Techno-economic performance analysis and optimization of two household air source heat pump coupled systems

The air source heat pump (ASHP) with thermal energy storage is a promising solution for low-carbon building heating. This study simulates ASHP, valley-electricity thermal storage with ASHP (VEASHP), and solar-assisted ASHP (SAASHP) systems for a single-family residence in Shijiazhuang using TRNSYS, comparing techno-economic performance and identifying the optimal SAASHP configuration. The results indicate that the seasonal coefficient of performance for the VEASHP and SAASHP systems are 2.38 and 3.79, respectively. The SAASHP system offers more stable tank temperatures and higher efficiency, particularly during mid-season. Both systems offer significant benefits, with primary energy savings of 18 % and 47 %, and operational cost reductions of 21 % and 38 %, respectively. Compared to the wall-hung gas boiler system, the SAASHP system also achieves a 15 % reduction in carbon emissions, while the VEASHP system’s critical emission factor is 581 gCO₂/kWh. Accounting for projected 2035 energy price trends, SAASHP and VEASHP show 7.2 % and 3.5 % lower annual costs than ASHP, reflecting improved economic potential under future energy market conditions. The optimal tank volumes for VEASHP and SAASHP are 3 m³ and 4 m³, with the optimal collector slope and area being 50° and 50 m². Orthogonal analysis revealed that system performance is most sensitive to collector area and ASHP capacity, with the optimal SAASHP configuration comprising 45 m² area, 45° slope, 11 kW unit, and 4 m³ tank.