Hybrid solar thermal and heat pump systems in industry: Model based development of globally applicable design guidelines

Solar thermal heating systems and heat pumps are key technologies for decarbonizing low temperature industrial heat demand. Fluctuating solar irradiance, limited heat source capacity or limited availability of renewable electricity often limit the potential of the single technologies. To maximize the share of renewable heat supply, the combination of both technologies is a promising option. This study takes the first steps towards filling the research gap of missing guidelines for preliminary design or feasibility studies. A simulation tool based on idealized component models is used to compare technical and economic performance for 30,240 parameter combinations, that define various global reference applications, system designs, and economic frameworks. The heat sink and source temperatures, and the energy prizes have the highest impact on the economic performance. The potential for technical optimization is small. If the fraction of both heat generators together is close to 100 %, SCOP differences between different hydraulic concepts are neglectable. The most viable option for optimizing the system's LCOH is to reduce the heat pump capacity to about the half of the annual peak load. Due to recent increases in energy prices, a complete decarbonization is economically feasible without subsidies for most of the applications studied.