At present, photovoltaic power generation systems built on buildings are widely used distributed photovoltaic power generation systems. 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 a building and is perfectly integrated with the building. It is also called a “construction type†and “building material type†photovoltaic building, and is a function of the photovoltaic array as a building structure. The part includes the replacement of traditional roofing materials with photovoltaic modules, such as: roof panels, tiles, slate tiles, metal roofs, windows, canopies, etc. As a part of the external structure of the building, it not only has the function of generating electricity, but also has the functions of building components and building materials. It even enhances the beauty of the building and forms a perfect unity with the building. Solar photovoltaic power generation systems attached to buildings are also referred to as "mounted" photovoltaic buildings. Its main function is to generate electricity that does not conflict with the function of the building and does not destroy or weaken the function of the original building. 1 common installation method The installation of photovoltaic modules varies depending on the type of roofing. Most of them are of separate design and have greater flexibility. The point-connected components are overhead and above the roof structure. They do not affect the performance of the existing roof and create better ventilation conditions, so that the solar panels can get the best Work efficiency, maintenance is also more convenient, especially for flat roof and slope roof. Flat roof BAPV common installation methods are: concrete weight method (including: cast concrete foundation method and precast concrete block weight method), in-situ concrete connection roof method, chemical anchor bolts and other methods. Slope roof common installation methods are: connection roof main structure method, special fixture fixing method, two-component adhesive bonding method (light installation method). 2 roof leakage analysis In the construction case, under the premise of correct design of structural load, if the construction is correct, safe, and civilized, then the construction method of roof drilling is not performed. Generally speaking, the waterproof layer of the roof will not be destroyed and the roof leakage will be caused. Such construction methods include concrete weighting method, steel connection method, special fixture fixing method, two-component adhesive bonding method, and the like. The following conditions may cause leakage on the roof: 1) When photovoltaic brackets are installed on the concrete flat roof or on the concrete sloping roof of the villa, the photovoltaic brackets shall be installed by means of pre-embedded bolts, expansion bolts or chemical anchor bolts; 2) In the case of photovoltaic brackets installed on the steel structure slope roof, for the case where the cross-section of the color steel plate ribs is trapezoidal, the bracket and the steel tile roof are securely fixed using self-tapping screws; 3) The cable jacket or roof water supply pipe through the roof; 4) The colored steel plate on the roof is rusted and leaks occur, or local areas are rusted; 5) Wrong, rough construction method. In any of the above situations, it is possible to destroy the original waterproof layer or waterproof tiles during the installation of the system, so that the roof may leak during the service life of the photovoltaic system. However, when the strip base is used and it is arranged perpendicular to the drainage direction, it may obstruct the drainage of roof rainwater and cause leakage. In addition, even though the roofing waterproofing treatment was performed during the installation of the photovoltaic system, due to the construction quality and the natural environment, such as in bad weather areas, experienced freeze-thaw cycles, and sun exposure, the roof cracked and accelerated the aging of the waterproof layer. And after damage, the roof is also likely to leak in the later period. 3 roof waterproof protection At present, the relevant national plans explicitly propose to encourage distributed photovoltaic power generation systems that combine construction and construction in the eastern and central regions. Under the strong support of national and local government policies, distributed photovoltaic power generation systems have become more widely used, accounting for more than 57% of the total installed capacity of photovoltaic power generation systems, making them an important future development direction. Photovoltaic modules installed on the roof should not only consider the sunshine and shadows, but also vary depending on the form of the roof. In engineering, the installation of components must take into account load, wind pressure resistance, earthquake resistance, drainage, waterproofing, and lightning protection. Because the project mainly involves the combination of photovoltaic supports and roofs, and thus relates to roof waterproofing problems, the design scheme and the construction quality of the project are not only related to the service life of the buildings, but also directly affect the normal operation of production activities and people’s lives. . At present, due to the introduction of distributed photovoltaic power generation in the market, competition is fierce, and the quality of design and construction is uneven. Attention should be paid to the waterproofing problem of the roof. Various types of roofing projects, including roofing screeds, gas barriers, waterproofing layers, thermal insulation layers, protective layers and the use of surface coverings above the roof structure, are an important division of housing construction. According to the performance of the building, the degree of importance, the function of use, and the reasonable service life of the waterproof layer. Larger public buildings and villa roofs in the city belong to Class II fortification; general industrial and civil buildings, ordinary houses, general office buildings, schools, hotels, etc. belong to Class III fortification. 