Floating solar islands designed to power crowded cities

Not to be confused with what could be the biggest storm ever to hit the United States, SUNdy – a large-scale offshore solar farm concept by global consultancy and certification firm DNV – was unveiled at Singapore International Energy Week on Thursday last week.

The core feature of the floating solar concept is a hexagonal array of 4,200 solar panels – roughly the size of a football pitch – which floats on the sea’s surface. The ‘solar island’ would be capable of generating 2MW of power, with multiple islands joined together to create an offshore solar field of 50MW or more, producing enough electricity for around 30,000 people.

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

Sanjay Kuttan, managing director of the DNV Clean Technology Centre in Singapore says SUNdy’s thin-film 560W solar panels are flexible and lighter most silicon-based modules, allowing them to undulate with the ocean’s surface. “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.”

Dividing solar arrays into prefabricated sections, says Kuttan, allows for large-scale manufacturing and streamlined offshore assembly. Floating gangways for maintenance access while, below the surface, the island is held together by lengthy spread mooring.

Bjørn Tore Markussen, Chief Operations Officer for DNV KEMA Energy & Sustainability in Asia, says the company firmly believes that the SUNdy floating solar field concept offers “sound and sustainable development prospects.” Particularly so in Asia, he says, “and the congested coastal megacities where there’s limited opportunity for rooftop solar power and urban areas which command premium prices for large-scale mounted solar production.”