Photovoltaic support is an important part of photovoltaic power station, carrying the main body of photovoltaic power generation. Therefore, the choice of bracket directly affects the operation safety, damage rate and construction investment income of photovoltaic modules.
When choosing a photovoltaic bracket, it is necessary to select brackets of different materials according to different application conditions. According to the different materials used for the main stress members of photovoltaic supports, they can be divided into aluminum alloy supports, steel supports and non-metallic supports (flexible supports). Among them, non-metallic supports (flexible supports) are used less, while aluminum alloy supports and steel brackets have their own characteristics.
Non-metallic brackets (flexible brackets) use steel cable prestressed structures to solve the span and height problems of sewage treatment plants, mountains with complex terrain, roofs with low load-bearing, forest-light complementation, water-light complementarity, driving schools, and expressway service areas. It can effectively solve the technical difficulties that the traditional support structure cannot be installed, and effectively solve the construction difficulties of existing photovoltaic power stations in valleys and hills, with serious sunlight blocking and low power generation (about 10%-35% lower than photovoltaic power stations in flat areas). ) The power station supports have the disadvantages of poor quality and complex structure.
In general, non-metallic stents (flexible stents) have wide adaptability, flexibility of use, effective safety and economy of perfect secondary utilization of land, which is a revolutionary creation of photovoltaic stents.
A reasonable form of photovoltaic support can improve the system's ability to resist wind and snow. Reasonable use of the bearing characteristics of the photovoltaic support system can further optimize its size parameters, save materials, and further reduce the cost of photovoltaic systems.
The loads acting on the foundation of the photovoltaic module bracket mainly include: the self-weight (constant load) of the bracket and the photovoltaic module, wind load, snow load, temperature load and earthquake load. Among them, the main control effect is wind load, so the foundation design should ensure the stability of the foundation under the action of wind load. Under the action of wind load, the foundation may be pulled up, fractured and other damage phenomena, and the foundation design should be able to ensure that the acting force No damage occurs.
So, what are the types of ground photovoltaic support foundations and flat roof photovoltaic support foundations? What are their characteristics?
Ground photovoltaic support foundation
Bored pile foundation: It is more convenient to form holes, the top elevation of the foundation can be adjusted according to the terrain, the top elevation is easy to control, the amount of concrete reinforcement is small, the amount of excavation is small, the construction is fast, and the damage to the original vegetation is small. However, there are concrete holes and pouring on site, which are suitable for general fill, clay, silt, sand, etc.
Steel spiral foundation: It is easy to form holes, and the top elevation can be adjusted according to the terrain. It is not affected by groundwater. It can be constructed as usual in winter climate conditions. The construction is fast, the elevation adjustment is flexible, and the damage to the natural environment is small. The damage to the original vegetation is small, and no field leveling is required. Suitable for deserts, grasslands, tidal flats, next door, frozen soil, etc. However, the steel used is larger, and it is not suitable for strong corrosive foundations and rock foundations.
Independent foundation: the strongest resistance to water load, flood resistance and wind resistance. The amount of reinforced concrete required is the largest, the labor is large, the amount of earthwork excavation and backfill is large, the construction period is long, and the damage to the environment is large. It has been rarely used in photovoltaic projects.
Reinforced concrete strip foundation: This type of foundation is mostly used in flat uniaxial tracking photovoltaic supports with poor foundation bearing capacity, in areas with relatively flat sites and low groundwater levels, and with high requirements for uneven settlement.
Prefabricated pile foundation: prestressed concrete pipe piles with a diameter of about 300mm or square piles with a cross-sectional size of about 200*200 are driven into the soil, and steel plates or bolts are reserved on the top to connect the front and rear columns of the upper bracket, and the depth is generally less than 3 meters. Simpler and faster.
Bored pile foundation: low cost, but higher requirements for soil layer, suitable for silty soil with a certain density or plastic, hard plastic silty clay, not suitable for loose sandy soil layer, soil quality Harder pebbles or crushed stones may have problems with porosity.
Steel screw pile foundation: It is screwed into the soil by special machinery, the construction speed is fast, no site leveling is required, no earthwork or concrete is required, and the vegetation in the field is protected to the greatest extent. The height of the bracket can be adjusted according to the terrain, and the screw pile can be reused.
Flat roof photovoltaic support foundation
Cement counterweight method: pouring cement piers on the cement roof, this is a common installation method, the advantage is stable and does not damage the roof waterproofing.
Prefabricated cement counterweight: Compared with the production of cement piers, it saves time and saves cement embedded parts.