Solar Thermal Potential in Representative Swedish District Heating Systems : A Comparative Case Study with Dronninglund, Denmark

This master thesis analyzes the feasibility and benefits of integrating solar thermal energy into Swedish District Heating Systems (DHS) and compares the results to the successful implementation of the Dronninglund solar DHS in Denmark. Five Swedish DHS systems are evaluated in terms of their demand profiles, load duration curves, and technical potential for solar integration. Principal performance indicators such as collector area, seasonal thermal storage requirements, CO₂ emission reductions, Levelized Cost of Heat (LCOH), and payback period are calculated for various solar fraction scenarios (20%, 30%, 50%, and 70%). The results confirm that System 4, with the minimum and flat annual heat demand, is best suited for high solar fractions with minimum infrastructure scaling. In contrast, Systems 3 and 5, promising significant scale CO₂ savings, require large collector and storage investments. System 2 seems to be an appropriate fit for solar thermal integration. Intermediate solar fractions, 30% and 50% are found to be optimal in all systems. The findings are that solar thermal integration is technologically feasible and environmentally friendly in Sweden, especially with seasonal storage. Economic viability is a function of system scale, solar share, and demand stability.