4 roof waterproof The general principle of the roofing waterproofing treatment is: The guide should not be blocked, that is, to ensure that the node can smoothly let the water gulp out in the storm water and protect the roof from leaking. Therefore, in the design, the support base should first be arranged perpendicular to the drainage direction, and it should not obstruct the roof rainwater discharge. In addition, when the photovoltaic system is installed on the existing roof in the way of directly placing the support base on the roof, the base does not have a relationship with the structural layer of the original roof. Therefore, in order to ensure the safety of the structure, it must be ensured that the base is placed smoothly and neatly. , And need to take measures to fix, to avoid the phenomenon of overturning, slipping and so on. Since the base and the structural layer are not related, it is difficult to install an additional waterproof layer, and the waterproof layer of the original roof should be preserved as much as possible to prevent leakage. For the situation where holes must be broken to destroy the original roof, it is necessary to do it according to local conditions and do different treatments according to different situations. 1Concrete flat roof or villa concrete slope roof waterproof For new constructions of concrete flat roofs or villas with concrete sloping roofs (overlapped tiles), bolts should usually be embedded at the time of design and waterproofing of the roof should be done in accordance with conventional practices. For existing structures of concrete flat roofs or villa concrete slope roofs (overlapped tiles), the roof structure should be confirmed first. When the photovoltaic module base is connected with the structural layer, the surrounding of the metal embedded part at the top of the base is a weak link of water. If improperly handled, rainwater can easily seep from the bolt around the embedded part to reach the structural layer and cause corrosion to the stressed steel bars of the structural layer. , the formation of security risks. Therefore, when installing the PV module base, the waterproof layer should be laid on the upper part of the base and the metal embedded part, and sealed around the anchor bolts. The waterproof layer should be filled with a waterproof sealant to isolate the rainwater. An additional waterproof layer should be added to the lower part of the pedestal to prevent water from reaching the structural layer even if the top of the pedestal leaks. 2 waterproof metal roof For metal roofs, the steel structure of the photovoltaic system needs to penetrate the original waterproof layer and profiled steel plate, and be fixed on the main steel structure of the building; refer to the metal roof waterproofing method, and conduct steam insulation, thermal insulation and waterproof treatment. The focus of the construction is to rust, seal, and apply waterproof coatings to the base and exterior. Partial leakage points of metal roofs should be sealed with high quality neutral weatherproof sealants; for color steel sheets with severe local corrosion, they need to be replaced before installing PV modules. 1) For the case where the cross-section of the ribs of the color steel plate is trapezoidal: The photovoltaic support is usually connected with the color steel plate from the side or the top face through self-tapping screws. Self-tapping bolts must be provided with a weather-resistant sealing and waterproof gasket. After the self-tapping screws are fixed, the screws must be coated with a high-quality neutral weatherproofing sealant. 2) For cases with cable bushings that penetrate the roof: There are practices on the atlas of the existing national standard. In design and construction, it can be selected according to the actual situation of the actual project. 3) For the case of cables running through the roof: Tecchi covers can be used for waterproofing. Detegae is a waterproof structure for roofing. It is often used in roofing with color-pressed steel plates. It has good physical properties and chemical resistance and can overcome the problems of leakage of rigid waterproof materials. 3 waterproof treatment of roof hole For existing structures of concrete flat roof or villa concrete slope roof, if chemical anchor bolts are used to fix the bracket, the thickness of the protective layer or surface layer should be confirmed first. For a prefabricated floor slab with a large bearing capacity per unit area, a concrete layer of a certain thickness may be cast on the roof, and after curing, the bracket may be fixed using a chemical anchor bolt. For the slope roof of overlying tiles, the depth of drilling should be confirmed. After the chemical anchor bolts are fixed, the position where the bolts pass through the tiles should be treated with a waterproof sealant. Chemical anchor bolts have large bearing capacity, anti-fatigue and anti-aging properties. Some models can withstand dynamic loads and shock loads. They have no expansion force and no extrusion stress on the substrate. Therefore, they will not cause adverse effects on roof waterproofing. Conclusion During the construction of a distributed photovoltaic power generation system, there may be a risk of leakage of roofing rainwater, and attention should be paid to it. From the project site investigation stage to the deepening design stage, it is necessary to fully estimate and demonstrate the possible leakage risk of the roof in the future, and to conduct detailed investigation on any point where rainwater leakage may occur, and to adopt simple and effective technical means as far as possible. Waterproof technology treatment; In the construction phase, to avoid the secondary risk of water supply to the roof. 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