Energetic and financial sustainability of solar assisted heat pump heating systems in Europe

The objective of this study is to compare energetically and financially a solar assisted heat pump heating system powered by flat plate collectors with a conventional air source heat pump system for twenty European cities. The examined buildings have 100 m2 floor area and they are identical among the examined cases in order to perform a comparison under the same terms. Only the insulation thickness varies, examining two insulation scenarios with 4 cm and 8 cm insulation layer thickness. According to the final results, the electricity savings using the solar assisted heat pump system are ranged from 30% to 40%, indicating great sustainability in both insulation scenarios. The COP in the solar assisted systems is found close to 4 and for the conventional air source systems close to 2.5. The solar assisted heating system is proved to be also the financially optimum solution for the majority of the examined cities and especially in low insulation cases. More specifically, this system is proved to be ideal for cities with high solar potential and not extremely low heating loads. The simulation tool is TRNSYS and the analysis is performed for all the winter period.