This paper presents the build-up and long-term performance test of a full-scale Solar-Assisted Heat Pump System (SAHPS) for residential heating in Nordic climatic conditions. This particular SAHPS was developed within the EU project ENDCHOUSING, by predominantly using components and techniques that are available on the market. The analysis primarily focuses on system performance, with emphasis on Heat Pump (HP) and total system Seasonal Performance Factor (SPF), based on long-term and full-scale operation. Analysis shows that despite unfavourable building conditions, for low energy use and utilisation of a SAHPS, the system was successfully in full operation (for about 2 years) fulfilling heating requirements. Data processing of the series representing the full year period of 2007(February)-2008(February), presented a HP and total SAHPS performance of. SPF(HP) = 2.85 and SPF(SAHPS) = 2.09. The authors argue that with an optimised SAHPS control and operation strategy, additional use of circulation pumps and energy (electricity) could be vastly reduced, hence attaining a SPF(SAHPS) value that is in parity with the SPF(HP). As the Nordic (Swedish) Endohousing SAHPS has not yet been properly optimised/designed and installed in an appropriate house, the SPF_HP = 2.85 is considered satisfactory.