header image: Sungrow - Coal mining subsidence area of Huainan City (#1)

by Mina Mesbahi & Saori Minamino

More and more countries, from Japan and beyond, are chasing the idea of placing photovoltaics on massive bodies of water. These so called ‘floating solar systems’ also known as ‘floatovoltaics’ can indeed be a plausible solution in situations with limited roof and/or ground space.

But is this cutting-edge Sun-sucking tech becoming a new standard to put underutilised water and rays of sunshine to good use? Is floating PV still considered merely a viable niche or has it transcended beyond into a growing market? Where are these floatovoltaics mostly located? What is their size and available capacity? This article is concerned with providing answers to these questions by means of identifying the Top 70 Floating Solar PV Plants globally and some additional insights to better navigate the foreign waters of floatovoltaics.


Quick statistics :

  • The cumulative capacity of the updated top 70 floating plants has more than doubled in comparison with last year's

  • The largest and smallest floating plants account for a capacity of 40 MW and 696 kW respectively

  • One primary developer has been involved in bringing more than half of these floatovoltaics online

  • 54 of these plants are located in one solitary country


Umenoki Solar Plant (#4) - Image: Ciel e Terre

Umenoki Solar Plant (#4) - Image: Ciel e Terre


Top 10 Floating Solar PV Plants

Rank Size (kW) Name of reservior (lake) / Name of Plant Country City/Province Operating from System Provider
1 40.000 Coal mining subsidence area of Huainan City China ** ** **
2 20.000 Coal mining subsidence area of Huainan City China ** ** **
3 9.982 Pei County China ** ** **
4 7.550 Umenoki Japan ** ** **
5 6.776 Jining GCL China ** ** **
6 6.338 Queen Elizabeth II Reservoir UK ** ** **
7 3.000 Cheongpung Lake South Korea ** ** **
8 3.000 Otae Province South Korea ** ** **
9 3.000 Jipyeong Province South Korea ** ** **
10 2.991 Godley Reservoir Floating Solar PV UK ** ** **

** Check full overview for all additional data


Capacity

The top 70 floating solar plants accumulatively hold 198 MW in capacity, which is more than twice the capacity in 2016. Currently, the largest and smallest plant account for a capacity of 40 MW and 696 KW respectively. Last year, the biggest floating plant had a capacity of 20 MW and smallest of the top 70 had a capacity of 5 KW, which pales in comparison with 2017. Therefore, there has been evidently a substantial growth in the available PV capacity amongst the floatovoltaics in both sides of the spectrum. Coal mining subsidence area of Huainan City in China has held the highest capacity in two consecutive years. Moreover, this very area has tripled its capacity in a mere span of one year and is home to both largest and second largest floating plant. The two smallest plants also happen to be both located in Japan; overall the list is somewhat geographically-concentrated and shows less variety when compared with 2016.


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Location 

While arrays of photovoltaic panels can be theoretically placed on floating bodies of water anywhere in the world, approximately 80% of the top 70 floating solar PV plants are located in the country of Japan, the total capacity of which represents more than 47% of the list’s cumulative capacity. Thus, Japan is unequivocally leading the world of floatovoltaics by a landslide. The evident dominance of Japan can be explained by virtue of the generous feed-in tariffs as well as a lack of suitable land propelling developers to identify creative solutions off-land. The second country with the biggest margin is South Korea harbouring 8% of the top 70 solar PV plants in the world, whereas in 2016 the UK was the second leading country. China, UK, Taiwan and Belgium comprise the home for the rest of top 70 floating solar PV plants.


