With the deepening of the "dual carbon" target, offshore photovoltaic solutions have become an important field for global new energy development due to their advantages of not occupying arable land, superior lighting conditions, and high power generation efficiency. According to industry professional institutions' calculations, the potential installed capacity of offshore photovoltaics worldwide is about 4 billion KW, and the theoretical installed capacity of offshore photovoltaics in China exceeds 100 million KW, with a very broad development prospect.
With the continuous support of national and local policies, the development and construction of domestic offshore photovoltaic projects have entered the stage of "accelerated landing". A number of landmark projects, such as CNNC Tianwan 2 million kilowatt mudflat photovoltaic demonstration project, Hebei Huadian Changli 310,000 kilowatt offshore photovoltaic pilot project, Guohua Investment Rudong 400,000 kilowatt photovoltaic project, CGN Yantai Zhaoyuan 400,000 kilowatt offshore photovoltaic project, have been intensively implemented.
At the same time, coastal provinces such as Jiangsu, Zhejiang, Hebei, and Shanghai have successively completed the allocation and certification of owners for offshore photovoltaic projects within their jurisdiction. According to the North Star Solar Photovoltaic Network, the currently planned scale of offshore photovoltaic solutions in China is close to 100 gigawatts, and offshore photovoltaic scenarios are steadily moving from the "pilot" stage to the "scale" stage.
However, it should be noted that the fixed pile foundation technology in mudflat and intertidal zones is still mainly used for the current domestic offshore photovoltaic systems. Although this type of technology is mature and reliable, it is highly dependent on nearshore shallow water resources. As the exploitable areas near the coast gradually become saturated, exploring deeper and farther waters has become an inevitable choice, and floating photovoltaic solutions are the key direction for expanding the incremental space of offshore photovoltaics.
Towards the deep sea, the bottleneck of floating photovoltaic technology is highlighted.
Although floating photovoltaic solutions are the core development direction of offshore photovoltaics in the future, their technological exploration is still in the "demonstration and verification stage", and multiple key technologies urgently need to make breakthroughs.
On the one hand, offshore photovoltaic solutions face harsh environments such as large waves, typhoons, sea ice, high salt spray, high humidity, and frequent temperature changes. Salt spray corrosion, seawater corrosion, and water vapor infiltration pose higher requirements for photovoltaic equipment. On the other hand, the existing floating photovoltaic systems have obvious shortcomings, and some photovoltaic products have been verified by multiple empirical projects in recent years, but they are still unable to fully meet the "large-scale, long-term stable" power generation needs of deep and distant seas.
Especially for the photovoltaic system as the core of floating photovoltaics, there are certain "shortcomings" in the mainstream blow molded floating body, film type, and high freeboard structures on the market.
Specifically, the blow-molded floating structure is made of polymer materials to form a closed float, which is then assembled into a floating platform through ear hooks. Although it has the advantages of light weight, low processing cost, and convenient installation, its disadvantages are also prominent: weak wave resistance, poor fatigue resistance of connecting parts, and easy failure under long-term wave cyclic loads. The system life is usually less than five years and is only suitable for enclosed waters with minimal wind and waves. It cannot meet the operational needs of open or semi-open waters and is difficult to adapt to deep and far sea scenarios.
Compared with the blow-molded floating structure, the thin film structure has been optimized and upgraded in terms of wave resistance. It consists of photovoltaic modules, water elastic flexible films, buoyancy rings, and damping lines. The photovoltaic modules are mounted on the flexible film, which not only improves power generation efficiency through water cooling effect, but also significantly enhances wave resistance compared to blow molded floats. In theory, it is closer to the operational needs of the deep sea. But this technology has a core flaw: it relies on the continuous pumping of water by the pumping pump to maintain system stability. Once the pumping pump fails, the entire system will lose balance, face the risk of damage, and have serious reliability risks, which cannot guarantee long-term stable operation.
Among the three mainstream structures, high freeboard structures are currently the most deeply explored direction for deep-sea environments. It elevates the photovoltaic modules to seven to ten meters above the water surface by adding a metal bracket, and combines it with a rigid frame to enhance wind and wave resistance, greatly improving its adaptability to harsh environments in deep seas and effectively addressing issues such as large waves and deep water levels. However, behind this "strong adaptability" is a very high cost, which makes it difficult to achieve large-scale promotion and contradicts the development needs of the industry to "reduce costs and increase efficiency". It is currently unable to support the large-scale development of deep-sea floating photovoltaic solutions.
