With the gradual decline of centralized photovoltaic power generation, the distributed photovoltaic market has grown stronger. As the main force of distributed photovoltaic power generation, the family rooftop power station is favored by all parties and uses the roof of the idle plant for secondary use. In 2016, the “630†rush to set off a surge of photovoltaic power plants installed on the roof of their homes, and many residents are also eager to try. Zhang Yanjie, deputy director and chief engineer of the Distributed Development Center of Hebei Energy Engineering Design Co., Ltd., at the 5th household conference, introduced the knowledge of the site selection and design of the rooftop power plant to the PV colleagues present. First, the roof power station survey elements When many owners invest in rooftop PV power plants, they will be very concerned about the feasibility of rooftop photovoltaics, installed capacity, investment returns, and cooperation models. Distributed rooftop PV surveys are part of the project's preparatory work, and they collect information on rooftops through field surveys. Prepare for the subsequent design of the optimal plan and investment income analysis. The professional survey records are an important factor in evaluating the roof power station. The preliminary investigation of the rooftop power station mainly includes the following elements: (1) the construction period of the factory; (2) the condition of the roof; (3) the type of the roof board; (4) the corrosion condition of the colored steel plate; (5) the access distance of the power grid; (6) Original plant design data, electricity load, etc. Based on the summary information obtained, the following table is formed to evaluate the roof. According to the above table, the project can be scored, and the overall over-comprehensive rating is not a suitable site for the plant. First of all, we must look at the construction time of the plant, because the life of the photovoltaic power plant is about 25 years. If the construction time is too long and the follow-up period is less than 25 years, it will not meet the requirements. Look at the condition of the roof, the roof is relatively neat, investment is low, and the return is good. Among them, there are roof installation problems on the roof of the color steel plate, and the design of hole punching is more problematic. Then there is the problem of load-bearing of the plant. The bearing is whether the plant can be used as a prerequisite for the construction of the power station. Then there is the gap between the grids. The shorter the distance, the smaller the investment. It also depends on the scale of construction of the power station. The greater the scale, the lower the investment in transfer and conversion of the power station. Finally, the data is complete. 1 The design data includes the design information of the building's construction, structure, electrical drawings, etc.; 2. The original data of the plant, including land certificates, real estate and other data. The on-site survey of photovoltaic power plants generally adopts GPS positioning, taking site photos, and measuring the roof protrusions to obtain preliminary preliminary results. GPS positioning is generally used to obtain the actual plant location relationship from Google Earth. Photographs can truly reflect the current state of the plant, and measuring the roof protrusions can provide the basis for subsequent component drawings. Second, the proposal of site selection Although the photovoltaic industry has developed over the years, design specifications and acceptance criteria do not make reasonable recommendations for site selection, especially for rooftop power stations. Summarize past experience four points of experience. 1) Pay attention to the design and use of the original plant All production enterprises, including warehousing companies, have a hazard rating. According to the “Building Fire Protection Design Code†GB50016-2014, the fire hazard levels of production workshops and storage warehouses can be divided into A, B, C, D, and E, due to A and B. The workshops and warehouses have high fire hazard levels, so it is strictly forbidden to build photovoltaic power plants in the upper part of such plants. Class C plants and warehouses can be determined in accordance with the functions of the lower plant and combined with the production process. D and E plants can be used as power stations. location. 2) It is forbidden to build a photovoltaic power plant at the Linjian plant. According to the specification requirements of the design of the building years of use 1, temporary structure of 5 years; 2, easy replacement of structural components for 25 years; ordinary houses and structures for 50 years; 4, monumental and particularly important building structure for 100 years. The design life of the photovoltaic power station is 25 years. The temporary construction structure cannot meet the requirements for the durability of the power station design. Therefore, the construction of the photovoltaic power station cannot be implemented for the temporary buildings and structures. Especially in the factory area, some temporary passages, temporary carports and other buildings were built. The service life of the plant has been more than 10 years, and the rust of the roof color plate is serious or the leakage of the water-proof layer is serious. For such a plant, we must choose it carefully. 4) Select the structural capacity of the plant to meet the requirements for the construction capacity of the photovoltaic power station. According to the requirements of the "PV Power Plant Design Code," adding photovoltaic power generation systems to existing buildings requires the review of the building structure and electricity, and should meet the safety requirements of the building structure and the electrical facilities. According to the requirements of 10.1.4 of this specification, when a photovoltaic power generation system is added to an existing building, it should be in accordance with the requirements of the "Reliability Assessment Standards for Industrial Buildings" GB50144 and "Civil Building Reliability Appraisal Standards" GB50292 according to the types of buildings. Perform reliability assessment. Buildings with seismic intensity of 6~9 degrees should also be evaluated according to their fortification intensity, seismic fortification type, follow-up service life, and structure type, in accordance with the “Building Earthquake Appraisal Standard†GB50023. 