A new capacity design method for PV-ASHP system based on energy flow mechanism and energy supply-demand balance

Photovoltaic driven air source heat pump (PV-ASHP) system provides a solution for the simultaneous supply of electricity and heat for buildings in remote areas. However, due to the lack of simple and accurate capacity design methods for PV-ASHP system engineering, the capacity of various types of equipment is often inappropriate, which further reduces the performance and economy of the system. In this study, the respective energy flow and balance relationships of electricity and heat in the system are analyzed by establishing different energy network models of three typical operating conditions, and some new key capacity design principles are derived. Then, a new capacity design method based on energy flow mechanism and dynamic supply-demand balance in the PV-ASHP system is proposed, and the corresponding design process is given. Compared with the traditional design method, the maximum reduction rate of equipment capacity under the new design method is 68.0 %; the investment cost, operation cost and electricity abandonment rate decreased from 118,671.4 CNY, 16,880.9 CNY and 76.1 % to 83,459.0 CNY, 9611.5 CNY and 74.7 % respectively; meanwhile, the renewable energy fraction increased from 57.7 % to 65.1 %. The new design method provides a valuable reference for the accurate capacity design of PV-ASHP system engineering.