Original title: Solar panels 'grow' from the seabed — China releases its first pile-foundation fixed offshore photovoltaic project

Having withstood the severe tests of fierce winds and torrential rain, the pile-foundation fixed offshore photovoltaic projects in the coastal waters off Haiyang City and Wendeng District of Weihai City, Shandong Province, have exceeded expectations in terms of anti-corrosion, wind resistance, wave resistance and system stability. This means that the results of China's first pile-foundation fixed offshore photovoltaic demonstration project have achieved phased success. The above results were released in Jinan recently. Experts believe that, given that there are no mature offshore photovoltaic development models or successful experiences at home or abroad, the success of this project marks a breakthrough in China in the relevant fields, achieving something 'from nothing to something'.

It is understood that offshore photovoltaics are mainly divided into two major categories: pile-foundation fixed and floating. At the current stage, offshore photovoltaics are dominated by the pile-foundation type, and the construction of offshore floating power stations is still in the process of going from 0 to 1. The so-called pile-foundation fixed type can be simply understood as photovoltaic 'legs' being deeply embedded in the sandstone layer below sea level.

The pile-foundation fixed offshore photovoltaic project in the coastal waters off Haiyang City, Shandong Province.

Taking advantage of calm seas, the reporter visited the pile-foundation fixed offshore photovoltaic project in the coastal waters off Haiyang City, Shandong Province. Xing Fu, Party Secretary, Executive Director and General Manager of State Power Investment Corporation Shandong Energy Development Co., Ltd., told the reporter: 'This site is about 6.5 kilometers from land, with an average water depth of 7 meters. It is the first pile-foundation fixed offshore photovoltaic project in China built in open offshore waters.'

'The photovoltaic industry is not a new industry, but offshore photovoltaics has only just emerged.' Yang Suchun, a technical researcher at Tianjin Port and Waterway Engineering Co., Ltd., said that some regions in China have carried out a series of explorations in offshore photovoltaics, but most are concentrated in water areas such as tidal flats, intertidal zones and salt fields. He stressed that, compared with onshore photovoltaics, offshore photovoltaics has natural environmental advantages: the water surface is open with no obstructions, and sunshine is longer and fully utilized, which can significantly increase power generation.

However, installing photovoltaic projects in offshore waters is not easy. Xing Fu mentioned the harsh offshore environment, such as high salt fog, high salinity and alkalinity, strong ultraviolet radiation, extreme temperature changes, alternating wet and dry conditions, biological attachment, as well as complex seabed geology and unstable foundations, all of which constantly test photovoltaic modules.

Yang Suchun told the reporter that, unlike onshore photovoltaics, offshore photovoltaic power stations are installed using a 'pre-installation on land + offshore hoisting' model. Simply put, most of the installation is completed on land, then transported directly to the offshore site and 'pressed' into the underwater rock and soil.

But this modular approach brings two major challenges: on the one hand, installation costs are higher, so more efficient modules are needed to reduce costs; on the other hand, this installation method also places extremely high demands on the modules' resistance to micro-cracks.

However, today, the implementation and stable operation of the two major pile-foundation fixed offshore photovoltaic projects in Haiyang City and Wendeng District of Weihai City mean that all these problems have been solved.

Yang Suchun said that the photovoltaic panel modules above sea level are formed on land and then transported directly to the offshore site for installation. Above sea level, wave heights sometimes reach as high as 6.5 meters; below sea level, the pile length is nearly 30 meters. During installation, the modules first pass through 9 meters of seawater, then through a 9-meter-deep thick silt layer, then through a 2-meter-deep silty soil layer, until they are inserted into sandstone 23 meters below sea level. To this end, the R&D team used pipe piles with a length of 32 meters and a diameter of 70 centimeters, applied steel pile shoes at the bottom of the sandstone to increase strength and durability, and added anti-rust and anti-corrosion measures.

The reporter found that the above offshore photovoltaic modules are covered with sensors. With the help of internet technology, all real-time data will be summarized and fed back to provide reference for decision-making.

The offshore photovoltaic project, supported by science and technology, has withstood the test. From April to September this year, Force 8 gales struck the project, but all its monitoring data remained normal.

The first pile-foundation fixed offshore photovoltaic project is inspiring. Li Xuedong, Chief International Cooperation Coordinator of State Power Investment Corporation, said that this pile-foundation fixed offshore photovoltaic demonstration project integrated, optimized and compared multiple technologies, further verifying the reliability and durability of photovoltaic power generation technology in complex marine environments.

'Facts have proven that offshore photovoltaic development has great potential, high comprehensive benefits and is eco-friendly.' Hu Bo, Deputy Director of the Shandong Provincial Development and Reform Commission and Director of the Shandong Provincial Energy Administration, said that developing offshore photovoltaics is not only an effective way to break through land constraints and expand the development space for new energy, but also a powerful lever for developing the ocean and cultivating strategic emerging industries.