Unity is strength, especially when it comes to renewable sources. This is demonstrated by an innovative project made in Italy that tested the combination of photovoltaic and hydrogen to make a home energy self-sufficient.
The heart of the system is a solid oxide fuel cell powered by “homemade” hydrogen using solar energy. The results are surprising in terms of efficiency and open up new scenarios for the integration of thegreen hydrogen in the residential sector. An all-Italian case history that traces the path towards a cleaner and more distributed energy future.
Photovoltaic and hydrogen: a winning combination
The research team1 composed of university researchers and startup experts SolydEra, specialized in solid oxide fuel cells, of the consortium Stress and University of Sannio and Molise, has installed a 1 kW cogeneration system in a small 80 m2 nearly zero energy (NZEB) cottage located on the campus of theUniversity of Sannio in Benevento.
In addition to the fuel cell system, the home is equipped with a 5,3 kW photovoltaic system on the roof combined with an 11,6 kWh lithium battery, an air-to-air heat pump for heating, cooling and domestic hot water, a 2,2 m2 solar thermal collector and horizontal geothermal probes.
Green hydrogen produced and stored on site
La solid oxide fuel cell (SOFC) used, with dimensions of 1,2 m × 0,5 m x 0,8 m, is powered purely by hydrogen, with a flow of approximately 12 L/min at 15-25 millibar.
Hydrogen is stored in 8 external high-pressure cylinders (200 bar) for a total of 64 Sm3, enough to guarantee autonomy for several days. A hybrid inverter manages the energy flows between photovoltaic, battery, fuel cell, electricity grid and domestic utilities.
Image: University of Sannio, International Journal of Hydrogen Energy, CC BY 4.0
Photovoltaic and hydrogen, record efficiencies and energy surplus
From the tests carried out, the system has demonstrated that it can achieve an electrical efficiency of up to 48% and an overall efficiency of 93%, thanks also to the recovery of the heat produced by the electrochemical reaction in the cell. Under particular photovoltaic production conditions, the system is able not only to satisfy domestic electrical loads, but also to feed the surplus into the grid.
Another advantage is the ability to modulate the fuel cell power to compensate for variations in solar production, ensuring a stable and programmable electricity supply. Among the limitations highlighted by the researchers, the long start-up times (about 24 hours) and the need for highly specialized personnel for management.
Fuel Cells: A Future in Residential?
The study, published in the journal International Journal of Hydrogen Energy (I link it here), demonstrates the technical feasibility of integrating hydrogen-powered solid oxide fuel cells in residential settings. A significant step forward towards decarbonizing the building sector, responsible for approximately 40% of CO2 emissions.
However, for this technology to spread on a large scale, some barriers will need to be overcome: in addition to those related to safety, there are still high costs and the lack of infrastructure for the production and distribution of green hydrogen. But the advantages in terms of efficiency, flexibility and reduction of emissions are an incentive to continue research and development in this direction.
The combination of photovoltaics and hydrogen could prove to be an ace in the hole to reach the ambitious decarbonization goals set by the EU for 2050. And Italy, with pioneering projects like this, is a candidate to play a leading role in the energy transition of the Old Continent. The challenge is launched, the game has just begun.
The future of energy, in any case, also passes through the roof of our house.
- Rose Francesca De Masi, Valentino Festa, Daniele Penchini, Silvia Ruggiero, Giuseppe Peter Vanoli, Alberto Zinno ↩︎