Distributed Energy Magazine

Flotovoltaics

Inside the world of floating solar technology

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Credit: Ciel & Terre; International
A floating solar plant installed in an irrigation reservoir in Shimane, Japan.
Within the past few years, the floating photo­voltaic (FPV) market has grown expo­nentially popular as a real alternative to traditional solar methods. Commonly known as “floatovoltaics” or floating solar, standard PV modules are installed on top of inland, compounded, and unused man-made bodies of water, including industrial water ponds, dams, irrigation reservoirs, water treatment or drinking water surfaces, aquaculture farms, and quarry or mine lakes. Water- and energy-intensive industries such as wineries, hydroelectric dams, and public utilities have seen enormous benefits through this unconventional solution.

By taking advantage of unused water spaces, floatovoltaics turn those areas into profitable and eco-friendly energy generating areas. Japan was the very first to heavily invest in the floating solar industry and has since seen enormous benefits that position the country in a better economic and environmental state. After the success of many of Japan’s floating solar projects, other countries have followed. Floating solar has expanded to the US, South America, China, South Korea, ASEAN countries, the UK, and Portugal. There is an estimated 100 MWp of floating solar installed worldwide, expected to increase to 5,000 MWp by the end of 2017.

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Why Was Japan an Early Adopter in Floating Solar?
After the Fukushima disaster in March 2011, Japan decided to turn away from nuclear energy and give priority to clean and safe energy sources. In June 2012, Japan’s Ministry of Energy, Trade, and Industry (METI) approved a system of feed-in tariffs for renewable energy generation, which favored solar development and shifted away from a reliance on nuclear power, oil, and liquefied natural gas.

Additionally, Japan has faced domestic economic issues due to a lack of usable land. The country spends $60 billion annually on agricultural imports alone and depends on other countries to supply most of their resources. This continues to cause high market prices and taxes for Japan’s population.

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Eventually, Japan needed to refocus its efforts on renewable energy in order to tackle its environmental and economic issues. By doing so, it would relinquish its reliance on imported agricultural products and fossil fuels. Unfortunately, many renewables like wind, hydro, and biomass proved to be unpopular options. Wind requires the need for more land, which Japan already lacked. Hydroelectric production often requires heavy construction work, which directly affects the natural environment, while biomass plants struggle with low efficiency to convert fuel to power.

Among all the renewable options, solar was most favored with positive economic and political policy. Traditional solar options like ground-mounted and rooftop systems met demands, but still lacked the ability to conserve land. Floating solar proved to be an ideal up-and-coming solution to tackle multiple environmental and economic issues, allowing Japan’s agricultural industries to thrive and meet the demands of its general population. The Japan External Trade Organization has played a major role in this initiative by attracting foreign investments and providing support programs for companies with the right technologies and ideas, like green companies, to settle there.

Besides preserving valuable land space, a number of other environmental benefits presented themselves when using floating solar. One advantage includes covering a significant area on a body of water, which conserves water by reducing evaporation. The shading from the panel also reduces algae growth, which improves water quality. Contrary to nuclear power, local communities do not have to be afraid to live near a floating power plant, since a simple switch offers an easy way to start and stop energy production if needed. Overall, this solution presents no risk or dangers to the wildlife and surrounding environments when implemented, as long as materials are eco-friendly and recyclable.

On the economic side, the installation process is the smoothest and fastest compared to other solar infrastructures. The installation process for a floating system is extremely simple. A framing structure, similar to a ground-mounted PV system, supports the PV modules. The Lego-like modules are assembled offshore where the main float, which supports the PV module, and a secondary float, which maintains buoyancy, are attached through a connection pin. This results in a floating island that the assemblers can push into the water. The process requires no heavy tools or land excavations, which also allows easy site rehabilitation if necessary. Overall, the implementation or dismantling of a floating solar PV power plant has no negative impact on the environment, because it does not require foundations and does not change the reservoir’s original features.

Case Study: Isawa Ike, Japan
According to the Japanese Ministry of Agriculture, there are about 200,000 irrigation ponds in Japan. This presented unlimited opportunities to install floating PV plants across Japan while enabling owners of these water bodies to convert unused surfaces into green power production spaces.

For instance, a floating solar plant installed in an irrigation pond in Isawa Ike in the Tokushima Prefecture proved to be an ideal location to preserve land space for agricultural purposes. Construction for this 1.35MW project ended in September 2016. With 2,340 solar panels installed on the water, the Isawa Ike plant has a 632-kWp capacity. It can now generate up to 756 MWh per year—equivalent to 230 homes powered.

The most important step of this project was to ensure the anchoring system could take into account resistance to environmental impacts and time, local regulation constraints, and economical optimizations. Therefore, accurate bathymetric information was crucial to its success. After a preliminary study, the floating island was moored at more than 6 meters in depth, considering that it has to deal with a water level variation of 6 meters. The 2,340-panel floating PV array covers 57% of the existing water and was designed to withstand more than the maximal wind speeds up to 142 km/h registered at this site.

Local manufacturing of the materials avoided unnecessary international transportation and carbon emissions while stimulating local employment. Overall, the floating system in Isawa Ike is able to save over 325 tons of carbon emissions every year.

Conclusion
Solar energy has quickly developed into a feasible and practical solution for those seeking to adopt a renewable option. Despite the recent political state, many businesses and industries have fully understood the necessity to go green, and are more likely to do so now that prices for renewables are competitive with oil and gas. These companies see a higher return on investment for renewables as prices continue to drop.

With the help of FPV, the solar market continues to diversify into different sectors and industries. For example, we will be seeing more hybrid hydroelectric and floating solar systems worldwide because the hydroelectric industry faces persistent droughts and criticism for construction on new dams due to their heavy environmental impacts.

Early successes of floating solar in Japan have attracted other island nations like Taiwan, Singapore, and the UK. These countries were among the first to adopt this alternative solar option and are now part of the largest investors in floating PV plants in the world. The attractiveness for island nations is obvious, but urbanized areas are starting to slowly follow the floating PV trend. The democratization of floating solar takes time, which is why some nations have not yet adopted it. Greater awareness amongst investors, banks, installers, public agencies, regulators, and landowners is still needed.

Projections are difficult to make for the floating solar market, but developed countries will likely be the first to adopt floatovoltaics since financing is more easily available. Then it will slowly spread to other countries where the use of well-positioned water bodies is more practical to take advantage of. Once floating solar gains a longer track record, investors will follow without hesitation, especially with the knowledge that it is a cheaper and easier option compared to traditional solar PV. Therefore, strong public policy supporting specific industries, private companies, and public entities is important to stimulate the growth of different energy mixes, especially in solar, where energy is always abundant. Positive reinforcement, such as the policies made by Japan’s METI, needs to be made now and not in response to the next disaster. BE_bug_web

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Comments

  1. Excellent approach, I appreciate the algae inhibition, but wonder what other consequences follow large scale shading on smaller waterbodies like we have in SW Florida where I am…

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