Paper Conference

Proceedings of BSA Conference 2019: Fourth Conference of IBPSA-Italy


Control strategies to increase the photovoltaic self-consumption of air-source heat pump systems

Maria Pinamonti, Alessandro Prada, Paolo Baggio

Abstract: Decreasing the use of fossil fuels for heating and cooling applications in buildings is one of the main concerns in reaching the energy reduction targets defined by the European Union countries. For this purpose, high efficiency heating and cooling systems are required, together with appropriate control strategies. The use of heat pumps (HP) in residential buildings is spreading, and the combination of these systems with the on-site production of photovoltaic (PV) energy can lead to high levels of renewable energy self-consumption. However, a poor design and a lack of control in the system can lead to a large amount of PV energy surplus, which has to be sold to the grid, or wasted. For this purpose, the use of energy storage and demandside management strategies are crucial. This paper describes a control strategy for an air-source HP system combined with a PV plant for a residential building. The control strategy aims to maximize the self-consumption of PV power, varying the system behavior depending on the instantaneous PV production. When an overproduction of PV energy occurs, the HP operates to store the surplus of solar energy by exploiting the storage capacity and the building thermal capacitance. In this study, the heat pump was controlled by acting on the compressor rotational speed (i.e. the frequency of the supplied power). The compressor was controlled in order to operate at the maximum capacity level compatible with the power supplied by PV. The effectiveness of the control strategy was assessed over a whole year, considering both the heating and cooling season and domestic hot water (DHW) preparation. The simulations were performed using the TRNSYS simulation software, considering a double-story residential building in northern Italy. The results obtained with the proposed demand side management (DSM) strategy show a reduction of around 33% of the energy taken from the grid with respect to a similar system with a standard control strategy.
Pages: 259 - 266