This type of support was widely used in early photovoltaic (PV) projects (see Figure 1). It is equipped with front and rear legs of different lengths, each bolted to the foundation. One end of the diagonal brace is supported at the base of the longer column, and the other end at the middle of the inclined beam. Longitudinal purlins are supported on the inclined beam to form the PV panel support system. The structure is a geometrically invariant system with no redundant constraints.
The common connection between the column base of such supports and the foundation is shown in Figure 2. If the column base is designed as a hinged connection, the support will have large deformation and high steel consumption. Additionally, the breakage rate of frameless PV modules caused by support deformation is very high.
The triangular support has high requirements for the connection form between the legs and the foundation. To effectively solve this problem, the improved triangular support was developed through in-depth research. Based on the triangular support, it adds additional diagonal braces to enhance the overall stability. Although the steel consumption increases slightly, the front and rear columns of the support deform synergistically, reducing total deformation. It is suitable for various PV module supports, especially projects with high wind loads, uneven terrain or mountainous areas, where high requirements for support integrity and deformation control are required.
The herringbone support follows the "three-rigid-body rule" in structural mechanics: three rigid bodies connected pairwise by three single hinges not collinear form a geometrically invariant system with no redundant constraints. It is also a simple two-member support structure. By eliminating the need for legs of different lengths, it has lower steel consumption, a simpler structure, and easier construction and installation.
However, this type of support has certain limitations:
- It cannot be adjusted in height, so it is only suitable for flat terrain with small undulations.
- The elimination of unequal-length legs increases the cantilever length of the crossbeam. When the upper load increases, the support deflection will also increase, posing risks to the stability of the PV support system and the breakage rate of frameless PV modules. Therefore, herringbone supports are only used in engineering environments with low wind loads.
To effectively address the disadvantage of high steel consumption in the crossbeam of the herringbone support while incorporating the advantages of the triangular support, the improved herringbone support was developed. It adds a rear leg to the herringbone support, thereby reducing the cantilever length of the crossbeam, enhancing the stability of the support system, and lowering the breakage rate of PV modules. The steel consumption of the improved herringbone support is only slightly higher than that of the conventional herringbone support, but significantly lower than that of two triangular supports.
The single-column PV support structure mainly consists of key components such as main beams, secondary beams, front supports, rear supports, steel columns, hoops, and single-pile foundations. It uses two diagonal braces to support the main and secondary beams, which in turn hold the PV panels. The connection between the steel diagonal braces and the single-pile foundation is achieved through hoops, featuring simplicity and high efficiency.
Meanwhile, the single-column PV support structure occupies less space, allowing full utilization of the land between the front and rear rows of PV strings. The front and rear supports of the single-column structure are extended versions of those in the double-column PV support structure. Additionally, the single-column structure adds components such as hoops and steel columns, resulting in significantly higher steel consumption compared to the double-column PV support.
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