In the fallout of the Fukushima disaster, Japan has rapidly escalated its commitment to solar energy. That presents a problem: utility-scale photovoltaic farms require a big chunk of real estate but Japan doesn’t have an abundance of land to spare. The solution: floating solar arrays.

Rendering of the PV Plant on the Yamakura Dam Reservoir (courtesy of Kyocera)

With three floating solar farms (1.2MW, 1.7MW, and 2.3MW) already producing power in the Land of the Rising Sun, Japan now embarks on the most ambitious one of its kind: a 13.7 megawatt floating array that dwarfs its largest ancestor by nearly 600%. When completed, it will be the most powerful waterborne PV farm in the world.

Kyocera recently broke ground (so to speak) on the new plant, which is expected to open by March of 2018. Located on the Yamakura Dam reservoir about 32 km east of Tokyo, the 180,000 square meter (44 acre) solar farm will consist of nearly 51,000 Kyocera PV modules. When operational, the plant will generate and sell up to 16 GWh of electricity to Tokyo Electric Power annually.

As I mentioned in another article, floating solar arrays are more efficient, due to the water’s cooling effect on the photovoltaic cells. They also reduce evaporation and algae growth, helping to conserve water and reduce chemical treatments. Using the Engineer’s Toolbox evaporation calculator and taking into account that the most significant evaporation occurs mainly on warm days, I estimated that this PV array could save more than 120 million liters (32 million gallons) of water every year.

We’re seeing a handful of floating arrays pop up around the world, with the first one - a 477 kW system at the Far Niente Winery in California - going live in 2008. The city of Holtville California is building a one megawatt floating PV array that will provide power for the water treatment facility while it reduces evaporation loss. The same company that’s installing the Holtville array also built the first aquatic solar farm in Australia. There are hundreds of open air reservoirs in the US alone. Floating PV farms seem like a better way to reduce evaporation than plastic balls. From Japan to Australia to the US to the UK, water utilities around the world are beginning to see the light: electricity production + water conservation + reduced chemicals = triple win.

Let it shine, let it shine, let it shine.



