Solar energy; Photovoltaic glass curtain wall; Green building; Photovoltaic power generation
With the increase of population and the development of economy, the traditional petrochemical energy is gradually decreasing, which causes environmental pollution and ecological deterioration, and people begin to look for new energy sources. Compared with wind power, hydropower and nuclear power, solar energy is continuous, extensive and clean, making it the best choice for green building energy. Solar photovoltaic technology has the advantages of no consumption of fossil fuels, safe use and no pollution, and has become the main development direction of solar energy utilization. Among them, photovoltaic glass curtain wall technology integrates solar photovoltaic products into buildings, forming photovoltaic building integration, which is widely used in green buildings.
1 principle of photovoltaic glass curtain wall
Photovoltaic glass curtain wall is to use special resin to stick solar photovoltaic cells between two pieces of glass, and convert solar energy into electric energy through the cells. Generally speaking, photovoltaic glass curtain wall is a kind of glass curtain wall that can generate electricity, which mainly includes photovoltaic cell modules, batteries, controllers, inverters and other important parts.
1. 1 photovoltaic cell principle
Photovoltaic cells can directly convert light energy into electric energy through photoelectric effect, which is an important part of photovoltaic glass curtain wall. When the sun shines on the surface of the battery, the silicon material inside the battery absorbs a part of photon energy, and the electrons inside the silicon atom jump and gather on both sides of the pn junction to form a potential difference. When the external circuit is connected, current will be generated and photovoltaic power generation will be formed.
1.2 photovoltaic cell module
Photovoltaic cell is the key component of photovoltaic power generation system. There are mainly three kinds: monocrystalline silicon, polycrystalline silicon and amorphous silicon, among which amorphous silicon photovoltaic cells are becoming the development direction and mainstream of photovoltaic cells.
One is monocrystalline silicon photovoltaic cells, which use high-purity monocrystalline silicon rods as raw materials, cut into thin slices, processed into single pieces, and combined into photovoltaic panels as needed. A plurality of photovoltaic panels form a photovoltaic cell array, and the conversion efficiency is about 15%. It has the characteristics of mature technology, high conversion rate and large output.
The second type is polysilicon photovoltaic cells, which are cut by pouring silicon blocks. The conversion efficiency is about 12%, which has the characteristics of simple production process, low price and short service life.
Thirdly, amorphous silicon photovoltaic cells, that is, thin-film photovoltaic cells, are made by evaporating extremely thin silicon wafers onto a carrier. It has the characteristics of light weight, simple process, low energy consumption, weak light power generation and low conversion efficiency.
1.3 battery
Under the influence of different seasons, climate, solar irradiation angle and other factors, photovoltaic cells will produce uneven current. When the generated electric energy exceeds the usage, the battery can store excess electric energy and release electric energy when the generated electric energy cannot meet the usage, thus balancing the power supply of the system.
1.4 controller and inverter
The electric energy generated by photovoltaic cells is direct current, which needs to be converted into charging current and voltage to meet the requirements of the battery through the controller in order to achieve the purpose of storing electric energy. In addition, in the case of grid-connected operation, the controller will also control the storage battery to provide the required electric energy for the controller. The electric energy generated by photovoltaic cells is direct current. In order to realize grid-connected operation, it is necessary to use an inverter to convert direct current energy into alternating current.
2 photovoltaic glass curtain wall structure
The photovoltaic glass curtain wall consists of two pieces of toughened glass, inside and outside, with a composite layer composed of PVB film composite thin-film photovoltaic cells in the middle. The batteries are connected in series and parallel to the lead terminals through wires to draw out current, thus forming a photovoltaic glass curtain wall unit. A plurality of photovoltaic glass curtain wall units form a photovoltaic glass curtain wall, and the current of each photovoltaic glass curtain wall unit is summarized by a current collector to finally form a photovoltaic glass curtain wall power generation system. Ultra-white glass is used outside the curtain wall, and heat reflective coated glass is used inside the curtain wall. Photovoltaic solar cells are installed between inner and outer glass in the form of shutters.
3-angle photovoltaic glass curtain wall
The angle of photovoltaic glass curtain wall involves two aspects: one is the orientation of curtain wall. Through experiments and analysis, the position of the sun rising in winter is about 30 degrees southeast of due south and 30 degrees southwest at sunset. There is little difference in conversion efficiency of photovoltaic glass curtain wall in this range, and photovoltaic glass curtain wall can be set in this range; The second is the angle of photovoltaic solar cells. Through experiments and analysis, combined with the local latitude and the occlusion of upper and lower blades, the optimal inclination angle can be determined to be about 45 degrees.
