This article presents the monitoring results of an existing large scale system that combines heat pumps with unglazed solar collectors (used for heat production or as heat source for the heat pumps). The system provides space heating and domestic hot water to a new housing complex (similar to 10,000 heated m(2)) in Geneva, Switzerland. Detailed monitoring of one of the blocks (similar to 1000 heated m(2), 32 inhabitants) enables to characterise the behaviour of the system (building demand, control strategy, temperature levels) and to determine the energy flows as well as the performance of the system. The results show a very low space heating demand for Switzerland kWh/m(2)/yr), and an unusually high domestic hot water consumption (similar to 50 kWh/m(2)/yr). The measured seasonal performance factor of the system, including backup electric heating and heat source circulation pump, is 2.9 for 2012 (average of 2.5 in winter and 4.4 in summer). This result can partly be explained by the high domestic hot water consumption, which implies a heat production at high temperature. This project is part of TEA SHC Task 44 "Solar and Heat Pump Systems". (C) 2015 Elsevier Ltd. All rights reserved.