Cost Optimization of Hybrid Solar/ Heat Pump Water Heating System : Model Formulation

Domestic water heating is becoming more recognized as a significant source of energy consumption in buildings. The pervasive use of non-renewable fossil-based water heating technologies comes at a high cost and significantly contributes to the climate crisis. Thus, the Nigerian energy situation necessitates the prompt adoption of sustainable energy systems and the efficient application of hybrid in order to achieve net-zero energy in buildings. This paper presents a mathematical model of a hybrid solar/heat pump water heating system. The proposed system consists of solar thermal collector, storage tank, heat pump, and grid system. The proposed model aims to reduce grid energy costs by optimizing the switching control of the heat pump water heater. Control variable is the heat pump water heater switch. The mathematical model is based on energy balance equations, and the optimization problem is a mixed integer nonlinear. The economic benefits of this hybrid technology in terms of cost savings and energy reduction are promising. The proposed model can save about 56% of energy consumption and N192.08/day of cost savings is achievable with the hybrid system. Adoption of this hybrid technology has the potential to significantly reduce energy consumption while compensating for energy shortages in the majority of African countries.