Real-world performance and module degradation impacts of robotic cleaning in PV systems

Robotic cleaning is increasingly adopted worldwide to mitigate soiling losses in utility-scale photovoltaic (PV) systems. However, long-duration, side-by-side field evaluations of different robotic cleaning technologies under real field conditions remain scarce. This study presents the first comprehensive comparative assessment of multiple cleaning robots operating under identical field conditions in a dry and dusty desert environment. In addition to extensive outdoor and indoor experiments, a key methodological contribution of this work is the development of an irradiance-independent, short-circuit current ( Isc ) – based protocol for robust benchmarking of cleaning efficiency in outdoor environments. At the system level, the analysis considers the combined effects of robot design, module type (monofacial and bifacial), and cleaning frequency (daily, weekly, and no cleaning) to evaluate cleaning efficiency, operational reliability, electrical performance ( Pmax ), electroluminescence (EL) response, anti-reflective coating (ARC) characteristics, and module vibrations during cleaning. Results show that all robots achieved high cleaning efficiency with cleanliness restored to >99% under daily cleaning schedules, whereas extended intervals lead to residual soiling (cleanliness reduced to