Solar power or solar heat: What will upraise the efficiency of district heating? Multi-criteria analyses approach

Abstract

Solar energy has become a reasonable solution for power and heat production due to the continuous advancements of solar technologies. There are several solar system technologies available for heat production in district heating (DH) – solar thermal collectors (SC), photovoltaic (PV) panels for power production and self-power consumption coverage of heating plants, as well as photovoltaic thermal panels (PVT) which can generate both power and heat energy. In addition, the authors of this research consider the integration of heat pumps, which can convert surplus solar power from PV and PVT panels to heat when it is economically beneficial. The article presents a methodology for the comparison of different solar system designs for DH application and energy management strategies by developing hourly-based, mathematical solar system models, identifying several criterions and applying two multi decision-making methods. Sensitivity analyses is performed to evaluate the impact of the main variables changes – solar technology costs, DH heating network temperature, energy and heat tariffs. The results show that implementation of SC collectors is the most desirable solution in most of the analysed scenarios. However, if the DH heating network temperature is lowered by 10 °C, the combination of a solar power system adjusted with a heat pump is the most beneficial solution for self-power consumption coverage of a DH plant and surplus power conversion to heat.