When it comes to solar energy, I believe you are no stranger. As an emerging renewable clean energy, it has been applied to all aspects of our life. Solar calculators, solar water heaters, solar power stations and even street lamps on the road are powered by solar energy. But have you ever seen a solar power station on water?
This kind of water solar power station not only exists, but also the world’s largest water solar power station is in China.
The water solar power station has a total installed capacity of 40 MW. It is divided into 16 power generation units. It is the largest water floating photovoltaic power generation project in the world. It was originally a “big puddle” with a depth of more than 10 meters and an area of more than 6000 mu formed by coal mining subsidence. After the power station is completed, the “big puddle” has become a “base”, and the sense of science and technology burst in an instant!
On the wide water surface, there are pieces of solar panels floating on the water surface. They are supported by gray plastic floating tanks. There are thousands of engineering piles made of reinforced concrete under the floating tanks. The position of each engineering pile is designed and positioned by GPS, and then the diameter and length of the engineering pile are determined according to the actual situation of the whole underwater and the weight of the floating body.
There is almost no error in the middle. Thick cables are used to connect the piles, floating tanks are placed on them, and steel cables are used to connect the floating tanks in sequence. Solar panels are laid on them, and finally a spectacular photovoltaic power generation array is formed.
It is said that these square arrays are very strong and can resist force 8 winds. The design service life is 25 years.
What is the principle of such a magnificent “big production” and what is special about this design? Let’s explore it.
What is the difference between water solar power station and land solar power station?
The composition of water photovoltaic power station mainly includes two parts: photovoltaic system and surface auxiliary equipment.
The hardware components of the surface photovoltaic power station are mainly solar panels, combiner boxes, inverters, transformers, collector lines, polyethylene floating platforms, etc. At present, the water surface used is mainly ponds, small lakes, reservoirs, reservoirs, etc.
According to the support mode of photovoltaic modules, water photovoltaic power stations are mainly divided into two application forms: pile foundation fixation and water surface floating. The selection of its specific form is generally preliminarily determined by the water depth. Pile foundation fixation can be adopted in shallow water area (water depth is less than 3m), and surface floating can be adopted in deep water area (water depth is greater than 3m, runoff is stable, water level change is generally less than 6m, and water depth is basically the same).
In addition, for unstable coal mining subsidence areas, floating mode can also be adopted in principle, mainly “fixed piling + fixed support” and supplemented by “fixed piling + tracking support”. The floating mode on the water surface can be divided into two forms: floating pipe type and pontoon type.
Compared with land-based photovoltaic power stations, the cable design and laying of water-based photovoltaic power stations are also special.
In order to reduce line loss, cables with different cross-sectional areas need to be selected according to the distance from the confluence point. At the same time, in order to cope with the change of water level, the cable length should be increased appropriately according to the actual situation.
In addition, for cable tray, considering the driving, maintenance, operation and maintenance of fishing boats, long-span tray is mostly used, and the tray can generally be supported by triangular support brackets. Japan’s floating project also uses closed resin tubes to float on the water.
Another big problem of water-based photovoltaic power station is that the site environment is humid, salt fog corrosion and strong wind and waves, so the equipment needs to be waterproof, corrosion-resistant and aging resistant.
For solar panels, double glass solar panels with better reliability (lower moisture transmittance) or single glass frame solar panels with resistance to potential induced attenuation and salt spray corrosion shall be selected; The floating body shall be able to resist UV, corrosion, frost expansion, wind and wave, long service life, etc; Supports and bridges shall also have the ability of corrosion resistance and high strength; Electrical equipment shall have IP67 dust and water proof capacity and corrosion resistance.
What are the advantages of building solar power plants on water?
Since there are so many challenges for water photovoltaic power plants, why should they be built on the water? This is because it has incomparable advantages over photovoltaic power stations on the road.
- Save resources
The water photovoltaic power generation project does not need to build supports or dig cable trenches, which greatly reduces the ground excavation. The covered solar panels can also slow down the water evaporation rate and protect water resources.
In some areas with limited land resources and great difficulty in land development, the development of water photovoltaic projects is a good choice, which opens up a new road for the application of photovoltaic power generation.
- Efficient power generation
The terrain of the water surface is relatively open, with good reflective effect. It can also effectively reduce the blocking of trees and buildings to the sun, so that the sun irradiation area is uniform and the illumination time is long.
In addition, water can cool the solar panel, which can maintain high power generation efficiency under the same conditions. According to the survey, if the temperature of the solar panel is reduced by 1 ℃, the output power can be increased by 0.5%, especially when the temperature is high in summer, the power generation can be 10% ~ 15% higher than that of the ground or roof power stations in the same area.
- Low cost
The surface floating photovoltaic power station has integrity, which is convenient for the installation and operation of solar tracking system, and greatly reduces the high cost caused by the installation of biaxial tracking system for each solar panel.
The floating platform can be made of bamboo raft with special waterproof treatment, which can not only save cost, but also be recycled for many times. In addition, the cost of land accounts for about 3% of the cost of ground photovoltaic power stations, and there is no land tax on water.
- Convenient maintenance
The materials selected for water photovoltaic power generation must meet the highest waterproof requirements. Compared with ground photovoltaic, cleaning has less damage to the power generation efficiency of solar panels, and the commissioning of the overall system is more convenient.
- Tourism benefits
The water photovoltaic power station can transform the originally insignificant lake into a unique scenic spot, increase the ornamental nature of the water landscape and bring tourism benefits.
In addition, it can also synchronize aquaculture. In addition, the construction of aquatic photovoltaic power stations in reservoirs or fish ponds of aquaculture industry can create a better incubation environment for fish, control algae growth and improve the output of aquatic products.
