Simulation and measurement for carbon reduction characteristics of photovoltaic,solar thermal,and air-source heat pump hot water systems

Domestic hot water heating quality and usage are improving in China,with energy consumption playing a prominent role in building energy conservation development.Various models have been established and tested jointly with national testing centers to compare the carbon reduction performance of solar thermal,photovoltaic,and air-source heat pump (ASHP) hot water systems.The correlation between the carbon reduction characteristics of the systems and the outdoor temperature,radiation and operating control strategies has been analysed.The results indicate that the low temperature in severe cold zone and cold zone significantly affects the solar thermal insulation and ASHP evaporation conditions,and the carbon reduction contribution of the solar thermal system is greater in Class II solar resource areas.The performance of ASHP is optimal in mainly hot summer zones,however the utilization and stability of the solar thermal system are not superior as the photovoltaic system in Class II and III solar resource areas,affected by the normalized temperature difference.The photovoltaic system is constrained by the module efficiency,resulted in the lower energy utilization efficiency than the solar thermal system,but will achieve a significant improvement by increasing photovoltaic installation capacity.