3. Design of supporting part

(1) Selection of solar bracket foundation

It mainly considers meeting the calculation requirements of foundation bearing capacity, foundation overturning resistance, pulling resistance, and slip resistance to ensure the stability of the superstructure.

At present, China mainly adopts reinforced concrete independent foundation, reinforced concrete strip foundation, prestressed cement pipe pile foundation, etc. Reinforced concrete foundation is mainly used in places with relatively good address conditions, such as “agricultural light complementarity”, “animal light complementarity”, etc. The main advantages of reinforced concrete cast-in-situ foundation are that the construction difficulty is small, the positioning of the foundation plane and the top elevation of the foundation are easy to control and resist overturning and slip, the overall effect is good, the overall visual sense after the completion of the power station is good, and the accuracy of the best inclination angle can be guaranteed. The disadvantages are that the construction period is long, the damage to the ground is large, and the amount of earthwork excavation, backfilling, formwork configuration, rolling steel bars and so on is large; Prestressed cement pipe pile foundation is mainly used in places with relatively harsh geological conditions, such as “fishery and light complementarity”, along the beach mudflat, etc. The main characteristics of the prestressed cement pipe pile foundation are prefabricated finished products, fast construction speed, less damage to the ground, and relatively small engineering quantity. The disadvantage is that the technical and experience requirements of the pile driving operators are high, and the construction is relatively difficult.

The positioning of the foundation plane and the elevation of the top layer of the foundation are not easy to control, and the secondary reverse work is added after lifting and unloading, which increases the workload and difficulty of the installation and construction adjustment of the later support, and it is difficult to enter the pile in the gravel formation, easy to eccentric or break the pile, and it is not suitable to use. The two schemes have obvious advantages and disadvantages of interchangeability, and should be comprehensively judged based on local geological conditions and engineering characteristics.

According to the local geological conditions, the degree of corrosion of groundwater to the reinforced concrete structure is judged. For weakly corroded areas, measures such as applying anti-corrosion coatings on the surface below the groundwater table are adopted; For highly corrosive areas, anti-sulfate Portland cement, anti-sulfate admixtures, steel bar rust inhibitors, mineral admixtures, and anti-corrosion coatings are applied to the surface below the groundwater table.

(2) Selection of bracket system

At present, domestic photovoltaic power plants mainly adopt the best inclination fixed type, horizontal single-axis tracking type, oblique single-axis tracking type and dual-axis tracking type and other bracket systems. The fixed mounting bracket has relatively low cost, simple manufacturing process, short production cycle, low installation difficulty, and the bracket system is basically maintenance-free. The fixed bracket system has a relatively small footprint and is virtually maintenance-free. Fixed bracket systems have a relatively small footprint; The automatic tracking type has a high cost, a high manufacturing process, the tracking motor is easily damaged, and the operation is unstable, especially the maintenance and repair volume of places with high humidity. In order to avoid occlusion, the distance between the front and rear left and right of the tracking bracket system array is large, which increases the floor space by about 50% and increases the investment cost, but the power generation is greatly improved compared with the best inclination fixed type, and the theoretical calculation is about 20%~30%. At present, the logic of the tracking bracket system that has been put into operation somewhere is simpler and more reliable, which is worth learning. Therefore, comprehensive analysis should be made from the aspects of terrain conditions, floor space, operational reliability, equipment price, maintenance costs after completion, failure rate and power generation benefits. It is not recommended to use automatic tracking system for places with high humidity such as “fishery and light complementarity” and beach mudflats, because the foundation of the automatic tracking system bracket is mainly a reinforced concrete strip foundation, which is not easy to construct on fish ponds, lotus ponds and tidal flats, and the humidity is large, the motor is easy to be burned by moisture, and maintenance is inconvenient.

To be continued…