (A, B, C and D) using a cleaning cycles simulator that emulates real-world conditions. Key findings include: (1) the presence of dust/soil during cleaning cycles decreases the coating life by 82×, compared to only-clean cycles, thus acting as the most significant stressor that abrades the coated samples. (2) Cleaning the samples with a brush material that has higher hardness (1.3×), coated samples show 3× lesser coating life. (3) Microfibre cloth brush causes the least damage to the antisoiling coatings (compared to other brush materials), as it applies the smallest weight on the sample's surface. (4) Coated samples show reduced (3×) coating life when cleaned with the direction of brush rotation as ‘towards the direction of travel,’ compared to ‘opposite to the direction of travel’ and ‘clockwise rotation.’ When the brush rotates towards the direction of travel, greater abrasion damage is seen due to the combined effect of dust particles (being dragged along with the brush) and brush bristles. (5) Reducing the horizontal velocity of brush travel by four times from 0.4 to 0.1 m/s results in a 3× decrease in coating life. PV developers and robotic cleaning manufacturers should optimize these variables to minimize damage to the top coatings applied on PV modules.