Load matching in residential buildings through the use of thermal energy storages

Vapour compression heat pump systems powered by photovoltaic panels represent the most diffused and cost-effective technical solution to provide heating, ventilation and air conditioning from renewable energy sources in the building sector. However, the aleatory distribution of daily solar radiation and its mismatch with heating, cooling and domestic hot water demand is the main constrain related to the exploitation of photovoltaic energy. Energy storage systems are fundamental to obtain high levels of energy self-consumption from non-programmable renewable energy sources, reducing the electricity exchange with the grid and the related operating costs. The aim of the study is to determine the optimal size of a water thermal storage to be coupled with photovoltaic panels and a vapour-compression heat pump, under energy end economic points of view. Two different kinds of building typologies are considered: a single-family and a multi-family house, characterized by different values of surface-to-volume ratios, internal occupancy and ventilation rates. Buildings energy modelling and dynamic simulations are performed through EnergyPLUS software. The size of the photovoltaic system is chosen according to the energy demand and different water thermal storages are simulated to find the optimal size for each building typology.