Experimental investigation of reversible solid oxide fuel cells coupled with a domestic load and a photovoltaic system for seasonal storage purposes

Reversible Solid Oxide Cells (rSOCs) can provide a significant contribution as a key element in energy storage systems. In the present study, the behaviour of a system consisting of a rSOC stack, a domestic end user and a photovoltaic (PV) plant has been investigated. The PV plant is employed to supply power to the household, with the excess of renewable power being supplied to the rSOC operating in electrolysis mode for hydrogen production. Conversely, in case of lack of PV power to fully meet the household's demand, the missing power is provided by the rSOC operating in fuel cell mode. Firstly, a domestic load of a 4-people house placed in Rome was considered, by simulating its electricity demand profile throughout the year with an hourly resolution; furthermore, the specific power production profile of a PV plant placed in Rome in a typical meteorological year (TMY) has been simulated. Assuming a rSOC system and a hydrogen compressor with standard performance found in literature, the size of both the rSOC and PV plant enabling self-sufficiency were identified. For both domestic load and PV plant, the profile of every month's most representative day have been found: the supply and demand profiles have been appropriately downscaled and an experimental demonstration of an electrolyte - supported rSOC (active area 16 cm 2 ) working in such a system under the abovementioned conditions has been performed in an overall 24 day-long test, aimed at evaluating the response and degradation of the current state of art Solid Oxide technology in the said operating scenario. The results show the ability of the cell to react promptly in the wake of a rapid input power or load change, hence evidencing its overall very good response in variable working conditions as well as its great stability once a new set point has been imposed. The degradation analysis led to state that electrolysis proved to be the most challenging working condition, but the continuously-decreasing performance loss towards the last stages of the 576 h-long test potentially suggests that, at chemical level, the cell's components have reached their optimal operating state. • Renewable system using rSOCs and PV for residential energy self-sufficiency. • Excess PV energy stored as hydrogen for seasonal power via fuel cell. • 7.7 kWp PV capacity and 38 kg H 2 storage for energy autonomy. • 576 h rSOC test showed manageable degradation mainly in first 120 h. • Electrolysis caused about 2x more degradation than SOFC operation.