This article briefly describes the relationship between the main points of installation of solar arrays and the generation of photovoltaic power generation systems, discusses the installation method and regular maintenance of solar arrays on the cement flat roof, and analyzes the difficulties in the maintenance of solar arrays. Solar cell array installation points █ Azimuth angle of solar cell array installation The azimuth angle of the solar cell array is the angle between the vertical plane of the square and the south direction (set the negative angle to the east and the positive angle to the west). Normally in the northern hemisphere, when the square is facing south (ie, the angle between the vertical plane of the square and the south is 0°), the solar battery power generation is the largest. When deviating from the south (northern hemisphere) by 30°, the power output of the square matrix will decrease by about 10% to 15%; when deviating from the south (northern hemisphere) by 60°, the power output of the square matrix will decrease by about 20% to 30%. . However, in the clear summer, the maximum time of solar radiation energy is after noon, so when the orientation of the square is slightly westward, the maximum generating power can be obtained in the afternoon. In different seasons, the time of peak daily radiation at each azimuth is different. The orientation of the solar cell array is slightly eastward or westward, with the largest amount of power generated. The arrangement place of the square matrix is ​​subject to many conditions. If the azimuth angle is to be adjusted so that the peak time of the load coincides with the peak time of the power generation in the day, the following formula can be referred to. Azimuth = (peak hour of the load in a day (24-hour clock) -12) × 15 + (longitude -116) █ The tilt angle of the solar cell array installation The square array of solar cells is usually placed facing the equator, and there is a certain inclination angle with respect to the ground plane, that is, the angle between the square plane of the solar cell and the horizontal ground. For fixed-cell solar arrays with uniform load throughout the year, if the radiation volume of the designed slope is small, it means that more solar cells are needed to ensure the power supply to the users; if the amount of solar radiation received by the solar cell s Large, it means that a lot of batteries are needed to guarantee the electricity supply in the month when the solar radiation is low. These will increase the cost of the entire system. Therefore, determining the optimal inclination of the solar array is an indispensable part of the wind-solar hybrid power generation system. In the design, it is hoped that the best tilt angle of the solar cell array will be obtained when the average annual power generation is maximum. The best tilt angle in a year is related to the local geographic latitude. When the latitude is high, the corresponding tilt angle is also large. . However, as with the azimuth angle, restrictions on the slope of the snowfall (slope is greater than 50% to 60%) must also be considered in the design. For slopes where the snow falls, even if the amount of electricity generated during the snow-covered period is small and the total annual power generation also increases, for positive south (with azimuth angle of 0°), the tilt angle is from horizontal (with a tilt angle of 0° degrees). When the gradual transition to the optimal angle of inclination begins, the amount of daily radiation continues to increase until it reaches a maximum value, and then the amount of radiation is continuously decreased as the tilt angle is increased. In particular, after the inclination angle is greater than 50° to 60°, the daily radiation amount decreases sharply until the final vertical placement, the power generation amount drops to the minimum. For situations where the azimuth is not 0°, the value of the daily amount of radiation on the slope is generally low, and the value of the maximum daily radiation is near the tilt angle close to the horizontal plane. For the selection of the solar cell array angle, comprehensive consideration should be taken in conjunction with the following requirements: 1) Continuity. The total amount of solar radiation in a year is generally continuous, most of which are monotonously elevating, and individual ones have a few ups and downs, but generally they do not fluctuate drastically. 2) Uniformity. Select dip angle, it is best to make the daily average amount of radiation received on the surface of the square array more uniform throughout the year, so as not to receive too much radiation in the summer, causing waste; and the amount of radiation received in the winter is too small, causing the battery to over discharge and even damage, Reduce system life, affect system power supply stability. 3) Greatness. When choosing the dip angle, it is necessary not only to obtain the maximum amount of radiation for the month with the smallest amount of radiation on the surface of the solar cell array, but also to take into account the annual average daily radiation dose not be too small. At the same time, specific analysis of specific situations is required. For example, some special loads (irrigation pumps, chillers, etc.) consume more power in summer, and the value of the solar cell array tilt angle should make solar cell arrays receive more radiation in summer than winter. A more approximate method can be used to determine the solar cell array tilt angle. Generally, in southern China, the inclination angle of the solar cell array can be increased by 10° to 15° more than the local latitude. In northern regions, the inclination can be increased by 5° to 10° more than the local latitude. When the latitude is large, the angle of increase can be