Taisei Corporation has demonstrated that a building can operate entirely on solar power by combining PV generation with a hybrid storage system integrating batteries and low-pressure hydrogen at a test facility in Yokohama. An EMS-enabled setup using lithium-ion batteries and PEM electrolysis balanced short- and long-term energy supply and demand, enabling year-round renewable operation, according to the company.
Japanese industrial and construction conglomerate Taisei Corporation has demonstrated that a building can be operated entirely on solar power by combining photovoltaic generation with a hybrid energy storage system integrating batteries and low-pressure hydrogen.
The pilot project was developed at the company’s Zero Energy Building (ZEB) test facility located in Totsuka Ward, in the central-western area of Yokohama City, Kanagawa Prefecture, Japan.
The system is based on an energy management system (EMS) developed by Taisei, which coordinates lithium-ion batteries for short-term storage and a low-pressure hydrogen storage system for long-term, seasonal energy shifting.
The EMS continuously balances supply and demand by directing surplus PV power either to immediate building consumption, battery charging, or an electrolyzer for hydrogen production. When solar generation is insufficient, stored energy is supplied back to the building either from the batteries or by converting hydrogen into electricity via fuel cells. The storage system consisted of two 450 kWh lithium-ion batteries, a 5.0 Nm3/h proton exchange membrane (PEM) electrolyzer, a 2,000 Nm3 hydrogen tank, and a 5 kW fuel cell.
The company said the effectiveness of this approach was confirmed through real-world operation starting in winter 2023. During a representative sunny day in June 2024, with 12.1 hours of sunlight, the system generated 444 kWh of electricity. Of this, 57 kWh was consumed directly by the building, while 155 kWh was stored in batteries and later partially discharged to cover nighttime demand. The remaining 232 kWh was used for hydrogen production and storage for longer-term use.
In contrast, on a winter day in February 2025 with shorter daylight hours, the system generated 297 kWh of solar power. Electricity demand during the evening and early morning was met using hydrogen stored in previous seasons, with fuel cells supplying 168 kWh to the building.
“The application of our EMS demonstrated that both short-term and long-term supply–demand balancing can be reliably achieved as planned by coordinating battery storage and low-pressure hydrogen storage in response to real-time energy demand and generation conditions,” the company said in a statement, without providing further technical details.
Looking ahead, Taisei plans to further improve the efficiency of both its EMS and hybrid storage system. The company aims to establish a fully optimized framework for year-round renewable energy operation in buildings.
Beyond this project, Taisei is actively participating in hydrogen production, storage, transport, and utilization demonstration projects as part of its broader commitment to decarbonising Japan’s energy system. It is currently involved in hydrogen supply chain trials that connect renewable electricity with hydrogen production and storage for building and regional energy use.
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