The design and selection of photovoltaic foundations and brackets are key factors in ensuring the long-term stable operation of solar photovoltaic power generation systems. When designing, fully consider the safety, durability, and economy of the structure, while also determining the most suitable solution based on specific installation environments and application scenarios.
Photovoltaic basic design
1. Vertical bearing capacity verification: All types of foundations must undergo vertical bearing capacity verification for compressive and tensile strength to ensure that the foundation can withstand pressure or tension from above.
2. Horizontal bearing capacity verification: For pile foundations, in addition to vertical bearing capacity, horizontal bearing capacity verification should also be carried out to ensure their stability under lateral force.
3. Overall stability verification: Especially for micro steel piles, it should be ensured that the overall stability of the entire system is not affected by external factors.
4. Basic dimensions and depth: The specific dimensions and burial depth of the foundation are determined based on the calculated overturning moment, pull-out resistance, and other parameters. For example, the initial set basic size is 400mm x 400mm, and the spacing depends on specific requirements.
Bracket design
1. Material selection: Common photovoltaic bracket materials include aluminum alloy (Al6005-T5 surface anodized), stainless steel (304), galvanized steel parts (Q235 hot-dip galvanized), etc. Each material has its own characteristics, such as aluminum alloy being lightweight and easy to install, but having relatively low load-bearing capacity; Although stainless steel has a high cost, it performs well in harsh environments; Galvanized steel parts have good cost-effectiveness, but they are relatively heavy.
2. Structural form: Choose fixed, adjustable inclination, or automatic tracking brackets according to different application scenarios. Fixed bracket is suitable for areas with little change in lighting angle; The tracking bracket adjusts its angle with the position of the sun throughout the day, thereby improving power generation efficiency.
3. Heat dissipation performance: Some new bracket designs enhance air circulation by optimizing component layout, which helps improve the heat dissipation effect of photovoltaic systems and thus enhance work efficiency.
Design Example
Residential roof application: For sloping roofs, design brackets parallel to the roof, usually about 10-15 cm away from the roof surface, to facilitate ventilation and heat dissipation. Considering the aging problem of residential buildings, the bracket design ensures that it can withstand additional loads.
Commercial buildings: In such projects, the design of photovoltaic brackets should not only meet the requirements of strength, stiffness, and stability, but also comply with seismic, wind, and corrosion resistance standards. In addition, consider factors such as local climate conditions and building design standards.
Agricultural photovoltaic power station: adopting an integrated design and separate installation method, the photovoltaic modules are installed on high brackets and maintained at a certain angle to maximize the reception of solar radiation. This method achieves on-board power generation without affecting the land use below, such as planting crops or breeding.
Parameter reference
Component size: Assuming the component size is 2094mm x 1038mm, with a thickness of approximately 35mm and a weight of approximately 20kg/㎡.
Wind load parameters: According to the GB50797-2012 standard, the wind load shape coefficient μ s=1.3, the wind pressure height variation coefficient μ z depends on the ground roughness category (A-D), and the basic wind pressure ω 0 is determined by the historical meteorological data of the project location.
Basic dimensions: For an independent foundation, one configuration is 0.4m long x 0.4m wide x 0.5m high; For strip foundations, it is 0.8m long x 0.4m wide x 0.4m high.
Several common evaluation methods and their characteristics for assessing the load-bearing capacity of buildings:
1. Design drawing analysis
Evaluators will make preliminary judgments based on the architectural design drawings. In design drawings, it is usually clearly marked which walls are load-bearing walls, which are generally thicker and located in key positions of the building, such as foundations, between floors, and below the roof. Design drawings are scientifically planned by structural engineers based on the overall structure and load distribution of the building, providing important information about the location and thickness of load-bearing walls.
2. On site investigation
In addition to relying on design drawings, on-site investigation is also an indispensable part. This includes verifying whether the actual materials and structure of the wall meet the design requirements through visual inspection and the use of professional tools and techniques such as ultrasonic testing and core sampling. This method provides a more intuitive understanding of the condition of the wall and can identify existing issues such as cracks or material aging.
3. Static detection
Static testing refers to the use of specialized equipment (such as pressure sensors, data acquisition devices, etc.) to measure the load-bearing performance of the ground or structure in a static state. This method is suitable for new buildings or when precise results are needed. Obtaining very accurate data through this method also means higher costs and technical requirements.
4. Dynamic detection
For structures that require evaluation of their performance under dynamic loads, such as bridges, roads, etc., dynamic detection methods are used. This means simulating factors such as vibration or impact in actual usage situations to test the response of the structure under these conditions. Although this method can provide information that is close to real-life scenarios, it also requires complex operational processes and support.
5. Computer simulation calculation analysis
Computer simulation is a modern technological means that allows us to create a virtual model for detailed mechanical analysis. The evaluation process involves collecting information on the design and construction data, appearance quality status, and usage of the building, followed by structural review and verification, and ultimately drawing conclusions and making recommendations. The advantage of this method lies in its fast speed, relatively low cost, and wide application, especially in the fields of industrial construction and factory buildings.
6. Actual measurement method
The actual measurement method refers to directly measuring the structure on site, including factors such as size and material, in order to evaluate its load-bearing capacity. The advantage of this method is that it can directly reflect the true condition of the structure, but it also requires professional measuring equipment and technical support, and may be affected by measurement errors.
7. Empirical rules
In the absence of detailed information, empirical rules can serve as a rapid estimation method. This method relies on past experience and patterns to evaluate the load-bearing capacity of the structure. Although simple and feasible, its accuracy is low and can only provide rough results.
8. Load bearing test
In order to obtain the most accurate limit value of floor load-bearing capacity, sometimes on-site load-bearing tests are conducted. This experiment involves loading sandbags or water in batches until the deformation value of the floor beams and slabs approaches the specified limit. Although this approach is the most direct and effective, it is also the most time-consuming and labor-intensive, usually only adopted in particularly important situations.
