Exploring the Performance of a PV-Supplied Cooking System with Hybrid Electric-Thermal Energy Storage

Abstract

This research explores the extent to which the addition of a thermal storage tank can reduce the electrical cooking energy in solar Photo-Voltaic (PV) supplied cooking systems. The aim is to consider a smaller battery size to store the decreased electrical cooking energy and the rest of the solar energy is stored in a low-cost thermal storage tank. This is done to reduce the cost of the storage unit to address the challenges of clean-cooking access in rural African households without grid electricity. The energy performance of the system is evaluated considering a small-scale solar system that powers a storage water heater as the thermal storage tank and a slow cooker as the cooking appliance. A thermal-electrical analogy and experimental tests are employed to model and validate the effectiveness of the system under different cooking conditions. Rice is chosen as the cooking medium because it is the fastest growing staple in Africa, and its cooking process benefits from starting it with pre-heated water. It is shown that starting with pre-heated water accelerates the readiness of rice, and reduces the additional electrical energy to complete the cooking process which translates to a similar battery size reduction. The results from three cooking scenarios indicate that a hybrid cooking system incorporating a battery and thermal storage tank can reduce the battery capacity requirements by up to 24.3% for one meal, 14.7% for two meals, and 10.6% for three meals in comparison to a pure electrical cooking system with a battery only.