4 Characteristics of photovoltaic glass curtain wall
4. 1 does not affect the architectural beauty.
Architecture is a solidified art, and the use of photovoltaic glass curtain wall should not affect the appearance of the building. Therefore, in the design and construction of photovoltaic glass curtain wall, junction boxes, bypass diodes, connecting wires, etc. Hidden in the curtain wall structure, it has the advantages of wind, rain and sun protection, prolonging the service life of the equipment and not affecting the appearance of the building. The surface of solar cells can be made into blue, green, yellow, black and other colors, which can well match the color of building curtain wall and ensure the green and beautiful building.
4.2 does not affect the building lighting.
Light is the soul of architectural art, and the photovoltaic glass curtain wall adopts smooth ultra-white tempered glass and heat reflection coated glass, with solar cells obliquely arranged in the middle. The lighting degree of curtain wall can be controlled by the arrangement gap of solar cells, which can fully meet the lighting needs of buildings.
4.3 Does not affect the safety of buildings
Photovoltaic glass curtain wall not only needs to meet the needs of photovoltaic power generation, but also needs to meet the wind pressure deformation performance, rainwater leakage performance, air permeability performance and building safety performance of curtain wall. In view of these demands, photovoltaic glass curtain walls with different mechanical properties are needed in different areas, different building heights and different installation methods. According to the national building code and curtain wall code, the thickness of tempered glass should be calculated scientifically. The PVB film in the middle of the module has good adhesion, toughness and elasticity, and has certain energy absorption and bonding effect. When the glass is broken, the fragments will adhere to the film and will not be scattered, which reduces the possibility of injury and further improves the safety performance of the curtain wall.
4.4 Easy installation
The design and installation technology of glass curtain wall is mature, which makes the installation of photovoltaic glass curtain wall equally convenient and fast. Component curtain wall is the most widely used structural form at present, with mature technology, strong adaptability of the main structure and flexible construction means; The unit curtain wall adopts industrial processing and molding, which has the advantages of guaranteed quality, low labor cost and short construction period, and can bring greater economic benefits; The double-layer ventilation curtain wall can provide ventilation, sound insulation and heat insulation, effectively solve the heat dissipation problem of the battery module, prolong the service life of the battery module and reduce the heat emitted by the module to the room.
4.5 Green environmental protection
Photovoltaic glass curtain wall has two functions of photovoltaic power generation and ordinary curtain wall, which does not need to occupy additional building area and saves the supporting structure of photovoltaic system. It not only has the energy-saving functions of flame retardant, heat insulation and noise reduction, but also has the green environmental protection characteristics of no consumption of petrochemical energy and water resources, no pollution, no greenhouse gas emission and less light pollution.
5 abstract
Solar energy is the most widely distributed renewable energy and has broad development prospects. The application of photovoltaic glass curtain wall technology in green building can make photovoltaic glass curtain wall and building combine perfectly and harmoniously, and can generate energy intelligently. At the same time, it has the functions of sound insulation, heat insulation, safety, decoration and harmonious environment, which has become the development trend of combining solar energy utilization with construction industry and has broad application value and development prospects.
refer to
[1] He Shaoyao, Chu, Li, et al. Research and application of solar photovoltaic glass curtain wall technology [J]. Journal of Architecture, 2009, (2): 102- 103.
[2] Yue Weiwei, Zhang Huijuan. Effective utilization of solar photovoltaic power generation in green buildings [J]. Building Energy Conservation, 20 12, (1):34-37.
Bai Bo, Zhou Chuanhui, Zou Fangbo, et al. Brief introduction of solar photovoltaic glass curtain wall technology and application [J]. Science and Technology Entrepreneurship Monthly, 201,24 (17):135-136.
Liang yueming. On the Integrated Application of Photovoltaic Power Generation and Building [J]. Urban Construction, 20 10, (33):223-224.
[5] Liang Rui, Zhang Qun and Liu Jiaping. Green Building Design Combined with Solar Energy Application Technology [J]. Shaanxi Architecture, 20 10, (6):4-7.
Xie Kong, Bai Mei, Deng Kang. Experience of integrated design of solar energy and buildings [J]. Industrial Architecture, 2008, (2):114-118.
Li, He Shaoyao, Zhang Jingnong. Study on the application of solar photovoltaic cells in building curtain wall [J]. huazhong architecture, 2009, (1):15-17.