1.Introduction
In today’s society, the quality of economic development has been significantly improved, which puts forward higher requirements for the application value of photovoltaic power generation technology, so that the promotion process of its integration with buildings is faced with more uncertainties. Under the current situation, it is necessary to examine the actual application status of photovoltaic power generation technology in a macroscopic way, accurately grasp the core essentials of its technical methods, take comprehensive policies, and comprehensively improve the integrated development effect of building integration. This paper discusses this issue.
Overview of photovoltaic power generation and building integration technology
For a long time, the relevant departments of the state have attached great importance to the integrated development of photovoltaic power generation and building integration technology, formulated and implemented a series of major policies, providing the basic direction for promoting the deep integration of photovoltaic buildings, made remarkable achievements and accumulated a wealth of valuable practical experience. At the same time, photovoltaic research and development institutions have also carried out a lot of research and exploration in the optimization of its integrated development with buildings, and achieved remarkable results. To a great extent, the combination of buildings and photovoltaic power generation system and buildings and photovoltaic devices has been realized. In spite of this, due to the influence of various factors, the current photovoltaic power generation and building integration technology still has many shortcomings and deficiencies. The structural form of technology application is relatively single, and the economic conversion efficiency is low, which is not conducive to the realization of long-term sustainable development, and must be attached great importance to. Under the above background, it is of profound practical significance to explore the practical application of photovoltaic power generation and building integration technology.
2.Discussion on the organizational form of the integration of photovoltaic power generation and architectural design
2.1 Photovoltaic devices as roofing materials
The rapid development of modern science and technology provides more abundant technical means for the application of integrated technology of photovoltaic power generation and architectural design, which makes the task of photovoltaic power generation difficult to complete in the traditional mode more feasible. The photovoltaic devices as building roof materials is one of the important paths. Roofing material is the key carrier of building engineering. Photovoltaic devices with excellent performance as roofing materials can effectively absorb solar radiation, and according to the different structural styles and space structures, the excess solar radiation can be stored and the electric energy can be converted successively. In this process, photovoltaic devices should be physically connected to the building roof through specific construction technology methods to prevent the impact of bad weather such as storms. At the same time, solar cell modules can be used to replace the building roof thermal insulation layer, which can not only ensure the building roof thermal insulation effect, but also effectively control the roof construction cost, and improve the photovoltaic power generation efficiency.
2.2 Application of photothermal power generation technology
The application of photovoltaic power generation technology and building integration gets rid of the shackles and limitations of the traditional rigid and solidified power generation mode, without using the silicon photoelectric conversion process with high cost, which greatly reduces the economic cost of the power generation process. Through the effective application of photothermal power generation technology, water heated by solar energy can also be stored. Even if there is no stable light in a certain period of time, it can also support the continuous power generation function of steam turbine to a certain extent and maintain the continuity of power generation. Photothermal power generation technology realizes the full and efficient utilization of solar illumination resources, fully taps the infinite value of limited resources, and can realize complementary power generation. Under the role of transfer and connection of joint thermal power station, the power generation task can be completed. With the deepening adjustment of the national energy structure, photovoltaic power generation technology based on the concept of photothermal will play a more important role in the field of building engineering and undertake more solar photovoltaic power generation tasks.
2.3 Application of photovoltaic curtain wall technology
The rapid development of economy and society has greatly improved people’s aesthetic taste, and more attention has been paid to the external appearance characteristics of architectural projects in urban construction and development, so that curtain wall decoration method occupies an increasingly important position in the field of architectural engineering. The practical application of the integration of photovoltaic power generation technology and building can also take the building curtain wall as the power generation carrier, and insert double glass photovoltaic modules into the glass curtain wall instead of ordinary materials, so that the building curtain wall not only has the traditional sound insulation, noise reduction and heat insulation effects, but also has the photovoltaic power generation function, maximize the use of solar light resources, and achieve the positive effect of green control. In addition, photovoltaic curtain wall technology can also effectively connect photovoltaic devices with exterior wall Windows, sunshades and other building components to achieve integrated design and operation and create specific landscape visual effects according to changes in actual needs.
3.Analysis of the practical application of the integration of photovoltaic power generation technology and building
3.1 Project Overview
Yellow River Hydropower photovoltaic Industry Technology Center building photovoltaic curtain wall installation project, located in Xining City, Qinghai Province. The curtain wall of this project takes the form of point-type stainless steel splint photovoltaic glass curtain wall system. The building is equipped with photovoltaic curtain wall and roof distributed power station, with a total installed capacity of 381.89kWp, among which the roof layout is 126kWp. The facade arrangement totals 246.14kWp, with its Middle East facade 94.3kWp, south facade 61.41kWp, west facade 58.47kWp and north facade 31.27kWp. This project has become a demonstration building of intelligent, scientific and energy-saving new energy in Qinghai Province.
3.2 Scheme Design
The physical performance grade of curtain wall is selected according to the geographical, climatic conditions, building height, body type, environment and the importance of the building in the area where the building is located, and combined with the specific regulations in the architectural design. Its classification conforms to the provisions of the current national code “Building Curtain Wall” GB/T21086. According to the calculation of the wind load standard value of the corner of the project is 1.0kN/m2. According to Article 5.1.1.4 of GB/T21086 “Building Curtain Wall”, the wind pressure performance classification standard of building curtain wall is set. For the deformation performance of the building curtain wall in plane, it should be designed according to the limit of the displacement Angle between the elastic layers of the main structure when the design is not seismic. The seismic design should be 3 times of the limit of elastic interlayer displacement Angle of the main structure.
3.3 Power generation efficiency analysis
According to the power generation in the first two years after the completion of the project, the average annual power generation of the project is about 357,300 KWH, among which the average annual power generation of the photovoltaic curtain wall is 179,900 KWH (75,700 KWH in the east, 5400 KWH in the south, 35,100 KWH in the west and 14,200 KWH in the north), the conventional single crystal of the roof is 161,300 KWH and the PERC single crystal is 17,000 KWH. The power generation data of one inverter on the roof, east, south, west and north surfaces from December 2019 to April 2020 are taken respectively to analyze and compare the power generation efficiency of each surface (see Table 1). According to the power generation data in Table 1 for 5 months, based on the power generation efficiency of the roof, the single watt power generation efficiency of the east, south, west and north sides is 81.17%, 94.04%, 24.54% and 15.94% of the roof, respectively. According to the calculation results, there is still a large gap between the efficiency of facade photovoltaic power generation and that of roof photovoltaic power generation. However, limited by the current technical level, the investment cost of facade photovoltaic power generation is much higher than that of roof photovoltaic power generation, which is an important reason hindering the large-scale development of photovoltaic building integration.
4.Closing Remarks
To sum up, under the influence of technical methods, building modes, effect evaluation, economic benefits and other factors, there are still many weak links and deficiencies in the integration process of photovoltaic power generation technology and building, which hinder the demonstration of the application advantages and value of photovoltaic power generation technology. Therefore, technical personnel should proceed from the objective and actual needs of construction engineering, fully follow the basic application principles and laws of photovoltaic power generation technology, innovate the application methods of technology, optimize the process control of technology application, lay the foundation for in-depth exploration of the value of photovoltaic power generation technology, and protect the sustainable, healthy and stable development of modern construction engineering.
