Performance and CO2 emissions assessment of a novel combined solar photovoltaic and thermal, with a Stirling engine micro-CHP system for domestic environments

This paper presents a novel installation where a set of photovoltaic modules and solar thermal collectors work in conjunction with a micro-CHP Stirling Engine to provide a reliable and self-sufficient energy system. A literature review showed that, while there are implementations of micro-CHP systems in household environments, there are no installations where the micro-CHP unit worked in conjunction with solar systems, photovoltaic and thermal. With the usage of Li-ion battery storage and a hot water tank for heat storage, as well as the micro-CHP unit, the system increases its reliability and independence from climatic conditions. The results obtained show that this system can supply 75.6% of the total energetic demand of a typical household, while achieving a reduction of 36.2% in the CO2 emitted to produce all the consumed energy in the system. The complete thermal demand has been met, while the usage from the electric grid has been required to meet 33.5% of the electric demand. However, with an increase in battery capacity to 20 kWh (doubling the actual capacity), the system is expected to become fully autonomous, as 31.8% of the electricity generated in the modules was exported to the grid due to saturation in storage capacity. In the thermal energy balance, sufficient heat was generated to provide enough energy for space heating or cooling, as well as domestic hot water.