Northern and Eastern Europe have high district heating (DH) market penetration, but solar thermal energy remains underused. This study explores combining DH with solar thermal and heat pumps to boost solar heat use. A methodology was developed to measure how solar-driven temperature fluctuations affect heat pump performance. TRNSYS 18 simulations, field data, and experiments show that combining photovoltaic-thermal collectors with a brine-to-water heat pump in low-temperature DH can yield up to 7.6 times more energy than traditional systems. Findings support smarter design of future DH networks.