smaller. In the Qinghai-Tibet Plateau, the dip angle should not be too large and can be roughly equal to the local latitude. At the same time, in order to facilitate the design and installation of the solar cell array support, the array tilt angle is often taken as an integer. The above is the relationship between the azimuth angle, the tilt angle and the power generation amount. For a specific design, the azimuth angle and the tilt angle of a certain solar cell array should be further integrated with the actual situation. For a fixed photovoltaic system, once the installation is complete, the solar cell array tilt angle and the azimuthal angle of the solar cell array cannot be changed. With the photovoltaic system installed with the tracking device, the solar cell array can follow the movement of the sun, so that the solar cell is always facing the sun, increasing the amount of solar radiation received by the solar cell array. However, currently there are relatively few tracking devices used in photovoltaic systems because the tracking devices are more complex, the initial cost and maintenance cost are higher, and the benefit of installing the tracking device to obtain additional solar radiation cannot offset the cost required to install the system. █ Influence of shadow on solar arrays Under normal circumstances, when calculating the amount of solar cell power generation, it is obtained on the premise that there is no shadow on the solar cell phalanx. Therefore, if the solar cell cannot be directly illuminated by sunlight, only scattered light is used to generate electricity, and the power generation at this time is reduced by about 10% to 20% compared to the case without shadow. For this situation, correct the theoretical calculations. In general, when there are buildings and mountain peaks around the solar array, there will be shadows around buildings and mountains after the sun comes out. Therefore, you should avoid shadows when selecting a location where solar arrays are installed. If it cannot be avoided, it should be resolved from the wiring method of the solar cell so that the influence of the shadow on the power generation amount is minimized. In addition, if the solar cell array is placed before and after, after the distance between the rear solar cell array and the front solar cell array is close, the shadow of the front solar cell array will affect the power generation of the rear solar array. . When the latitude is high, the distance between the square arrays of the solar cells should be increased, and the area of ​​the corresponding setting place will also increase. For the squares with anti-snow-covering measures, the tilt angle is large, so that the height of the solar cell array is increased. To avoid the influence of shadows, the distance between the solar cell arrays is also increased accordingly. Generally, when arranging the solar cell arrays, the structure size of each solar cell array should be selected separately, and the height thereof should be adjusted to an appropriate value so that the height difference can be used to minimize the distance between the solar cell arrays. The specific design of solar cell arrays, in the rational determination of azimuth and tilt angle, should also be fully considered in order to achieve the best state of the solar cell array. Solar cell array installation The solar cell square array bracket is used to support the solar cell square array, and the structural design of the solar cell square array must ensure that the connection between the solar cell square array and the bracket is firm and reliable, and the solar cell square array can be easily replaced. Brackets and other required materials (such as bolts, etc.) should be made of durable, rust-proof and UV-resistant materials. Solar arrays and brackets must be able to withstand 120km/h of wind without being damaged. In the installation of the solar cell array support, all the array fasteners must have sufficient strength to reliably fix the solar cell array on the support. Solar arrays can be installed on roofs, but the supports must be connected to the main structure of the building and not to roofing materials. For ground-mounted solar cell arrays, the minimum distance between the solar cell array and the ground should be 0.3m or more. The bottom of the column must be firmly attached to the foundation so that it can withstand the weight of the solar array and can withstand the design wind speed. One of the issues that needs to be taken seriously in the design of the solar cell array is the wind resistance design. According to the technical parameters of solar cell array manufacturers, the solar cell array can withstand wind pressure of 2700Pa. If the wind resistance coefficient is chosen to be 27m/s (equivalent to a tenth-class typhoon), according to the non-viscous fluid mechanics, the wind pressure experienced by the solar cell array is only 365Pa. Therefore, the assembly itself can withstand wind speeds of 27m/s without damage. Therefore, the key considerations in the design are the design of the solar cell square bracket, the basic design, and the design of the connection between the bracket and the foundation. The connection design of the solar cell array bracket and the foundation should use the bolt rod fixed connection method. The component mounting structure must withstand environmental stress such as wind and snow, the mounting holes must be easy to install and adjust, and must withstand certain mechanical stress. Using the correct mounting structure materials can minimize the corrosion of the assembly frame, mounting structure and materials. Solar cell array work should be installed in the direction to ensure maximum exposure to sunlight, taking into account changes in the direction of the incident light within a day and within a