Soiling and optical losses are two major challenges in photovoltaic (PV) systems that lead to reduced energy output over time. Anti-soiling coatings (ASCs) help reduce dust accumulation, while anti-reflective coatings (ARCs) improve light transmission, both playing key roles in enhancing long-term PV performance. In Indian conditions, soiling is a major problem which can cause significant loss of power. While frequent cleaning is always a solution, the development of suitable ASCs can be very beneficial. To evaluate the durability and effectiveness of these coatings under different environmental stressors, a set of indoor accelerated test setups has been developed at NCPRE at IIT Bombay. The abrasion test bed (Cleaning Cycle Simulator – CCS) shown below, replicates a full day of environmental exposure through five programmable stages: (1) cooling at 21 °C (adjustable to 15 °C) for night-time simulation, (2) dew formation for early morning moisture, (3) soiling, where dust is applied uniformly using high-pressure N₂ gas from a 20 cm height and 2 cm nozzle gap inside a sealed acrylic chamber, (4) heating at 65 °C (adjustable up to 75 °C) for afternoon thermal stress, and (5) cleaning using a brush, configured for both dry and wet cleaning, to simulate real-world cleaning actions.

The CCS complies with the requirements of the international IEC 62788-7-3 standard, which NCPRE helped develop, and is designed for small glass coupons up to 18 cm×18 cm, enabling controlled and repeatable testing. A rainfall simulator is also available, producing 2 mm droplets from 3 m height at 7.3 m/s with 21 mm/h intensity, parameters selected based on real rainfall data, for studying the mechanical and chemical effects of rain, with adjustable water pH. For photodegradation studies, we have the capability to expose coatings to UV radiation intensities up to 340 W/m² under controlled temperature conditions, including setups for both dry UV and combined UV + condensation cycles. These facilities enable multi-stressor, accelerated testing of ASCs and ARCs under controlled indoor conditions. These test facilities have been extensively used for the performance evaluation of coatings from various manufacturers as part of our ongoing research at IIT Bombay. In addition to in-house studies, we have provided coating evaluation studies to several coating developers, PV plant installers, and module manufacturers. We have also actively participated in multiple round-robin and collaborative international studies involving leading institutions such as NREL, Fraunhofer CSP, and universities like UNSW, Loughborough, and others. The research is conducted by several NCPRE students under the supervision of Prof. Anil Kottantharayil and Prof. Narendra Shiradkar.