Port Inc. will develop four additional high-voltage grid-scale battery storage projects, bringing its total in operation and under development to 17, the company announced on September 29, 2026. On October 2, 2026, it disclosed aggregation agreements with Sassor and Tensor Energy.
According to the statement, the assets will be about 2MW/8MWh each. They will be located in Otawara City in Tochigi Prefecture, Iruma and Hiki disctricts in Saitama Prefecture, and Kitakanbara District in Niigata Prefecture. Construction of all four is scheduled to begin around November 2026, with commercial operation following in phases between April and July 2027.
The company said it would invest approximately 1.6 billion yen in the four projects. It plans to secure funding from multiple financial institutions and possibly use proceeds from a third-party share allotment announced on September 15, 2026.
Sassor and Tensor Energy, both of which will optimize the trading of undisclosed assets scheduled to begin operation in 2027 in the Tokyo TSO area, join GridBeyond and Second Foundation in Port’s lineup of aggregators.
Separately from the four newly announced projects, Port is developing 10 other grid-scale battery storage facilities including four in the Chubu TSO area, three in the Kansai TSO area, two in the Kyushu TSO area, and one in the Tokyo TSO area. Two of them are shorter-duration 2MW/5MWh assets, the performance of which the company plans to evaluate against the standard four-hour configuration.
In 2025, Port built three demonstration assets in Gunma Prefecture, which turned a profit in their first fiscal year and led it to formally enter the grid-scale battery storage business in April 2026. The TSE Growth-listed company said it plans to add about 10 assets to its portfolio annually.
