Performance of solar cooker with evacuated tubes and photovoltaic panels with phase change materials

Solar cooker has its own significance with an impact of substituting conventional source of energy for cooking. Solar cookers with electrical backup have proven the usage in off-sunshine hours to some extent. A cheaper and competitive PV and evacuated tube–based solar cooker with a control unit with incorporation of phase change material for energy storage were utilized without any interruption during off-sunshine hours for effective cooking. The proposed system has a control circuit connecting solar PV, DC output storage device (Battery 12V 75 AH), and DC-linked Nichrome heating coil. Three phase change materials, viz., palm oil, coconut oil, and paraffin wax, have been used in the system to extract and use the energy stored during sunshine hours in the materials. Figure of merit (F₁) and figure of merit (F₂) values for the system with the phase change materials have been found by doing experiments to find stagnation temperature without load and with load. The values of F₁ (0.139) and F₂ (0.42) for coconut oil are found to be effective with an energy efficiency of 38% compared to the other materials in the study with electrical backup.