A cost-optimal solar thermal system for apartment buildings with district heating in a cold climate

Finding the global optimal combination of the main components for a solar thermal energy system is an important topic in utilising solar radiation in a cost-effective way. However, selecting an optimal solar thermal system in a cold climate condition is a challenging task due to the dependency on the heat demand and the limited availability of solar radiation. This research presents several sets of optimum combinations of a solar thermal collector and a hot water storage tank regarding energy efficiency and the life cycle cost. Since domestic hot water consumption forms the significant part of the heat demand in new energy efficient apartment buildings, the applied consumption information were extracted precisely according to measured data. The solar thermal system with cost-optimal component sizes was able to save district heat energy consumption up 24% to 34% and made 4 €/m^2 to 23 €/m^2 in financial profit.Peer reviewe