In early November 2023, the world's largest Ocean photovoltaic project-Shandong Dongying Kenli 1 million kilowatt offshore photovoltaic project has officially started construction. The project is located in the waters of Laizhou Bay, Dongying City. After completion, the annual power generation is expected to be 1.78 billion kilowatt hours.
On December 26, my country's first large-scale ocean pile-based fixed offshore photovoltaic project, China General Nuclear Power Group Co., Ltd. Yantai Zhaoyuan 400 MW offshore photovoltaic project, also officially started construction. The project is also located in the waters of Laizhou Bay, with a total planned area of approximately 6.44 square kilometers, and consists of 121 photovoltaic sub-arrays. It is the deepest, most difficult to construct, and the most complex development condition among the first ten offshore photovoltaic project sites in Shandong Province. of site. After completion, the average annual power generation is expected to be 690 million kilowatt hours.
However, moving from "land photovoltaic" to "ocean photovoltaic" is far more than just "moving" photovoltaic power plants from land to sea. Experts said that currently there are challenges in all stages of offshore photovoltaic projects such as preliminary procedures, project construction, and later operation and maintenance management.
Especially in terms of equipment and construction, there are many challenges.
At present, there are two types of floating photovoltaics, one is the fixed type on pile foundation and the other is the floating type on the sea.
Large-scale ocean photovoltaic projects are currently mainly based on fixed pile foundations on coastal beaches or intertidal zones. Use a pile driver to drive reinforced concrete pipe piles with a diameter of 30-50 cm into the water, similar to foundations, and then install corrosion-resistant metal photovoltaic brackets on the piles. Since pile driving can only be carried out within a water depth of 5 meters, where there are no geological hazards and small water level changes, pile-based fixed power stations can usually only be installed on tidal flats and intertidal zones. In the long run, stationary applications have limited scope.
The country's largest coastal tidal fishery and light complementary photovoltaic project, which will be put into operation in 2021, the Xiangshan Changtu tidal flat project is located in the tidal flat area of Xiangshan County. It has 630,000 photovoltaic panels and generates an annual power generation of up to 350 million KW.
The construction of pile-based photovoltaics is quite difficult. Because the tidal flat area is covered with ocean at high tide and filled with mud at low tide, transport ships often run aground halfway. The seemingly simple transportation of pipe piles is actually very difficult.
In addition, because tidal flat photovoltaics are located at sea, the environment is humid and salty, and the metal supports are easily corroded. There are many typhoons in the coastal area and the impact is large, which can easily have a serious impact on the safe and stable operation of the photovoltaic area. It is often necessary to build additional wave-absorbing walls to alleviate the erosion of photovoltaic power stations by waves.
Floating photovoltaic systems use floating bodies, moorings, and anchors instead of land-based piles and supports. The floating body component floats on the water surface and is moored and anchored within a fixed range. Compared with fixed pile-based floating photovoltaics, floating photovoltaics face a more complex and changeable environment. The weight, area, draft, etc. of the component floating body need to consider the overall importance of the system and the weight of marine attachments that are more than 25 years old. At the same time, the components need to fit closely with the floating body to ensure resistance to the impact of sea wind and waves.
