Floating solar power | Ciel & Terre X Minna Denryoku

Ciel & Terre, a European leader of floating solar technologies, and Minna Denryoku, an independEnt Japanese renewable energy retailer, teamed up in 2018 to produce and distribute renewable electricity from floating solar photovoltaic plants on agricultural ponds while financially supporting local farmers in Minamiawaji, in the west of Japan.

The partners

Ciel & Terre: a European leader of floating solar technologies

Ciel & Terre is a French company established in 2006. First developing conventional photovoltaic systems on rooftops or ground-based plants, it started in 2011 to provide large-scale floating solar power plants, using a modular system developed by the company. Since then, Ciel & Terre has conducted floating solar projects in more than 30 countries around the world and became the market leader in terms of completed floating solar plants.

Floating solar panels

In this global development, Japan holds a special importance for the French company: the success of Ciel & Terre’s floating technology in Japan enabled the company’s approach to be legitimized worldwide. To accompany its development in the archipelago, Ciel & Terre started in 2013 to partner with well established Japanese companies such as Kyocera, Mitsubishi Chemicals or JFE Plant Engineering. Among other realizations, the Yamakura Dam plant built with Kyocera in 2018 is the largest floating solar plant in the country, with a capacity of nearly 14 MW. Ciel & Terre holds 70% of the Japanese market for floating solar systems, with more than 130 equipped plants representing 180 MW of power output.

Minna Denryoku, a Japanese power supplier committed to renewable energy

Minna Denryoku is a power operator established in 2011, after the Fukushima nuclear accident. The company focuses on renewable energy production and retail, aiming at connecting consumers and producers of renewable energy as a community.
Minna Denryoku developed a blockchain-based electricity distribution platform to enable the traceability of power from production to distribution, making it possible for consumers to choose their producers - towns, farms, schools or individuals. Minna Denryoku works with more than 500 renewable energy producers.

Minna Denryoku advert

The socio-environmental contributions of Minna Denryoku have been awarded by the Japan Science Technology Agency in 2019 and Japan’s Prime Minister Cabinet in 2021. It was also recognized as Certified Renewable Energy Provider by CDP in 2021.
The company now broadens its activities by providing a service to improve interior air quality and developing batteries with environmental and humanitarian considerations.

The partnership: floating solar plants with the local community

Ciel & Terre and Minna Denryoku came across each other in 2018, through the Embassy of France in Japan. Both companies were looking for new projects that could work with less governmental support, as the feed-in tariffs for solar power generation were going down. Their complementary skills made it natural for them to team up: while Ciel & Terre had the knowhow in power plant settlement and electricity production, Minna Denryoku would be able to bring its skills in the chain of renewable energy distribution.

The French and the Japanese companies decided to work together for the construction of floating solar plants on two agricultural ponds to supply local residents of Minamiawaji, in Hyogo prefecture, at the west of Osaka. This city of 45000 inhabitants had been working on developing local renewable energy since 1998.

In order to make the joint project successful, and based on its ethical sustainability approach, Minna Denryoku stressed on the importance of a trustful relationship between the two companies and the local residents. Many lakes and ponds in Japan are owned by self-governing bodies, mostly cooperatives of water users. The acceptability of floating solar plant projects therefore requires that the companies implementing the projects work in close cooperation with the local government and residents.

Floating solar panels


Local farmers found their interest in the project since pond maintenance costs could be covered with the rental income they would perceive from the power plant. To avoid potential damage to the ponds, Ciel & Terre set up a water level monitoring and alert system. It also provided six portable energy storage systems recharged by the floating plant, to be used in case of emergency. On its side, Minna Denryoku brought its expertise in promoting local consumption, allowing shops in Minamiawaji to be supplied with the electricity generated by the plants. These various services brought by the two companies helped gain the local trust needed for the project and allow its construction.

The first plant was connected to the local grid in September 2019, while the second one became operational in March 2020. In total, they generate more than 3 MW of power. To celebrate this first successful partnership as well as the positive relationship established with the local community, the companies co-organized in July 2021 an online tour of the Minamiawaji plant, allowing visitors from Japan and abroad to know more about this realization - the first floating solar plant in Japan with a traceability system allowing consumers to know their electricity is produced there.


Floating solar panels

Floating solar power only represents less than 1% of the electricity generated by Minna Denryoku, but the company intends to increase this share, considering the lower environmental impact and the interest expressed by customers in this type of renewable energy production.

Through their cooperation in Minamiawaji, Ciel & Terre and Minna Denryoku have been able to build a valuable shared experience on a project built without the support of the usual feed-in tariff. For Ciel & Terre, “Minna Denryoku and our company share the same pioneer and challenging mindset. This first experience will open future perspectives for other partnerships such as corporate power purchase agreements.”

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