Floating solar panels are on the rise—but Denmark has not even started on them

15. december 2021 kl. 11:34
Floating solar panels are on the rise—but Denmark has not even started on them
This facility is part of the Far Niente Winery in Napa Valley, California. The solar panels are located on the vineyard’s irrigation lake. Illustration: SPG Solar / Wikimedia Commons.
Solar panels floating on water could definitely contribute to the green transition, but not a single such project has been started in Denmark—despite obvious possibilities.
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If you have taken a car trip through Denmark in the last five years, you have definitely come across one or more solar parks. They are now popping up along the Danish fields as a part of the green transition. During the same trip, you have most likely also driven past larger bodies of water—lakes, reservoirs, streams. If you have driven far enough, you may have reached the sea.

Can solar panels be installed there—on the water?

A number of companies and experts are convinced that they can, and the development of floating solar panels is already underway outside the Danish borders.

A rising industry

The International Energy Agency (IEA) prepared a report on new photovoltaic energy technologies earlier this year, in which floating solar panels are described. They write that the market has grown rapidly: “... from 2 MWp installed in 2011 to an estimated 2.2 GWp at the end of 2019, and this fast growth of the sector is expected to continue,” the report reads.

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A simple illustration of what a floating photovoltaic system could look like. The challenge is getting the solar panels anchored well enough to the bottom so that they stay where they need to be. The solar panels themselves do not differ much from normal solar panels. Illustration: Solar Energy Research Institute of Singapore (SERIS).

At the same time, the global energy research and consultancy firm Wood Mackenzie writes that global demand for floating solar panels will increase by an average of 22 percent every year between 2019 and 2024.

This development is very similar to the projected growth of ordinary solar panels.

In addition, one could recently read about the opening of the world’s largest floating solar power farm in Thailand with an output of 45 MWp. A record that will not stand very long.

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This summer, the Singaporean company Sunseap Group secured a contract which commits the company to building a huge floating solar park off the Indonesian island of Batam. The project will be able to deliver an output of 2.2 GWp and should be completed in 2024.

“As technology has evolved, we have seen more and larger projects emerge,” Stanislas Merlet says. He is a senior consultant on floating solar panels at the Norwegian consulting company Multiconsult and is in the process of writing a PhD on the topic of floating solar panels at the Norwegian University of Science and Technology in Trondheim.

In addition to the examples from Asia, he mentions several new projects in Africa and is convinced that the development will continue.

Per Lindberg shares the same optimism. He is the owner of the company Sunlit Sea, which manufactures a very special kind of floating solar panels, and has a PhD in metal oxides in solar cells from the University of Oslo.

“The future of floating solar panels is very promising. Much of the infrastructure is already there, and we already know how to develop such projects,” he says.

However, he sees a challenge in getting the legislation in place, as well as getting the components used in the technology verified and certified.

Legislative wording puts a block on projects in Denmark

Inadvertently, the Norwegian researcher hits the nail on the head, as legislation has been a problem for the development of this technology in Denmark.

To be allowed to build renewable energy systems at sea, one must either win a tender from the state or apply through the open door scheme. The problem is that the scheme did not allow applying for projects like floating solar panels. This was due to the legislative wording of the Renewable Energy Act, which provided “access to utilize energy from water and wind at sea”. Sun was not mentioned.

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It is now being changed so that the scheme is made “technology neutral”—the change is expected to take effect next summer.

“The open door scheme has previously blocked floating solar due to the specific wording, but even though it’s now being changed, the technology is currently not widespread in Denmark. For now,” says Thomas Aarestrup Jepsen, director of the industry organization Dansk Solkraft.

He adds that the developments in the technology are monitored, and that he is generally in favour of it. However, the big question is where to build floating solar panels in Denmark.

“Abroad, it has been done in bays, large gravel pits, or fjords where there is relatively calm water. We just don’t have the same conditions in Denmark, and that causes some technical challenges,” Thomas Aarestrup Jepsen says. “I can’t immediately think of a lot of large inland lakes that could be used here,” he adds.

This challenge is not made easier by another piece of legislation. In Denmark, lakes larger than 100 m2 are protected under the Nature Conservation Act §3—another complication in the domestic development of floating solar panels.

Why use floating solar panels?

Solar panels on water are not so easy to introduce to Denmark, and it can seem like a futile project. But elsewhere in the world, it makes perfect sense, according to PhD student Stanislas Merlet.

“The obvious purpose of floating solar panels is to save space. In Japan, the technology was adopted a few years ago in an attempt to tackle the problem of sparse agricultural land,” he says.

The other big advantages are that the water can function as natural cooling, and that you do not have to worry as much about trees or nearby buildings causing shade over solar panels or dust particles settling on top of the units.

Finally, Stanislas Merlet points out that over half of the Earth’s population lives near coasts, so it is only logical to base solar energy there..

Saltwater is not the biggest problem

Building solar panels on water involves difficulties not found on land. The immediate issue is how to ensure the survival of a solar panel in such a hostile environment. However, neither Stanislas Merlet nor the owner of Sunlit Sea Per Lindberg are concerned.

“Saltwater is obviously a challenge, but it’s not the biggest one. Wind and waves create constant movement that eats away at the materials. The solution is a good engineering design with solid anchoring and a good floating structure made of carefully selected materials. One also needs to increase maintenance. We know how to do all this,” Stanislas Merlet says.

At Sunlit Sea, they take saltwater seriously, but they also do not think that it represents the biggest challenge. The biggest challenge is how to anchor the solar panels to the bottom so that they are not torn loose.

“The challenge with larger matrices is that they tend to collapse when there are strong winds, tidal currents, and waves. That’s why you have to distribute the power over the entire matrix,” says Per Lindberg.

His company has solved this by making a system that is built around a standard frame, which is very similar to other solar systems. This component is prefabricated and forms the basis of the entire system. If the Norwegian company was to put its solar panels out over violent waters, it could add extra modules that do not have solar panels on them, but are just floating panels that serve to absorb shock of the waves.

A technology we will surely see more of in Denmark

Most floating solar parks, says Stanislas Merlet, are located on freshwater areas used for industrial use, such as drinking water systems or irrigation systems. But the amount of such systems is limited in Denmark, and we do not have areas that can naturally protect the solar panels.

However, this does not mean that floating solar panels have no future in Denmark.

“I am sure that they will eventually come to Denmark. 100 percent. The prices of renewable energy, and solar panels in particular, continue to fall, and floating solar panels are on the rise elsewhere,” Stanislas Merlet says. “I don’t see why Denmark shouldn’t also use them in the future.”

Per Lindberg sees Copenhagen as an excellent example of a place where floating solar panels will fit perfectly into the cityscape.

“With all the development around Copenhagen, floating solar panels would fit in perfectly. They must be built in collaboration with the locals and the city planners, but floating solar panels don’t take up much vertical space, so they won’t disturb the view much,” he says.

There is also a certain degree of interest in floating solar panels in country. The company European Energy wanted to build a floating photovoltaic system in collaboration with the Vordingborg Port, but it was shot down in early 2021 due to conflict with the Harbour Act.

While European Energy was waiting for the decision in the Vordingborg project, they had apparently driven south over the Storstrøm Bridge. Quite a few kilometres south of Vordingborg, the solar panel company announced in the summer of 2020 that it would build a pilot facility in the Nørre Vedby gravel pit.

In a written response from Guldborgsund Municipality’s press department, however, the project is buried.

“There are currently no projects underway in our municipality in relation to solar panels on water,” the response reads.

Whether the change in the open door scheme can change that, only time will tell.

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