Development and Performance Assessment of a Solar-Powered Backpack Sprayer under Field Conditions

Abstract

The demand for sustainable and energy-efficient agricultural machinery has increased significantly due to rising fuel costs, labor shortages, and environmental concerns. This study focuses on the design, development, and performance evaluation of a solar-operated backpack sprayer suitable for smallholder farming systems. The sprayer was developed at the Workshop Machinery and Maintenance Division of Bangladesh Rice Research Institute (BRRI), Gazipur, incorporating a 15 W photovoltaic panel, a 12 V rechargeable battery, and a DC motor-driven pump. The system utilizes solar energy to operate the spraying mechanism, thereby reducing reliance on fossil fuels and manual effort while promoting environmentally friendly agricultural practices. The performance of the developed sprayer was evaluated through laboratory testing and field experiments under different operating conditions. Key performance parameters, including discharge rate, application rate, and field capacity, were measured and analyzed. The results indicated that the discharge rate remained relatively stable throughout the day, ranging from 1.49 to 1.55 L min ?1 , with an average value of 90.05 L h ?1 . The sprayer exhibited optimal performance during midday due to higher solar irradiance and battery voltage. The application rate increased from 20.83 to 104.16 L ha ?1 with increasing spray volume, while the field capacity decreased from 4.36 to 0.85 ha h ?1 , indicating a trade-off between application volume and operational efficiency. The effective field capacity and field efficiency of the backpack sprayer were recorded as 0.136 ha h ?1 and 71.39%, respectively. The study also revealed that solar irradiance and battery voltage significantly influenced system performance. Overall, the developed solar-operated sprayer demonstrated consistent performance, energy efficiency, and suitability for field conditions. The findings suggest that the system can serve as a viable, cost-effective, and sustainable alternative to conventional sprayers, particularly in rural and off-grid agricultural areas.