SMFL Mirai Partners, Fujimaki Construction, and Toshiba Plant Systems & Services partnered to develop two extra high-voltage grid-scale battery storage projects in Nagano Prefecture totaling 84.4MW/250.75MWh, the companies announced on June 8, 2026.
According to the statement, the projects include the 52.45MW/160.48MWh Kijimadaira Power Storage Station in Kijimadaira Village and the 31.95MW/90.27MWh Hachisu Power Storage Station in Iiyama City. Construction of the former began in June 2026, while groundbreaking for the latter is scheduled for August 2026. Both facilities are targeted for commissioning in FY2028. They will be aggregated by Toshiba.
SMFL Mirai Partners leads the project overall and is responsible fundraising and asset management. Toshiba Plant Systems & Services will handle engineering, procurement, and construction (EPC). It will also support grid connection coordination with the utility. Fujimaki Construction has been in charge of land rights acquisition, local permitting, and civil engineering.
The partners said they selected the sites in 2023 and signed EPC contracts in March 2026.
Kijimadaira Power Storage Station and Hachisu Power Storage Station are held through the special purpose company (SPC) OPTIRON Hokushin LLC, in which SMFL Mirai Partners holds a 61% economic interest. Fujimaki Construction and Toshiba Plant Systems & Services hold 34% and 5% interests, respectively.
The Sumitomo Mitsui Finance and Leasing subsidiary targets a 1GW battery storage portfolio by FY2031. It previously acquired high-voltage assets from Sun Village and West Energy Solutions. The company also holds stakes in multiple Renova-led extra high-voltage projects and is participating in the SPARX Group-led 22.7MW/70.2MWh SGET Niigata Power Storage Station, which is scheduled for commercial operation in May 2028.
