Experimental and theoretical study on a hybrid residential hot water system with solar and gas

• A hybrid residential hot water supplying system has been presented.
• The mathematical model of the system was established and its validity was tested.
• Economic analysis of the system was conducted under Shanghai weather condition.
• The impact of the minimum temperature rise of the gas water heater was analyzed.

This paper presents theoretical and experiment analysis of a hybrid residential hot water (HRHW) supplying system with domestic solar water heater (DSWH) and gas instantaneous water heater (GIWH) in shanghai. Mathematical model of the system has been established and its validity was tested by experiments. Economic analysis has been conducted for the HRHW system and traditional gas water heater systems through simulation along with Shanghai weather condition considering the influence of different minimum temperature rise (MTR) of GIWH. The economic comparison results show that the HRHW supplying system has greater economic benefits than gas water heater with a payback period of 7.2 years, and minimum temperature rise (MRT) of GIWH has low impacts on the supplementary gas consumption for the case in shanghai. For other region, operation of the HRHW system needs precise simulation according to the local meteorological conditions.