Simulation of Solar Thermal Systems with Seasonal Storage Operation for Residential Scale Applications

Buildings worldwide constitute one of the biggest energy consumers with 32% of the total final energy consumption, while in terms of primary energy consumption they represent around 40% in most countries according to the International Energy Agency. Of the various renewable energy systems that can be installed in the building sector in order to cover energy requirements (electrical and thermal loads), solar energy systems are currently the most widely used, mostly in the form of solar thermal and photovoltaic systems. Especially for locations with high annual solar radiation and temperatures, solar energy systems are already a viable alternative to fossil energy systems and are expected to become even more efficient and cost-competitive in the future. One of the problems associated with the use of solar thermal systems for space heating applications is the fact that solar potential is low during the heating period. To solve this problem solar systems that utilize Seasonal Thermal Energy Storage (STES) have been developed and are investigated for residential scale applications in the current work. STES implementation concerns the storage of heat in large facilities during the summer period for later use during autumn and winter, when heating load is in high demand.To that end the TRNSYS modelling software is used to simulate a typical Solar Thermal System with STES. The model calculates the space heating and domestic hot water needs of a typical 120 m2 single-family detached home in the city of Thessaloniki, Greece that has been built according to the latest building code. The contribution of the solar system, as well as the thermal load covered by the auxiliary conventional system is determined and the seasonal solar fraction is calculated.