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Japan will soon have the world’s largest floating solar power plant

12 September 2014
Japan will soon have the world’s largest floating solar power plant

LONDON: Japan will soon have the world’s largest floating solar power plant, signalling increasing adoption of the efficient and innovative technology in Japan, which is due partly to lack of space on land.

“The world’s largest floating solar power plant,” as announced by Kyocera and Ciel et Terre International, will have a total capacity of 1.7 megawatts (MW), and be installed on Lake Nishihira, in the region of Hyogo.

A second park with a capacity of 1.2 MW will also be installed on Lake Higashihira, in Kato city, with the companies aiming to install floating solar plants with a total capacity of 60 MW by the end of March 2015. 

Solar photovoltaic (PV) technology is becoming more wide-spread in Japan, driven in part by the closure of the country’s fleet of nuclear plants following the Fukushima disaster. As the graph below shows, total capacity has moved from just 19 MW in 1992 to 13,532 MW in 2013 - more than double the previous year.

Japan PV

Image: The Climate Group, data from EPIA report “Global Market Outlook for Photovoltaics 2014-2018” and IEA eport “National Survey Report of PV Power Applications in Japan 2012”

This huge increase marked Japan as the world's second biggest solar PV market in 2013, following China with 11.8 GW. By comparison, in the same year the US connected 4.8 GW to the grid from PV power plants. Japan also represents 10% of total global PV capacity, compared to China's 13%.

The upward trend, according to the European Photovoltaic Industry Association (EPIA), will continue at the same level or even slightly more this year too. 

Japan's success in solar technology was also boosted by the implementation of new feed-in tariff policies, says EPIA. The Ministry of Economy, Trade and Industry estimates an increase in the amount of electricity through this system of 32 to 35 million kW.

The Ministry is also committed to promoting technological development and the use of heat from renewable energy, aiming to make the ratio of renewables in primary energy supply 10% by 2020.

Floating solar

However, with a landmass slightly smaller than California and a population density closer to India, this expansion in PV collides with the lack of space. Thankfully Japan is surrounded by sea and has many water reservoirs to cater for its seasonal variation in rainfall levels, so is experimenting more frequently with floating PV systems.

Not only is floating solar more convenient, it is also more energy efficient. A recent study by Korea Water Resources Corporation (K-water) says the technology is more efficient because it has a lower temperature during the day when compared to overland PV modules. This is due to the reflection of light from the water surface, which keeps the PV modules cooler.

FPV studio

Image courtesy of Korea Water Resources Corporation, from "A study on power generation analysis of floating PV system considering environmental impact"

The corporation states that compared to overland PV, the efficiency of the floating PV system is actually superior by 11% and more, as shown in the graph above. However, this study excludes data acquired when the system is moved by wind which has a significant effect on generation efficiency, so the report suggests the next step in developing this technology is to counter this challenge.

Seperately, a study from the National University of Malaysia demonstrates the efficiency of the technology is continuing to improve, asserting that by passing water through a simple and cost-effective aluminium box at the back of the modules, the system has a “higher efficiency and total power gain than the conventional PV module.”

Innovations in floating PV technology and increasing adoption in Japan offer clear evidence that barriers to clean technology can be overcome, when there is synergy with the policies of a government that is actively committed to finding clean, rational and affordable energy solution for its citizens.


Image: Kagoshima Nanasujima mega solar power plant, Kyocera Corporation

Climate Week NYC, from September 22-28, is a global event which offers the opportunity to discuss innovations such as this. Political and business leaders will share their visions of how to balance business and the necessity of a cleaner world. For a full list of Climate Week NYC events, please visit and follow the conversation on Twitter using #CWNYC.

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