Measurement Results of a District Heating System with Decentralized Incorporated Solar Thermal Energy for an Energy, Cost Effective and Electricity Grid Favorable Intermitting Operation

An overall measurement analysis of a district heating system with distributed decentralized solar thermal systems is given for the period of in total one year. Due to the solar thermal yield of each building supply system the district heating system results in an intermitting operation especially during summer period of time. By implementing intelligent operation modes developed by Elci (2018) and Elci et al. (2015) DH supply of each building connection unit are to harmonize over time to enlarge periods of intermitting operation of the DHN especially by taking periods of a high share of PV in the electricity grid into account. Focus in the analysis carried out is put to energy efficiency and temperature levels of each building supply system and it is shown that the energetic design key data are met. Operational performance instead is related on the analyzed high return temperatures of the systems due to hydraulic unbalanced issues and is therefore away from the expected based on the concepts for energy and cost efficient operation modes by Elci (2018) and Elci et al. (2015).