Design and construction of a solar powered grass cutter for small residential lawns

Abstract

The increasing environmental concerns and the need for sustainable alternatives in lawn care equipment have prompted the exploration of innovative solutions in a bid to fulfill SDG-7, which aims to ensure modern energy for all. The traditional gasoline and electric powered grass cutters fall short in addressing concerns such as air and noise pollution, fossil fuel dependency and limitation of use to areas connected to the grid. It is in this context that the innovative concept of solar powered grass cutters emerges as a compelling solution. This report explores the steps that were followed to design and construct a grass cutter that exploits Uganda’s abundant solar potential with an average of 5 to 7 Peak Sunshine Hours daily(Mugagga et al.,2019). Through field observations, document reviews, and interviews with lawn care professionals, key design requirements identified included ergonomics, safety features, operational efficiency, and minimal noise production. The chosen design concept was one that aims to avoid damage to the solar cells that is to say, the solar panel is only used to charge the battery prior to operation, but it is not mounted onto the machine. The designed solar powered grass cutter comprised a 12 V DC 800 W motor, a Lead acid battery (12V, 80 Ah), Solar Panel (100W), rotational blade (2mm thick, High Carbon Steel) and a control switch. The entire operation frame work is achieved using the electric motor which is able to provide the necessary torque (2.1 Nm) needed for the rotation of the blade which is mounted onto the motor shaft. The machine is operated by a switch on the board which closes the circuit and allows current flow to the motor and ultimately causes the actuation of the cutting blade. Sequentially, the prototype was tested on paspalum compound for battery discharge time and field efficiency across various grass heights and weather condition (rainy and sunny conditions. Results indicated 70% field efficiency and the best operation noted on short grass in dry condition with an average battery discharge time of 51 minutes. However, when dealing with taller wetter grass, the average battery discharge time stood at only 38 minutes due to a greater power consumption requirement. Conclusively, the project demonstrates the potential of solar-powered technology in revolutionizing residential lawn care as it provides a viable and environmentally friendly alternative to traditional models, exhibiting reduced noise and zero emissions.