Sensitivity Analysis of Solar District Heating Systems

The economic consideration of large-scale solar thermal systems to support district heating is often a challenge. Due to the necessary planning efforts and high investment costs of the solar thermal components, the solar-supported scenario is often ruled out. Therefore, the present work deals with a tool where an approximate economic sensitivity analysis can be carried out at the beginning stage of the planning process. This includes the calculation of the levelized cost of heat (LCoH) and the comparison with conventionally operated district heating systems. Further, by using cost functions of solar thermal systems and thermal energy storages, a preliminary calculation of the investment costs of solar supported district heating in different variations is made possible. The calculation of the LCoH considers the energy prices, lifetime of the components, costs for CO2-emissions, increase of energy prizes, etc. By varying the mentioned parameters, a sensitivity analysis of the LCoH is performed and analyzed over the lifespan of the system. To validate the tool, results from completed projects were recalculated and interpreted. To do this, different scenarios are defined, LCoHs are calculated and a sensitivity analysis for each scenario is carried out. The results show a consistent correlation between the individual project results and the calculation methods.