5) It is appropriate to build the roof form of the power station. (1) Satisfy the requirements set forth in the preceding four articles. (2) Color steel plate in the form of angle-type or stand-up color steel plate (3) Waterproofing of concrete roofs is good. (4) less protruding roofs and coverings Third, the roof power station structural design points 1, reinforced concrete roof Reinforced concrete roofs are divided into upper and lower roofs. The upper roofs are mostly flat roofs, while the upper roofs are not common in flat roofs and slope roofs. The structural form of the flat roof is mostly reinforced concrete frame structure, and the slope of the drainage is mostly 2% of the slope of the material; the structure of the factory building of the slope roof is mostly reinforced concrete bent structure, and the common slope is 10%. The roof live load of the top man roof is mostly 2.0 kN/m2, and the live roof load of the man roof is mostly 0.5 kN/m2. According to different types of waterproof roof, the roof is divided into flexible waterproof roof (waterproof layer exposed) and rigid waterproof roof (waterproof layer in the interior, the outer surface of the 40-fine fine stone concrete). For different types of factory buildings and roofs with different waterproof forms, different design schemes are adopted for the bracket design. For reinforced concrete roofs, photovoltaic modules can be laid parallel to the slope of the roof, or they can be arranged in a certain angle of inclination. The connection methods of photovoltaic power station and reinforced concrete roof structure mainly include (1) concrete weight, (2) anchorage connection, and (3) structural adhesive connection. Concrete counterweight Reinforced concrete roofing connection Structural adhesive connection 2, color steel form roof. Photovoltaic power plants are connected to reinforced concrete roof structures mainly through (1) connection through photovoltaic special fixtures (2) riveted or cold-welded connections. The general design of the original color steel plate roof is mostly 0.3KN/m2, and the full load of the roof photovoltaic power station is 0.15KN/m2. Photovoltaic fixture connection II (small angle) Fourth, power station revenue analysis model If you want to invest in PV power plants, you need to consider bank loans, financing and other financial issues, but also calculate how much the power plant's yield is, and how much rent is appropriate. Therefore, in the early development stage of the project, it is adept at using economic evaluation tools to initially evaluate the economic benefits of the project. There are the following modes: Mode 1: Directly calculate project economic return indicators for investment decisions The investor provides boundary conditions, such as loan proportions and interest rates, operation and maintenance costs, depreciation rates, etc.; the design institute determines the single-wattage cost (static and dynamic) according to the design plan, and calculates the starting power; the design institute is based on the grid connection mode and operation mode. Calculate the price of electricity. According to the above conditions, directly calculate the project income indicators, such as the internal rate of return IRR, investment recovery period, for the investor to make decisions. Mode 2: Compare the economic benefits of investors and rooftop property owners in different grid-connected models (1) According to the design plan, the design institute determines the single-wattage construction cost (static and dynamic) and the amount of power generation; (2) The investor has boundary conditions such as loan ratio and interest rate, operation and maintenance cost, depreciation rate, etc.; (3) Design Institute Calculate various grid-connected modes and operating modes to calculate electricity prices. Based on the above conditions, the income of the investor and the roof equity party in different modes is measured and used for investment decisions. Mode 3: Back-calculate the EMC electricity price for the investor to negotiate the electricity price discount with the roof equity party The investor has determined the energy management mode of the contract and used the self-utilized electricity to access the Internet. The design institute calculated a user's discounted electricity price; the investor has an expected internal rate of return IRR for the entire investment or capital; the investor gives the boundary conditions, such as loans. Proportion and interest rate, operation and maintenance cost, depreciation rate, etc.; the design institute determines the single tile cost (static and dynamic) according to the design plan and calculates the starting power. Based on the above conditions, an electricity price is calculated in reverse and the user compares the electricity price to determine the EMC electricity price discount. Mode 4: Calculate the rent on the roof for the owner to negotiate with the roof equity (1) The investor has determined the full amount of access to the Internet, using a fixed roof rental settlement; (2) The investor has an expected internal rate of return IRR for the entire investment or capital; (3) The investor gives the boundary conditions, Such as loan ratio and interest rate, operation and maintenance cost (excluding rent), depreciation rate, etc.; (4) Design institute determines single-tile manufacturing cost (static and dynamic) and power generation according to the design plan. According to the above conditions, under the premise of the investor’s expected revenue, a roof rent is calculated in reverse. Mode 5: Back-calculate the financing rate, (1) The investor has determined the grid-connected mode and operating mode; (2) The investor has an expected internal rate of return IRR for the entire investment or capital; (3) The investor has some boundary conditions, such as maintenance costs, depreciation Rate, etc.; (4) The Design Institute determines the single tile cost (static and dynamic) and power generation according to the design plan. Based on the above conditions, calculate the economic returns under different financing models, determine the financing method and the maximum financing rate. Mode 6: Reverse calculation of single tile investment for investors to control investment level (1) The investor has an expected internal rate of return IRR for the entire investment or capital; (2) The investor has boundary conditions, such as loan ratio and interest rate, operation and maintenance costs, depreciation rate, etc.; (3) The investor has determined Grid-connected mode and operation mode. According to the above conditions, under the premise of the investor's expected revenue, a single-tile investment quotation is calculated and after deducting the project's initial development costs, it can also be used as the EPC quotation basis. This computational model is a commonly used method for real investment decisions. Grinding Tools,Cordless Grinding Tools,Electric Grinder Tool,Angle Grinder Machine ZHENGYANG TECHNOLOGY CO.,LTD , https://www.supraone.com
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