Solar energy systems are currently the most widely installed renewable energy systems in the building sector in an effort to reduce the
energy consumption of buildings. This paper investigates solar potential regarding photovoltaic and solar thermal utilization in typical
residential buildings in order to identify their impact towards nearly Net Zero Energy Buildings (NZEB). Different options regarding the
installed capacity of photovoltaics and solar combi systems in various locations and climatic conditions are evaluated from a technical as
well as from an economic point of view. The results indicate that in all cases, photovoltaics are able to cover the annual electricity
demand of a residential building with a payback period of less than 7 years. In the case of solar combi systems, payback period ranges
between 5.5 and 6.5 years when compared with a conventional fuel oil heating boiler and 9 years when compared with a natural gas
boiler, providing at least 50% of the total heating demand of the buildings. In total, solar energy systems are able to cover at least
76% of the primary energy demand of residential buildings proving that they are a viable solution towards NZEB