Floating solar system specialists, such as Ciel et Terre, for example, has...

Kyocera, the Japanese solar-to-electronics giant, has signalled growing interest in water-borne PV projects with the launch of the world’s biggest floating solar array.

Construction of the 1.7MW plant began this September at Nashihira Pond, Kato City, in Japan’s Hyogo Prefecture. A second plant, being built on the nearby Higashihira Pond, will add a further 1.2MW.

The projects, which see Kyocera partnering with Century Tokyo Leasing for finance and Ciel et Terre, a French developer, for the floating platforms, are far from the first experiments in water-borne PV.

Ciel et Terre, for example, has already installed floating arrays elsewhere in Japan and in Piolenc, France. Singapore has a small test project and earlier this year India’s National Hydro Power Corp was said to be mulling a 50MW plant in Kerala.

Growing interest in floating PV may be down to some significant benefits that the concept offers. For a start, many large bodies of water may have fewer alternate uses than neighbouring land, particularly in built-up countries such as Japan.

Most importantly, though, the cooling effect of water can help increase output. Young-Kwan Choi, of the Korea Water Resources Corporation, this year published a study comparing floating and land-based PV.

“The floating system has 11% better generation efficiency than overland PV,” he concluded.

Here Ichiro Ikeda, general manager of the solar energy marketing division of Kyocera’s corporate solar energy group, talks about why these benefits are leading the company to pursue further floating PV opportunities.

Q. Why has Kyocera decided to create floating solar power plants? What are the advantages of this approach?

In Japan, there is a lack of land suitable for construction of utility-scale solar projects.

Along with the promotion of rooftop projects on factories or large buildings, Kyocera is also promoting floating solar plants to increase the use of solar power and efficient use of land and water resources.

Due to the cooling effect of the water on both the panels and the electrical equipment, all water resistant, floating solar plants are expected to yield a higher power output than conventional solar installations.

Also, by shading the reservoirs with the solar panels, water evaporation is decreased, which conserves water resources, and growth of algae is slowed, which improves the quality of the water.

Furthermore, the construction time and labour for floating solar projects is minimal compared to land-mounted or roof-mounted solar projects.

Q. What are the challenges associated with locating solar PV plants on water?

There are a few factors unique to floating solar installations as compared to conventional systems, such as that the electrical equipment, modules and wiring, must be water resistant.

Effects on the environment, mainly water quality, must be considered, and the annual fluctuation in reservoir water levels must be taken into when constructing the system.

Q. Are you planning to use this approach elsewhere in Japan or abroad? If so, where?

Kyocera TCL Solar plans to develop floating installations at 30 reservoirs in Japan, totalling approximately 60MW by the end of this fiscal year: March 31, 2015. We are currently looking into the possibility of expanding the floating solar business overseas.

Q. What technology vendors did you consider for this project and why did you select Ciel et Terre’s Hydrelio floating solar platforms?

We selected Ciel et Terre for their experience with megawatt-class large-scale floating projects. Ciet et Terre is a pioneer in this field, and no other vendors have a proven track record of completing such sizable installations.

Q. Are there any special permitting or environmental considerations you have to take into account, and if so how are you dealing with them?

Special permits are typically required, but vary depending on the municipality or region of installation. Environmental factors must also be taken into consideration, in particular that the equipment will not corrode and affect the water quality.

That is one reason why we have chosen Ciel et Terre's floating platforms, which are 100% recyclable, and made of high-density polyethylene that can withstand ultraviolet rays and corrosion.

Q. Do you see floating solar power as a potential growth market, and if so, why?

Due to limited land availability and the vast number of water reservoirs in Japan, we believe that there is great potential for floating solar plants.

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OP-ED

One of the driving factors feeding the floating or offshore solar farm concept is land availability. Asia is one region where sustainability is greatly needed across the energy and forest preservation sectors and this is where floating solar can help.

One such company that is taking this concept seriously is offshore advisory firm DNV, where researchers have developed a dynamic floating offshore solar field concept.

Dubbed SUNdy, the core feature of the concept is a hexagonal array which floats on the sea surface. A collection of these arrays, totalling 4,200 solar panels, forms a solar island the size of a large football stadium, capable of generating 2 MW of power. Multiple islands connected together make up a solar field of 50 MW or more, producing enough electricity for 30,000 people.

Bjørn Tore Markussen, Chief Operational Officer for DNV KEMA Energy & Sustainability Asia says renewable energy is becoming increasingly important in nations across the globe, including Asia.

“With such a readily available and abundant source [in Asia] that is rapidly approaching grid parity levels, it’s solar power that’s attracting a lot of interest in this part of the world,” says Markussen.

The SUNdy concept uses thin-film 560 W solar panels, which are flexible and lighter than the traditional rigid glass-based modules, allowing them to undulate with the ocean’s surface explains Sanjay Kuttan, Managing Director of the DNV Clean Technology Centre in Singapore.

“The key to creating an ocean-based structure of this size is the use of a tension-only design. Rather like a spider’s web, this dynamic, compliant structure yields to the waves, yet is capable of withstanding considerable external loads acting upon it,” he explains.

According to Dr Kuttan separating the solar arrays into prefabricated sections allows for large scale manufacturing and streamlined assembly offshore. The cable grid provides for maintenance access in the form of floating gangways. Below the surface, the shape of the island is maintained by the tensile forces from the lengthy spread mooring.

“The island has been optimised for solar capability and cabling efficiency,” adds Kevin Smith, Global Segment Director for DNV KEMA’s Renewable Energy Services.

He explains in more detail: “The solar arrays are divided into electrical zones feeding electricity produced into two main switches collecting the power for voltage step up at a central transformer (2MVA 480/34.5kV). From the offshore solar farm’s central island, 30kV electrical transmission lines connect, tying other islands in series to form a close loop and continue to the electrical sub-station onshore for grid connection.”

Offshore solar: the next frontier?

While solar power has experienced a boom in recent years with many experts and analysts expecting a tapering off of growth projections for new installations in 2015, we could see solar take a new shape over the next few years, literally, in the form of offshore solar plants.

Undoubtedly, there will be opposition or serious questioning towards such concepts, either from marine environmentalists or those with little endeavours to take their panels offshore. But the concept is already being proven, by companies such as Ciel et Terre. This niche market could prove to be more universally accepted and adapted following Kyocera’s plant completion, alongside others.

PV Insider will watch this space with interest.