Renewable energy source such as solar energy is available abundantly, therefore, by utilizing solar energy using solar panels a sprayer can be powered. In order to cover a large area and to overcome the scarcity of labour, the bullock-drawn, solarpowered, high-clearance sprayer was developed to utilize the available solar energy. The sprayer also can be used for spraying huge field crops due to its high clearance. The solar energy was used as the power source for the operation of sprayer unit while bullock power was used for pulling the cart. Significantly, solar energy is abundantly available throughout the year and in order to save fossil fuels, such as diesel and petrol, solar energy is one of the most promising solutions and, therefore, needs to be utilized for spraying operation. The practical utility of solar-powered, bullockdrawn sprayer has a wide scope in the country. The development and popularization of solar-powered, bullock-drawn, high-clearance sprayer for cotton and red gram crops is essential and has a wide scope in Karnataka. The entrepreneurship among farmers/users can also be created by conducting frontline demonstrations in farmers’ fields. The revenue generation can also be done by the adoption of custom hiring service centre in villages. Hence, solar-powered, bullock-drawn, high clearance has more scope in India.

Constructional Details and Specifications

The sprayer basically consists of the working components discussed below.

Components of SolarPowered, BullockDrawn, High-Clearance Sprayer

The sprayer consists of the working components, such as solar photovoltaic (PV) modules, spray tank, DC motor pump, battery, wheel, seat, spray boom, nozzle, and pressure control device. The individual components were procured, fabricated, assembled, and developed in the College of Agricultural Engineering, Raichur.

Selection of Solar PV Modules

The solar PV modules were selected based on the power requirement of the motor and the pump. The discharge rate and the operating pressure influence the selection of the solar PV modules. The main parameter which influences the solar PV module is the temperature of the region and maximum sunshine hours. According to the requirement the capacity of solar PV modules selected was 500 W. The specifications of a single PV module is presented in Table 1.

Selection of Motor

The selection of DC motor involves the discharge rate and the operating pressure required for the sprayer. The actual power required to pump the liquid and the power available from the solar PV modules should be matched with the motor. The DC motor is getting power from the PV modules directly and is coupled with the pump. The platform is made for both the pump and motor for uniform rotation of shafts. The specifications of the selected motor is presented in Table 2.

Selection of Pump

The gear pump was selected based on the power requirement for operating the sprayer. The selected gear pump is coupled with DC motor to pump the liquid. The speed of both the pump and motor should match with each other. The pumps used are of two sizes, namely, 25 L/m and 50 L/ min. The pump was connected to a tank through the suction pipe. The specification of the selected rotary pump is presented in Table 3.

Suction Pipe

The suction pipe is used to suck the liquid from the tank with the help of X nipple. The 19.05 mm and 25.4 mm flexible plastic pipe of 25 cm was selected to deliver the liquid.

Delivery Pipe

The delivery pipe was selected according to discharge and capacity to withstand the pressure. The flexible hose pipe was selected to deliver the water to spray boom. Tee joint with two sizes of 19.05 mm and 25.4 mm ball valves (flow control valves) were provided in the delivery pipe for diverting the flow. One of the ball valve remains closed during the operation.

Battery

The batteries used here are lead acid dry type. Two batteries of 12 V capacities were used. The PV modules produce 72 V as each panel will produce 36 V. The batteries were kept besides the tank. The current from the PV modules is continuously stored into the batteries in the sunshine hours. The switchboard is provided for batteries and PV modules. The batteries give constant power to the motor due to stored electricity. The PV modules give intermittent power to the motor because of variation in the solar intensity. Because of the higher voltage, the capacity of the PV modules is limited to 500 W. The specifications of the battery is presented in Table 4.

The solid diagram and line diagram, front view, side view, and top view of bullock-drawn, solar-powered, high-clearance sprayer is presented in Figures 1, 2, and 3, respectively.

Fabrication of Sprayer

A solar-powered spraying system has been developed for field crops. The spraying system consists of five hollow cone nozzles having discharge of 25 L/min and 50 L/min. The sprayer is provided with 500 W solar panels; five nozzles are provided for spraying five plant rows. The solar sprayer is provided with DC pump of 0.5 hp and the operating pressure of the pump is 10 kg/cm2. The pump is coupled with 24 V DC motor having an rpm of 1,500. The sprayer is provided with a water tank of 275 L capacity.

The two solar panels of 250 W are mounted on the frame through nut and bolt system. The frame is made up of mild steel angles. The length of the frame is 1.70 m; width of the frame is 2 m. This frame has 5.08 cm angled mild steel and mild steel flats for supporting the base of the panels. The frame is supported by a four-angled steel from the tank platform. The length of the angles is 92 cm and the size is 2.54 cm. The base of the frame and supporting angles are welded for rigid structure. The pump capacity is designed on the basis of discharge rate and operating pressure. The panel capacity was decided based on the pump capacity requirement. The seat of the operator is placed at the front end of the panels. The specifications of bullock-drawn, solar-powered, high-clearance sprayer is presented in Table 5.

Components of Sprayer

• Solar PV modules
• Spray tank
• DC motor
• Pump
• Battery
• Wheel
• Seat
• Spray boom

Economics of BullockDrawn, Solar-Powered, High-Clearance Sprayer for Selected Field Crops

The cost of operation and the savings are presented in Table 6.

The economics of the bullock-drawn, solar-powered, high-clearance sprayer were calculated. It was observed that, the cost of operation of this sprayer was `121.1/h and it was `128.14/ha for cotton and `119.66/ha for redgram crop. Breakeven point and payback period were 123.61 h/annum and 3.6 years. Per cent of financial saving over the manual knapsack sprayer was 56 per cent for cotton and 67.1 per cent for redgram crop. Per cent of labour saving over the manual knapsack sprayer was 56.6 per cent in cotton and 59.48 per cent in redgram crop.

In order to create awareness among the users, training programmes and demonstrations were conducted for the farmers, commercial manufacturers, village artisans, and the other users. For fabrication, sale, and service of bullock-drawn, engine-operated sprayer for the farming community, the commercial manufacturers in this region have been identified for further popularization. The safety aspects to be followed for the sprayer have been educated by conducting frontline demonstrations in villages.

Dr M Veerangouda, Principal Investigator; Dr K V Prakash, Asst Agril. Engineer; Dr Jagjiwanram, Animal Scientist; and Dr M Din, Project Coordinator, All India Coordinated Research Project on Increased Utilization of Animal Energy with Enhanced System, College of Agricultural Engineering, Raichur, Karnataka, India.