A consortium led by Dutch research institute TNO has launched a study into flexible floating solar energy systems as a potentially viable technology for offshore floating solar farms.

The system, consisting of flexible floating units with flexible solar panels mounted on them, has been installed recently in the Oostvoornse Meer lake, near the Maasvlakte – a harbour and industrial area close to Rotterdam.

The pilot, which will run until summer 2022, will explore using this technology as a possible route in the creation of economically viable offshore photovoltaic (PV) systems.

In this study, the consortium is looking at various aspects, such as the energy yield of the flexible solar panels, behaviour of the floating units when faced by waves and strong winds, growth of organic material on the units, and economic viability.

Solar on water is expected to make a key contribution to the energy transition, according to TNO, as solar energy capacity of 200GWp is predicted for the Netherlands in 2050, including 25GWp of solar panels on inland waters, and 45GWp installed offshore solar energy.

Wim Soppe, researcher at TNO, said: “Solar power at sea or offshore PV does not yet actually exist. It is technically very challenging to install large floating systems with solar panels at sea and keep them operational for decades.

“In addition, due to the expense of material used for heavy, rigid floats, it is often difficult to make these systems economically viable. This new concept requires a lot less material and we therefore have high hopes that it will turn out to be a lot cheaper”.

Bending with waves for cheaper solar power

The concept consists of two floats measuring 7 by 13 metres topped by 20kWp of solar panels. What makes the structure special is that both the solar panels and the floats were made of a flexible material (thin-film PV) developed by the consortium.

This application enables the floats and the panels to bend with the movement of the waves. They offer less resistance to the waves, so that the floats and the anchoring can be lighter and can therefore be produced more cheaply than with rigid floats, according to TNO.

The project is being developed by a broad consortium in which TNO is partnered by Bluewater Energy Services, Genap, Marin, Endures, and Avans University of Applied Sciences.

Bluewater is responsible for anchoring the system; Genap developed the flexible floats; Marin tested the hydrodynamic properties of the floats in its model test basin; Endures is studying organic growth on the panels and drivers, and how to prevent it; and Avans is developing maintenance and recycling strategies for this concept.

After completing this project, the next step is to build and install a system on the North Sea. The initial aim is to use the system to test an efficient installation and maintenance methods that the consortium is already developing.

This is important because installing and maintaining floating systems at sea is considerably harder than on land, which can make it a lot more expensive, TNO said.

The next ambition is to build a commercial system of 1-5MWp around 2024, which can be installed and electrically linked up with one of the new wind parks on the North Sea.

Because solar and wind energy production have little overlap in time, there is no need to run additional cables to land, according to TNO.