1. Introduction:

Ground screw mounting structure is suitable for all large solar photovoltaic power stations. With many advantages such as high load performance, stability, anti-settling and resistance performance, it is very popular in photovoltaic industry.

The product is designed under a strict mechanical analysis, and different shapes, lengths and blade widths are selected according to different soil types, to ensure the stability and resistance of the whole ground screw mounting structure implant in the soil layer.
When the installation site is too hard or too much gravel, and it is difficult to insert a pillar directly into the ground, the ground screw mounting structure can be used to screw the pile into the ground with professional equipment, and the mounting structure is fixed on the screw pile.

2. Is it safe and reliable to use ground screw in solar power projects ?

The basis of the photovoltaic array support is an important part of ensuring the safe and normal operation of the solar power projects. In addition to having a certain strength and rigidity to meet the requirements of bearing capacity and deformation, it also needs to have certain corrosion resistance. It can be explained from three aspects: bearing capacity of single pile of ground screw mounting structure, connection test of foundation and upper bracket and anti-corrosion of screw pile, to demonstrated that whether the application of screw piles in solar power generation projects is safe and reliable or not.

① Bearing capacity of single pile of ground screw structure

After many measurements, the design pile length in the range of 1.5m~2.5m, which can obtain the maximum comprehensive benefit, is carried out according to different geological conditions and the pile type is designed to carry out static load test in the above places to obtain the ground screw pile. The bearing capacity of the single pile exceeds the standard, ensuring that the safety reserve of the ground screw pile foundation bearing capacity meets the requirements of current design specifications.

② Reliability of the connection between base and upper bracket

The ground screw pile can be easily connected to the upper brackets by fastening bolts, perforation bolts, flanges, etc., and can adjust the height of the column. Loads acting on photovoltaic mounting structure are self-weight, wind load, snow load, temperature load, seismic load, etc.,in which wind load is dominant. In the design life of photovoltaic power stations, wind loads have the characteristics of high frequency of action and variable direction of action. Therefore, no matter which way is used to connect with the mounting structure, the joint must not only have sufficient tensile and compressive strength, but also enhance anti-shake measures.

② Anti-corrosion measures for ground screw pile

China's Norms are stricter than British and European Norms. At present, the widely used specification for central shaft steel pipe of ground screw pile is 76 mm outer diameter with a wall thickness of 4 mm. Even in accordance with the provisions of JGJ94, the maximum corrosion of one side of the steel pile buried in the soil in the design life of 25 years, the amount is 1.25mm. Removing of the corrosion amount, the ground screw pile can still withstand the tensile and compressive load of about 130kN, which is much larger than the tensile or compressive load (about 20kN) of the photovoltaic support column.

In summary, the technology of ground screw mounting structure in solar power projects is safe and reliable.