Solar thermal prosumer in Lodi District Heating network

Abstract

District Heating is acknowledged as an infrastructure which can exploit local heat sources by collecting heat where it is available and transporting it where it is needed. This opens doors to the birth of heat prosumers, a well-known concept in the power sector. The case of Lodi, a 45.000 inhabitants' city 30 km from Milano, offers an exemplary case study in this regard. After connecting a sport centre to the local district heating network, Linea Reti Impianti [1], the district heating network operator of Lodi, proposed the integration in the network of the solar thermal plant installed on the roof of the pool building, collecting all available solar heat. This connection has a twofold benefit: from the point of view of Linea Reti Impianti, an additional heat source is available-small in quantitative terms, but valuable in qualitative terms, solar heat being 100% renewable; from the perspective of the solar plant, a relatively high demand is constantly available, thus improving efficiency and avoiding stagnation in the collectors. The present article shows the results of technical investigations on the hydraulic connection and on the adopted control strategy, leading to the proposal for an improved control logic.