year of the winter and summer solar distance from the horizon height. In general, the components should be installed in an inclined manner towards the equator, that is, the light-receiving surface of the components of the northern hemisphere should face the south, and the light-receiving surface of the components of the southern hemisphere should face the north. In general, the angle between the component and the ground should be ±5° to 10° from the local latitude. The solar cell array checks the building code used during installation on the roof to ensure that the building and its structure (roof, exterior, load-bearing, etc.) required for installation of the assembly have sufficient loading capacity. When installing the components, make sure that the components are installed on the fireproof roof and the roof is inclined less than 5 in/ft to ensure its fire rating, and that it is securely secured and not damaged by strong wind or heavy snow. When the roof is installed, the roof that needs to be penetrated when installing the fixing component should be properly sealed to prevent the leakage of the roof. The bracket for installing the solar cell array on the cement flat roof can be divided into two parts, one is the base part of the bracket and the other is the bracket part. The base of the bracket is cast from a concrete named C30, and the base (cement pier) of the bracket is arranged as shown in FIG. 1. When the wall is too high or there are obstacles on the ground (lightning belts, conduits, bridges), it is possible to use a stand with raised feet. The roof can also be laid in double rows. The back of the solar array must ensure smooth ventilation (components and mounting surfaces. The minimum interval is 10cm). The brackets produced by different manufacturers are different, and the brackets applied according to the unique conditions of the site are also different. The schematic diagram of the installation of the self-heavy bracket on the cement plane roof is shown in FIG. 2 . Regular maintenance and maintenance difficulties of solar cell array █ Regular maintenance of solar cell array The use and maintenance of solar cell arrays directly affects the service life of solar cells, affects the operating costs of solar power systems, and affects the efficiency. The maintenance of solar cell arrays is the best means to maintain a good system operation. Under normal circumstances, there is no need for surface cleaning of the solar cell array, but the exposed wiring contacts must be checked and maintained regularly. 1) In the event of strong winds, heavy rain, hail, heavy snow, etc., measures should be taken to protect the solar array to prevent damage. 2) The solar cell array lighting surface should always be kept clean. If there is dust or other dirt, it should be rinsed with water first, and then wipe it dry with clean gauze. Do not wash with hard objects or corrosive solvents. ,wipe. 3) Periodically check the wiring of the solar array's electrical system to avoid loose wiring. 4) Periodically check the grounding resistance of the solar array. When the solar cell array is installed in an environment where the air is often dusty, regular observations should be made on the solar cell array. When observing that the surface area of ​​the solar cell array is dusty gray, the original blue of the solar array cannot be seen clearly. In the case of a crystal-like board surface, the solar battery matrix should be promptly cleaned and dust-removed. In order to avoid insufficient absorption of light by the square array of solar cells, the battery is insufficiently charged, thereby affecting the service life of the battery. Use a safety ladder to remove dust during dust removal. Do not directly climb the solar cell array mounting bracket. You can use a clean, dry cotton mop to remove dust and then use a wet, clean cotton mop to clean it. █ Maintenance difficulties of solar cell array As the quality of solar cell arrays cannot be controlled, the life cycle cannot be guaranteed. The life of a solar cell array depends on the package form. Qualified solar cell arrays that are manufactured strictly using lamination processes can have a service life of 25 to 30 years, but at present most of the solar cell arrays produced in China use epoxy resins. “Epoxy†encapsulation, under the irradiation of sunlight and ultraviolet light, the epoxy resin will yellow and white, and the lifespan of the solar cell array is only 1 to 2 years. Even if the improved epoxy resin can make the lifespan more than 2 years, Still can not meet the requirements of use, and some even do not reach the "energy recovery period." Even if some solar cell arrays are laminated, these solar cells use poorly transmissive ordinary glass and poor packaging materials such as EVA, plus they are not packaged in strict accordance with the process requirements and their service life exceeds 4 to 5 years. Not much; The solar cell array consists of a plurality of solar cells. If a single solar cell is isolated during the process of use, such as bird droppings, leaves, etc., the solar cells are individually shielded from heat and damage under strong sunlight. Therefore, the entire solar cell array is damaged. This is the so-called heat island effect. Even if the solar cell array is tilted and anti-bird pins are installed, the attachment of leaves, bird droppings, or other obstructions cannot be completely prevented. This requires the staff to frequently clean the solar panels. In addition, it is necessary to periodically check the tightness of all the mounting parts and meet weather conditions such as hail, squally wind, and heavy rain, and use protective measures in time. Stainless Steel Rod,Stainless Steel Bar,Metal Rod,SS Rod Torich International Co.,Ltd--The Steel Tube Maker , http://www.chinasteeltubepipe.com
