Cost optimal sizing of photovoltaic-battery system and air–water heat pump in the Mediterranean area

Heat pumps combined with photovoltaic (PV) system with batteries will allow environments to be heated/cooled sustainably. The framework of this paper is a household with a boiler in which the user intends to purchase a PV-battery system and an air–water heat pump (AWHP). A procedure is defined to carry out the combined sizing of the three components in order to minimize the net present costs over 20 years of operation. The required input data are obtained from energy simulations carried out in EnergyPlus. These are processed by a calculation code in which the components and the management system are modelled according to the standards. The parametric analysis, carried out by varying the sizes, allows the optimal solution to be obtained for 5 Italian locations with different climatic characteristics. The results show that the size of the PV plant is independent of the availability of the solar source, but it strongly depends on the building thermal demands. The battery size, on the other hand, depends on both climatic characteristics and PV size. The initial cost sensitivity analysis shows the strong interdependence between AWHP and PV plant sizes and between PV plant and battery sizes, demonstrating that combined sizing is necessary.