At present, the photovoltaic power generation system built on a building is a widely used distributed photovoltaic power generation system. The buildings involved include civil buildings, public buildings, industrial buildings and other buildings that can carry photovoltaic power generation systems. It is a photovoltaic power generation system that is designed, constructed and installed at the same time as the building, and forms a perfect combination with the building. Some include replacing traditional roofing materials with photovoltaic modules, such as: roof slabs, tiles, slate tiles, metal roofs, windows, shelters, etc. As a part of the building's external structure, it not only has the function of generating electricity, but also has the function of building components and building materials. It can even enhance the beauty of the building and form a perfect unity with the building.
Solar photovoltaic power generation systems attached to buildings are also known as "installed" photovoltaic buildings. Its main function is power generation, which does not conflict with the function of the building, and does not damage or weaken the function of the original building.
Common installation methods
The installation of photovoltaic modules varies depending on the type of roof. Most of them adopt a separate design with greater flexibility. They are suspended above the roof structure with point-type connection members. While not affecting the original roof performance, it creates better ventilation conditions and enables the solar panels to obtain the best. Work efficiency and maintenance are more convenient, especially suitable for flat roof and slope roof.
Common installation methods for flat roof BAPV include: concrete counterweight method (including: cast concrete foundation method and precast concrete block counterweight method), cast-in-place concrete connection roof method, chemical anchor bolting method, etc.
Common installation methods for sloping roofs are: connecting the roof main structure method, special fixture fixing method, and two-component adhesive bonding method (light installation method).
Analysis of the causes of roof leakage
In the construction case, under the premise of correct design of the structural load, if the construction is correct, safe, and civilized, then the construction method without roof drilling will generally not damage the roof waterproof layer and cause roof leakage. Such construction methods include: concrete counterweight method, steel structure connection method, special fixture fixing method, two-component glue bonding method, and the like.
There are some situations that may cause leakage on the roof:
1) When installing photovoltaic brackets on concrete flat roofs or concrete slope roofs of villas, the project of installing photovoltaic brackets by using embedded bolts, expansion bolts or chemical anchor bolt fixing methods;
2) When installing a photovoltaic support on a steel structure sloping roof, for the case where the cross section of the color steel plate rib is a trapezoidal section, the self-tapping screw is used to firmly fix the support to the color steel tile roof;
3) Cable bushings or roof water supply pipes pass through roof panels;
4) The roof color steel plate is corroded and leaks, or the local area is corroded;
5) Wrong and rough construction methods.
The above several situations may damage the original waterproof layer or waterproof tile during the system installation process, and cause the roof to leak during the service life of the photovoltaic system. However, when a strip-shaped base is used and is arranged perpendicular to the drainage direction, it may hinder the drainage of roof rain and cause leakage. In addition, even if the roof is waterproofed during the installation of the photovoltaic system, due to the construction quality and natural environment, such as in the harsh climate area, the roof has cracked due to the annual freeze-thaw cycle, sun, etc., and the waterproof layer is aged After the damage, the roof is likely to leak at a later stage.
Roof waterproof fortification
At present, relevant national plans explicitly propose to encourage the construction of distributed photovoltaic power generation systems in the central and eastern regions. With the strong support of national and local government policies, distributed photovoltaic power generation systems have become more and more widely used, accounting for more than 57% of the total installed capacity of photovoltaic power generation systems, which will become an important development direction in the future.
The installation method of photovoltaic modules on the roof should not only consider sunlight and shadow, but also vary according to the form of the roof. In engineering, the installation of components must consider issues such as load, wind pressure resistance, earthquake resistance, drainage, waterproofing, and lightning protection. Because the project mainly involves the combination of photovoltaic brackets and roofs, and then the roof waterproofing problem, the quality of the design scheme and construction quality not only affects the service life of the building, but also directly affects production activities and the normal progress of people's lives . At present, as distributed photovoltaic power generation is in the market introduction period, competition is fierce, and the quality of design and construction is uneven, and more attention should be paid to the waterproofing of the roof.
Various types of roofing projects, including roofing screeds, air barriers, waterproofing layers, thermal insulation layers, protective layers and use surface layers above the structural layer of the roof, are an important part of building construction. According to the building's performance, importance, use function and reasonable service life of the waterproof layer.
Larger public buildings and villa roofs in cities belong to Class II fortifications; general industrial and civil buildings, ordinary houses, general office buildings, schools, hotels, etc. belong to Class III fortifications.