Photovoltaics for cocoa pod splitting

Scientists have designed a cocoa pod splitting device that runs on five monocrystalline PV panels. They have simulated its operation and have found it can achieve a splitting efficiency of 98.92%.

A research team from Ghana has designed and analyzed a PV-powered cocoa pod splitting machine.

“Cocoa pod splitting is executed manually in less developed regions using hand tools such as machetes, a method that is time-consuming, labor-intensive, and serves as a hazard to workers,” explained the team. “With the development of mechanical solutions to address these limitations, their adoption has been challenged. This is mainly due to high operating costs, limited access to electricity, and dependence on fossil energy sources, especially in rural off-grid cocoa-growing areas.”

The proposed system was first simulated using MATLAB/Simulink and later validated with an experimental setup. In addition to PV panels, the design also included a hybrid GEL battery bank, a charge controller, and a DC motor.

The mechanical cocoa pod splitting machine was assumed to consume 4,720.463 Wh/day. It was simulated to run on five monocrystalline PV panels of 275 W each. They were connected in a parallel string, reaching a total array capacity of 1,375 W.  Based on data from the Ghana Meteorological Agency (GMA), the average solar irradiation was set to kWh/m2 per day with a minimum and maximum temperature of 24 C and 41.6 C, respectively.

The battery component includes ten hybrid GEL batteries of 100Ah each, with 80% depth of discharge, resulting in a capacity of 867.732 Ah. Two batteries in series are sufficient to provide adequate voltage to operate the prime mover, while the remaining four pairs of series-connected batteries were connected in parallel. The charge controller is set up on 24 V, while the DC motor has 1.3 hp. The experimental setup included mainly the same components and was installed in Kumasi, central Ghana. The PV array was installed with a tilt of 15°.

“The system demonstrated consistent energy supply to the machine, with sufficient autonomy for three operating days, whilst producing 5,843.75 Wh/day, which surpasses the 4,720.46 Wh/day energy requirement of the machine by 23.7%,” the results showed. “Real-world performance aligned closely with simulation predictions, confirming the PV system’s viability.”

The academics also found that the experimental setup had a splitting efficiency of 98.92%, and a separation efficiency of 91%-96.5%. The bean damage was found to be 1.03% with a 60 cocoa pods/minute throughput. “The integration of renewable energy improves sustainability, minimizes reliance on fossil fuel, and contributes to achieving SDG 7, 9, and 13 in postharvest agricultural mechanization,” they concluded.

The details of the system can be found in “Design and Integration of a Solar Photovoltaic System for Mechanized and Sustainable Cocoa Pod Splitting,” published in Solar Compass. Researchers from Ghana’s University of Mines and Technology and the Kwame Nkrumah University of Science and Technology conducted the study.