Air-to-water heat pump optimization with a photovoltaic system

Abstract: Photovoltaic systems and heat pumps installations are increasing faster than ever before in Finland. Load regulation is becoming a hot topic in the PV market. With load regulation, the self-consumption can be increased, and the user may earn money. An air-to-water heat pump can be regulated with own produced electricity from a PV system by overheating the tank. A typical single-family house of 150 m2 is simulated in Polysun for one year. The house has a photovoltaic system of 5.76 kW and an air-to-water heat pump with a tank of 180 l. The heat pump is used for space heating and domestic hot water. It is located in Helsinki, Finland. This work aims to compare two different control strategies for the heat pump.The first control strategy is based on the power output from the photovoltaic system and the second control strategy also takes the electricity consumption of the house into account. Both control strategies overcharge the tank with the heat pump to its maximum temperature of 65°C. Key figures such as self-consumption of photovoltaic system, annual electricity savings, payback time of regulation components and the performance of the heat pump are evaluated. The investment of a control system for overcharging is economically feasible, and the selfconsumption of the photovoltaic system has been increased due to overcharging.Economical savings has been made annually and mostly during Summer. The performance of the heat pump has decreased slightly with overcharging.