AbstractIn this paper the presence of customers (prosumers), connected to a District Heating Systems (DHS), that not only can consume but also produce district heating by means of small-scale solar collectors, and that can use the DHS as a virtual storage for the thermal energy produced and not immediately used, with the possibility to use it later, is investigated. Three configurations were simulated: (1) absence of solar thermal system, (2) solar thermal system not connected to the DHS, (3) solar thermal system feeding a local heat storage, connected to the DHS by a single bi-directional heat exchanger. The results show that for the connected configuration, the thermal solar system can overcome the limited production of the isolated configuration during summer, producing thermal energy to feed the DHS, and that the thermal energy produced annually is more than 100% the annual energy needs of the single family house for space heating and domestic heat water.