Sonnedix Japan announces first BESS project
04 November 2025
TOKYO, Japan – Sonnedix Japan, on behalf of the Sonnedix Group of companies (Sonnedix Group), has announced the construction of a 125MWh Battery and Energy Storage System (BESS) in Oita prefecture, its first BESS project in the country. This investment is a testament to Sonnedix’s continued commitment and expansion into battery storage and hybrid renewable solutions.
The project will be co-located with an existing 39MW PV plant, enabling the optimisation of solar generation as dispatchable, market-responsive power. Construction activities started in October, with commercial operation targeted for November 2026. The Engineering, Procurement and Construction (EPC) partner for the Oita BESS project is Toshiba Energy Systems & Solutions Corporation, while Tesla Japan GK is providing the Battery Energy Storage System (BESS), made up of Tesla Megapacks. Osaka Gas Co., Ltd. will be responsible for the market interaction of the generated electricity.
In parallel with project development, a refinancing process was undertaken to optimise the project’s capital structure and enhance its long-term financial sustainability. The refinancing arranged by MUFG Bank, Ltd. consists of a total non-recourse facility of JPY 21.4 billion.
While Sonnedix Japan has historically focused on solar, the company is broadening its portfolio across the renewable energy spectrum and investing in advanced energy storage solutions. The announcement comes shortly after the Sonnedix Group began construction of its first BESS project in Italy, bringing the business to >1GW of total, co-located BESS capacity globally.
Sonnedix Japan has a well-established presence as a trusted provider of renewable energy in the region. It currently operates 25 solar PV projects in the country, with over 500MW controlled capacity.
Axel Thiemann, CEO of Sonnedix, commented:
“The construction of the Oita battery storage project is a testament to our trusted Japanese partner’s alignment with the Sonnedix Group’s strategic focus on hybridization. With a strong pipeline of projects underway, the entire Group is focused on creating more co-located battery solutions that will allow for greater responsiveness to energy markets. BESS will continue to play a key role in the Group’s evolution, creating a more flexible and balanced portfolio that will contribute to both energy security and climate neutrality goals.”
Tomomichi Kageyama, Managing Director of Sonnedix Japan commented:
“We are pleased to announce NTP on this project, which solidifies Sonnedix Japan’s excellent track record as a forward-looking energy producer in Japan. With our extensive knowledge of the Japanese energy landscape, and long-term footprint in the market, we are well positioned for continued sustainable growth. It is a pleasure to be working with esteemed partners Toshiba and Tesla, in addition to our existing investment partners Osaka Gas and Sonnedix Group, who share our commitment to delivering value to our customers, while supporting Japan’s clean energy transition.”
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Notes to Editors
About Sonnedix Japan
Established in 2013, Sonnedix Japan is a developer, asset manager, and operator of mega-solar projects in Japan, and the Japanese operator for investments made by the Sonnedix Group (www.sonnedix.com). At present, Sonnedix Japan has a total capacity of over 500MW, including 25 operational solar PV plants across the country.
For more information, please visit www.sonnedix.jp
About Sonnedix
Sonnedix is a global renewable energy company with almost two decades-long trajectory of sustainable growth. Sonnedix develops, builds, and operates renewable energy projects for the long-term, delivering innovative, tailored, and fully renewable, energy solutions to our customers.
Sonnedix currently has a total capacity of 12GW, with almost 1GW under construction and a development pipeline of 6.8GW, across Chile, France, Germany, Italy, Japan, Poland, Portugal, Spain, UK, and USA. The company continues to expand its global footprint across OECD countries, through acquisitions and development of renewable energy projects.
For more information, please visit www.sonnedix.com