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Distributed solar heating systems have high energy-saving potential as clean and energy-efficient production units in residential building applications. Solar energy resources are weak in hot summer and cold winter zone in China, which makes it difficult to completely rely on solar energy to heat residential buildings. A critical challenge is the lack of a theoretical basis for how to choose the solar-assisted heating system form. In this paper, seven solar-assisted heating systems are modeled and their performances are evaluated in six cities by using TRNSYS software. In terms of performance indicators, the solar fraction, the season performance factor, and the heat efficiency are used to thoroughly discuss the viability of using solar heating technologies in this zone. Based on the results, the average indoor air temperature was maintained between 16 °C and 20 °C, and the lowest solar fraction obtained was 10.1%. The carbon emission reduction in each city ranged from 60 kg to 400 kg, yielding good environmental benefits. According to the comprehensive comparison of the six evaluation indexes considered, the parallel or dual-source solar-assisted air source heat pump system can be used in a zone with medium solar energy resources. It is more suitable to use a dual-source solar-assisted air-source heat pump system in a zone with poor solar energy resources. The findings of this work can guide and promote the widespread application of distributed solar heating in household residential buildings in the hot summer and cold winter zone in China. [Display omitted] • The application status of solar heating technology is investigated in HSCW zone. • TRNSYS simulation verifies the feasibility of 7 different solar-assisted systems. • Comprehensively evaluate the thermal performance of 7 systems in 6 cities. • Multi-dimensional investigations of which system is suitable in HSCW zone. [ABSTRACT FROM AUTHOR]

Abstract The paper presents the annual results of monitoring a hybrid heat source consisting of a condensing gas boiler, ground and air heat pump, and solar collectors. A boiler with a nominal heat output of 186 kW works with an 81.1 kW ground-source heat pump, a 27.4 kW air-to-water heat pump and six solar collectors. The hybrid heat source is located in the fire brigade building to provide heat for space heating and ventilation and to supply domestic hot water. The annual monitoring results of the hybrid heat source were analysed in detail. The entire heat plant was equipped with measuring instruments enabling determination of heat output of individual devices, average boiler efficiency in the heating and summer season, the heating seasonal performance factor for ground and air heat pump, gas consumption by the boiler and electricity consumption by individual devices. The heat energy produced by individual devices was determined for a given period. Selected results of the economic analysis are also discussed. The annual costs of purchasing gas and electricity consumed by heat pumps were compared. Boiler efficiency as a function of parameters characteristic for a hybrid heat source was presented. The use of ground and air-source heat pumps and solar collectors reduced the consumption of natural gas during the year by 21,621 m3. As a consequence of the reduced natural gas consumption, the carbon dioxide emissions decreased during the year by 13.32 Mg. Highlights • A system of a gas boiler, solar collectors, ground and air heat pumps was studied. • One year operation of a hybrid heat source system was experimentally assessed. • The efficiency of a boiler was 0.96 in the heating season and only 0.6 in summer. • The share of the ground heat pump in annual heat production was 43% and boiler 51%. • Significant reduction in the gas consumption and CO 2 emission was achieved. [ABSTRACT FROM AUTHOR]