Coal mining subsidence area of Huainan City (#1)

Coal mining subsidence area of Huainan City (#1)

Queen Elizabeth II Reservoir (#6) - Image: Ciel e Terre

Queen Elizabeth II Reservoir (#6) - Image: Ciel e Terre


The rise & rise of floatovoltaics

According to the World Economic Forum, floatovoltaics have been in use for a little over a decade. Nonetheless, they were very small in numbers and limited in terms of geographical location. Presently, floating solar installations can be found all across the globe and have significantly grown in numbers as well as capacity. Over the last three years, more than 100 plants have begun to operate, whereas a mere number of three floating solar plants had ever gone online prior to 2014. In June of 2017, Ciel & Terre, a France-based floating PV specialist, started construction on the world’s largest plant with a capacity of 70 MW.  This plant is located in China’s Anhui Province for China Energy Conservation and Environmental Protection Group (CECEP), and expected to be operational in 2018. All in all, the trajectory of China’s renewable energy is taking a leap forward as they put the brakes on fossil fuel consumption and carry the torch for sun-powered fuel.


Water meets solar & the environmental aftermath

As solar energy becomes more affordable and prevalent around the globe, new technologies and methods of installations are materialising. Particularly, floatovoltaics have transformed into a growing market and essentially become an alternative to conventional solar. Floating solar arrays are typically installed on impounded bodies of water, whether man-made or natural. Floatovoltaics can be installed by either private or public entities operating in virtually in any industry. Nevertheless, they are specifically beneficial for water-intensive industries. Moreover, companies concerned about conserving land, for instance agricultural companies, floating systems can be the ideal mode of energy production for them.

In addition, there has been some concerns regarding the potential negative impacts of floatovoltaics on wildlife and the ecosystem. According to Ciel & Terre, their floating systems are not deleterious to the environment but to the contrary, they are quite favourable for the environment. The installation of floats can reduce the algae growth, whose presence is essential to maintain the quality of the water. However, too much algae can have the exact opposite impact. Ciel & Terre often installs their plants on artificial ponds mostly with existing ecosystems. Their aim is to strike the  ideal balance between maintaining water quality to preserve it and to provide a suitable habitat for the plants as well as animals. For instance, for one of the company’s projects in the U.S. (Kunde), aerators can be combined with the floating PV mixing the water and consequently providing better oxygenation to the pond. Another potential concern would be the coverage ratio defined as the percentage of the water surface covered by floating solar arrays. There a number of factors to consider when deciding on a plausible coverage ratio including site conditions, temperature, wind, exposition, etc. The coverage ratio of Ciel & Terre’s projects falls between 30%-60% on average. 70% would represent a significant coverage ratio and a larger ratio would also depend on the clients’ needs. Moreover, the company has never, thus far, been informed of any actual damages regarding the wildlife as a result of light reflection or otherwise.   


Agongdian Reservoir (#20) - Image: Ciel e Terre

Agongdian Reservoir (#20) - Image: Ciel e Terre

Kawarayama Ike (#40) - Image: Ciel e Terre

Kawarayama Ike (#40) - Image: Ciel e Terre


Operation & Maintenance

Camille Marliere from Ciel & Terre states that there are not any striking differences between ground and water as far as the installation is concerned. In fact, contrary to popular belief, floating PV systems do not represent greater but different challenges and in some instances, do indeed face fewer barriers. In case of big reservoirs, a boat is required to provide access to the platform. Therefore, Ciel & Terre creates float paths to facilitate the accessibility and hence the maintenance of these plants. For small reservoirs, the company installs a safe path with floats from the shores to the platform, which are very safe for the workers as the floating platform is highly stable given that it is designed based on buoyancy principles and maintenance constraints. As per any other energy system, there are costs associated with proper maintenance of floatovoltaics. In order to optimise these costs, Ciel & Terre considers the maintenance constraints and correspondingly sets forth a system design with the right equilibrium between safe and cost-effective. As an example, their system can be supplied with additional ease of maintenance depending on the market needs primarily by virtue of row maintenance of the floats. Marliere finishes by saying that- “We have designed and optimised our Hydrelio solution- and we always continue to optimise our solutions, as we begin to complete the range of Hydrelio product- to enable an easy & safe maintenance of the plants”.


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