Feasibility study of a smart building energy system comprising solar PV/T panels and a heat storage unit

In this study, a novel design of ‘smart building energy systems’ is proposed. In the proposed system, solar photovoltaic-thermal (PVT) panels are integrated with a heat storage tank to supply a significant portion of the building’s heat and electricity demands. The system does not have any battery making it considerably cheaper and may have a two-way interaction with both of the local heat and electricity grids. In this way, the proposed system is strongly compatible with countries with both electricity and heat grids, e.g., Denmark. By such a system, not only the share of renewable energy in the national energy matrix may securely increase, but also the building will benefit the cheap, environmentally-friendly energy flows produced by its own. Considering the local weather data of a real smart building located in Western Denmark, the proposed building energy system is investigated. The results reveal that the system not only provides the entire annual domestic hot water building but also it generates 402.8 m3 hot water of 40 °C to be sold to the local ultralow-temperature district heating grid. With 2083 kWh electricity bought from the grid vs. 1938 kWh sold to that, the building’s yearly electricity cost is almost compensated.