Several basic types of squares

There are several types of PV square array foundations, such as concrete pre-embedded foundations, concrete counterweight block foundations, helical ground pile foundations, direct buried foundations, concrete precast pile foundations, and ground-anchored foundations. Several types of foundations, such as buried foundation, precast concrete pile foundation, and ground-anchored foundation, are shown in Figure 6-1. These kinds of foundations have the advantages of firmness and reliability, and can be selected and applied according to the design and installation requirements of the power station and the geological soil condition of the construction site and the type of house roof structure.


1. Concrete pre-embedded foundation

Concrete pre-embedded foundation is a kind of foundation form with wider scope of application, and it is also the earliest traditional foundation form adopted by PV array, which is an independent foundation set under the fixed columns before and after the PV bracket, and the pre-embedded steel plate or pre-embedded bolts are poured in it through the on-site casting with concrete. The cross-section of this foundation can be made into a square, round, etc.. Sometimes, in order to solve the problem of low bearing capacity of the topsoil of the power station site, it is also possible to make the front and rear column foundations into one long foundation.

The advantages of the concrete embedded foundation is a wide range of applications, reliable force, without the need for special machinery construction, etc., the disadvantage is that the earth excavation and backfill project is large, the construction cycle is long, damage to the surrounding environment, the future will leave a lot of land in the land of waste and construction debris.

2.Concrete counterweight block foundation

Concrete counterweight block foundation is often used together with pre-embedded foundation for roof photovoltaic power generation system construction or remodeling, which can effectively avoid or reduce the damage to the roof waterproof layer and other structures.

3. Spiral ground pile foundation

Spiral ground pile foundation is an increasingly widely used form of foundation for photovoltaic racks in recent years, spiral ground pile is made of hot-dip galvanized steel pipe with helical blades, which can be large or small, continuous or intermittent, and continuous welding is adopted between the helical blades and the steel pipe. Common spiral ground piles are shown in Figure 6-3, with lengths of 0.55m, 0.7m, 1.0m, 1.2m, 1.6m, 1.8m, 2.0m, 2.7m and other specifications, and diameters of 60mm, 65mm, 76mm, 89mm, 114mm, 168mm, 219mm and other specifications, and tops of tubular, flanged, U-shaped fork, square cylinder, Cylindrical and other shapes, which can be chosen according to the need. The upper part of the foundation of screw ground pile is exposed to the ground, and the height of the support can be adjusted according to the terrain, and it is connected with the support column by bolts. The construction tools of Helical Ground Pile include electric pile driver and construction machines include Helical Ground Pile Drilling Rig.


Helical Ground Pile is a new type of foundation construction method. This method does not need to excavate the land and prefabricated grouting concrete, but only need to use special tools or special machinery to ram or drill directly into the ground. Compared with the traditional concrete foundation, it has the features of simple and convenient installation, saving time, labor and materials, making the foundation installation time shorter and the construction cost lower, and it can be moved and recycled anytime, anywhere, and it can maximize the protection of the site vegetation, and it is non-polluting to the land and the environment. When the system is dismantled at the end of its life, the foundation can be dismantled quickly, and there is no abandoned material in the land, and the site can be easily restored to its original appearance.

4. Directly buried foundation

Directly buried foundation is also known as the foundation of filled piles, directly buried foundation construction is the easiest, through the site trenching and pouring construction, only need to use the hole opener to open the hole and fill the concrete at the site, in the concrete is not solidified before the channel steel or steel pipe prefabricated parts can be directly inserted into the hole. While tamping the concrete, adjust the height of the foundation precast plane as needed. Although the construction process of the direct-embedded foundation is simple, the construction speed is slow and the construction period is long compared with that of the helical ground pile. The cost of the directly buried foundation is lower because it does not require high concrete strength grade. Directly buried foundation piles have no extrusion effect on the surrounding soil, and the self-supporting nature of the soil at the site requires higher requirements, so whether or not to use directly buried foundation needs to carry out preliminary geological survey tests, loose sandy soil layer and hard gravel, pebble soil layer are not suitable for directly buried foundation construction. Loose sandy soil layer is easy to cause collapse of holes, and hard gravel and pebble soil layer will cause difficulties in opening holes.

5. Concrete precast pile foundation

Concrete precast pile foundation is generally made by professional manufacturers, and its cross-section size is generally 200mm×200mm square or φ300mm round, with steel plates or bolts reserved at the top for convenient connection with the supporting columns, and the bottom is generally made into a pointed shape to facilitate the construction of the pile to be driven into or pressed into the soil layer. Precast concrete piles have the advantages of regular pile body, good quality of pile body, strong corrosion resistance, simple and fast construction, and the cost is a little higher than the direct buried foundation. Compared with helical ground piles, precast concrete pile foundation is easy to obtain larger structural resistance under the same geological conditions due to the relatively larger bottom area and side area, and the cost is also slightly lower than that of helical pile foundation. Only in the process of construction, the elevation of pile top is not easy to control, and the requirement of construction technology is higher.

6.Ground anchor foundation

The working principle of ground-anchored foundation is similar to that of helical pile foundation, which is more widely used in foreign countries. Its structure is installed in the lower part of the anchor with 2-3 upwardly retractable blades, when the anchor is pressed or screwed into the soil layer, the blades will be upwardly retracted, and after the anchor is in place, gently lifting the anchor upward or rotating it in the opposite direction, the retracted blades will be horizontally opened, so that the anchor will be firmly implanted in the soil layer. According to foreign construction experience, ground anchor foundation is the strongest and safest. However, the connection part of ground anchor and bracket needs to be specially customized, and the cost is very high.