The CO2-neutral self-supply of heat and electric energy is an important objective for new buildings. Two apartment buildings (7 units each) built in 2018 in Cottbus (Germany) according to the solar house concept will achieve solar fraction of up to 77% electrically and 65% thermally. The tenants receive all energy services, independent of consumption, financed by a flat-rate rent. The buildings were monitored over five years analysing the energy balances (heat and electrical) from the single flat up to the houses in detail. Additionally, the room climate of the flats was cross correlated with the energy consumption. Further, it was analysed whether the flat-rate rent led to wasteful behaviour of the residents. The results show that electricity consumption is comparable to the design values. Measured heating requirements, however, are significantly higher than planned. In addition to the high comfort demands of the residents, this is also due to technical reasons, which were revealed by the monitoring. Nevertheless, high solar coverage rates of between 70 and 77% were achieved for electricity and between 50 and 55% for heating demand. By integrating the surpluses of energy yields of photovoltaic panels into a neighbouring district, it was possible to increase the level of self-consumption to >80%. Finally, the monitoring identified a number of points that would ensure even greater efficiencies in similar projects in the future. Individual results and proposed improvements for system design are presented in detail in this contribution.