Study on Solar and Heat Pump Combined Domestic Water Heating Systems with Diurnal Storage

In the paper, a simple domestic water heating system is assumed and a solar and heat pump combined heating system with diurnal storage is designed for it. Hourly simulations during a whole year were conducted under various conditions, such as different solar collector area, storage volume and heating capacities of heat pump, different hot water consumption profiles and so on. Based on the results of various simulations, some conclusions were drawn, such as the total energy-saving fraction, the water temperature variation, the suitable match of collector area, heat pump capacity and storage volume.