LAUSR

Abstract The article presents long-term results of experimental tests of a hybrid installation (HI) consisting of four heating devices, three of which use renewable energy sources (RES). The HI is operating in a residential and retail building located near Krakow, in southern Poland. There is little experience with the operation of such installations, therefore, the purpose of this paper is to discuss significant aspects related to the implementation and operation of HI in a moderate, transitory climate. The research was carried out from 2011 to 2017. The share of solar collectors in annual heat generation ranged between 7.4% and 12.5%, with an average annual efficiency to 38%. The annual performance of a ground-source heat pump in the heating mode ranged from 3.5 to 3.8, and in the passive cooling mode, it reached up to 11.87. The annual efficiency of a gas condensing boiler was from 77.5% to 82.2%. Annually, the largest amounts of heat were supplied by a biomass boiler i.e. from 30% to as much as 50%. The paper disclosed clearly that it is possible to reach in HI high level of RES share in heat generation. A key issue requiring further research is the development of appropriate algorithms in the control systems of HI.