These technical shortcomings have been more intuitively exposed in actual project verification: the Hainan Wanning offshore floating test site, which adopts a blow molded floating structure, was dismantled after only a few days of operation due to sea area approval issues, and the test data showed that its maximum wave height was only 1.5 meters, with severely inadequate wave resistance performance.
The Guoneng Dongtai 100kW offshore project, which adopts a membrane structure, experienced damage to the membrane and photovoltaic panels after two months of operation due to the lack of a pumping pump. Reliability issues became the core bottleneck for its promotion. The Shandong Huaneng Huanghai-1 project, which adopts a high freeboard structure, has achieved technological breakthroughs in offshore distance of 30 kilometers, water depth of 30 meters, and maximum wave height of ten meters, effectively avoiding waves on photovoltaic panels. However, due to the high support cost exceeding ten yuan/watt, it is difficult to break through the economic shortcomings and achieve large-scale replication.
Balancing performance and cost, a basalt bracket breaks through the impasse. When various technological routes are caught in the dilemma of either insufficient performance or high cost, the emergence of this Basalt offshore floating brackets provides a solution that balances performance and cost for offshore photovoltaic scenarios.
This floating photovoltaic mounting system is designed specifically for offshore environments. From material selection to structural design, it addresses the core pain points of poor corrosion resistance, weak wind and wave resistance, and high operation and maintenance costs in offshore photovoltaics. Through targeted technological innovation, it solves each problem one by one and accurately compensates for the performance shortcomings of traditional floating photovoltaic mounting systems.
Specifically, in terms of corrosion prevention and durability, which are the "primary challenges" of offshore photovoltaics, the reason why traditional brackets are difficult to apply for a long time at sea is that floating bodies and metal materials are susceptible to erosion from sea winds, waves, and marine microorganisms. Therefore, PE100 grade polyethylene round pipes in the floating body was adopted, and the material has been verified by 1840kWh/㎡ ultraviolet irradiation aging test. The yellowing index, tensile strength and other indicators meet the standards, and the design life can reach 25 years. The bracket uses basalt fiber composite profiles with a density of only 25% of steel, but a tensile strength four times that of ordinary steel, which not only reduces the weight of the structure but also avoids the risk of corrosion.
In terms of structural design, traditional brackets often focus on the stability of individual units, but overlook the "systematic damage" caused by wave impact forces. To this end, a circular structure is formed as a floating body through end-to-end hot melt welding in structural design. Circular design can play a wave dissipating role similar to a breakwater, reducing the direct impact of waves on components.
With the help of concentric multiple circular rings, peripheral loads (such as gravity, wind, and pressure) can be evenly transmitted to the rings, dispersing stress concentration phenomena and enhancing the overall structural deformation resistance and load-bearing efficiency. At the same time, the spoke type structure reduces unnecessary material usage through the design of "using tension instead of compression" and "using less to support more", significantly reducing self weight while ensuring strength. The components are installed on basalt fiber composite purlins, reducing the possibility of direct wave impact on the components.
The connection between the purlin and the floating body adopts a pin axis design, which allows the purlin to rotate and swing within a certain angle, effectively dispersing the stress concentration caused by wind and waves and avoiding structural fracture.
The anchoring system is the foundation of offshore photovoltaic brackets. Traditional anchoring systems often suffer from poor adaptability and susceptibility to damage due to insufficient consideration of the differences in the seabed environment. When designing the anchoring system, environmental conditions such as wind, waves, and water levels under extreme conditions are comprehensively considered, and users with solutions such as pile anchoring and sinking anchoring can be provided.
The supporting mooring line adopts a three-stage structure: a chain is used on the upper part to avoid UV aging problems with the plastic rope. The middle part adopts multi-layer woven polyester fiber rope to reduce weight and prevent twisting. Use the chain again at the bottom to resist the friction of seabed gravel. This layered design enables the anchoring system to adapt to changes in wind and waves while also ensuring long-term stable operation.
The design of convenient operation and maintenance is quite outstanding. The circular floating body itself is a circular operation and maintenance channel, which replaces a path of photovoltaic panels with grid panels in the radial direction to form a radial channel. Operation and maintenance personnel can easily reach any position of the array. If a single spoke or photovoltaic panel is damaged, only targeted replacement is needed, without the need for overall disassembly. Disassembling the photovoltaic panel only requires simple ladder fixtures and does not require complex equipment.
From the perspective of key performance parameters, the basalt bracket indeed exhibits excellent performance: the maximum circular diameter of a single bracket is 100 meters, the power of a single component is 720WP, the maximum number of installed components for a single bracket is 2000, the capacity of a single bracket is 1,440KW, the wind resistance is 50m/s, and the wave resistance is 4 meters high. All performance parameters are in a leading position in the industry.
