Swimming solar the renewables of the future

 By Amanda Saint

Large onshore solar farms have become a very familiar sight all around the world but offshore has largely been the domain of wind. Until now. Swimming solar farms are starting to spread into global waters…

(Cover photo by

At the start of this year construction began on what will be the world’s largest swimming solar farm to date, which is just outside Tokyo. Scheduled to go online in 2018, it will cover 180,000 m2 and have 51,000 floating solar panels. Constructed on the Yamakura Dam Reservoir, the swimming solar farm is a joint venture between Kyocera Corporation and Central Tokyo Leasing Corporation.

Once live, the farm will generate an estimated 16,170 megawatt hours (MWh) of electricity per year, which will be sufficient to power just under 5,000 households. It will also offset approximately 8,170 tons of CO2 emissions a year, which is the equivalent of consuming 19,000 barrels of oil.

This is the fourth floating solar farm Kyocera has installed in Japan, which is fast running out of spare land suitable for large-scale renewable energy constructions. All three previous swimming solar farms have gone live during 2015 and 2016 and are providing 5.2 MW of power between them.

Imagine by

Global swimming solar

Outside of Japan large scale offshore solar farm projects are starting to be seen in many countries. Currently holding the title of the world’s largest, until the new Tokyo project goes live, is the Thames Water swimming solar farm housed on a man-made lake just outside London, UK.

There are 23,000 floating panels covering just 6 percent of the lake. The electricity generated is used by Thames Water to power a water treatment plant that provides clean water to around 10 million local homes and businesses.

In India the state-run National Hydroelectric Power Corporation is planning to install a 600 MW swimming solar farm alongside its existing Koyna Hydroelectric project in Maharastra, which consists of four dams and the Shivasagar reservoir.

Australia’s first floating solar project went live in 2015 at a wastewater treatment plant in Jamestown, South Australia, and the panels float on one of the wastewater basins. This was the first stage of a project that will eventually cover five wastewater basins. The electricity generated is enough to power the plant. The company that installed them, Infratech Industries, claims that the floating farm generated up to 57 percent more energy than a rooftop solar system would and also helped to improve water quality and reduce evaporation, which is a big problem for the plant.

In Brazil the first floating solar power system went live this year at the Balbina Hydroelectric Power Plant (HPP) in the Amazon. The country has seen its HPP’s struggle to meet demand in recent years due to low rainfall. This is the first of many planned floating solar projects that will help to meet electricity demand and reduce evaporation in the reservoirs where the farms are located.

Imagine by

Is water the solar energy location of the future?

The future growth prospects of offshore solar seem pretty positive. The benefits of locating solar farms on water rather than land are many. First, and most obvious, is that land doesn’t have to be taken up with solar farm constructions, which is a real issue for many densely populated countries with little land to spare for large scale renewable energy utilities.

Secondly, as these projects here have shown, the reservoirs and wastewater treatment centers are already there with the water ready and waiting for the solar panels to be installed. The panels slow down water evaporation, which is very important in countries where water is already scarce, and they help prevent algae growth. The water also works to keep the panels cool, making them work more efficiently.

What are the downsides? So far, the process of exporting the energy to shore has not been significantly more complex or expensive than onshore solar farms. Maintenance could be the only slight stumbling block as it tends to be a lot cheaper and easier to drive then walk to a panel located in a field when it needs fixing, rather than getting on a boat and heading out on a reservoir.

But with analysts predicting that the cost of solar panels will fall by 40 percent by 2020, offshore solar farms may become a much more viable solution than their onshore peers.

SEE MORE: Solar’s window of opportunity by RP Siegel

about the author
Amanda Saint
Journalist and content writer, specialised in engineering and technology with a focus on environmental sustainability, urbanisation and biotechnology.