Operational Analysis and Detailed Monitoring Results of Solar Thermal Heat Pump Combinations integrated into Austrian District Heating Networks

In 2009 the Austrian Klima- und Energiefonds started a funding programme for the development and further market penetration of large-scale solar thermal systems for industrial and commercial applications. Funding could be obtained for innovative system concepts between 100 and 10,000 m². In order to ensure high quality and functionality the most interesting projects in terms of innovation and replicability were chosen for a 12 months solar thermal system monitoring, analysis and optimization. Between September 2009 and September 2017 301 application forms were successfully handed in, summing up to a total collector area of around 150.000 m². Of these, 100 projects were equipped with additional sensors for monitoring in which 41 furthermore can be assigned to the solar district heating category. Of the 41 SDH-systems, a total of 6 systems were implemented as solar thermal heat pump combination projects. These systems are characterised by a wide variety of system designs with collector areas between 255 m² and 2,048 m² as well as heat pump capacities between 160 kW and 2,400 kW. Solar fractions between 3% and 29% reflect furthermore the broad spectrum of solar thermal heat pump combinations that have been realised in recent years in Austrian district heating networks. In this paper monitoring results covering both the characteristics of the solar circuit as well as the entire energy balance of selected SDH-heat pump combination including auxiliary energy flows, heat losses and parasitic energy consumption are presented.