光伏系统因安装设计不合理造成的损失（The pv system caused by improper installation design）

光伏系统因安装不合理造成的损失（The pv system caused by improper installation design） 光伏系统因安装设计不合理造成的损失(The pv system caused by improper installation design) At present, the problems and disadvantages of the pv system in the residential and commercial grid system have many shortcomings in the technology of grid pv system. The purpose of this paper is to discuss and classify the problems and drawbacks inherent in residential and commercial pv systems. Typical residential photovoltaic installations are suffering from many problems that prevent us from fully exploiting the market potential of this technology. Many of the current problems stem from power losses - whether or not they are mismatched or partially obscured by a module mismatch. Other problems lie in the lack of monitoring and analytical capability in system design. In addition, safety and other issues constitute the risk that workers will install or maintain fire crews to deal with fire near the solar plant system. For the distributed SolarEdge power collection system, the SolarEdge paper "SolarEdge architecture overview" is used to overcome the limitations of traditional systems. Typical system architecture currently residential pv systems usually have 10 to hundreds of photovoltaic modules connected to a series parallel connection as shown in figure 1. Typically, a few panel modules from 10 to 15 are connected to a string to achieve a voltage/dc/ac transformation of up to 800v high of 150V. You can add pv to the system to get more energy. Because of the connection string, they must conform to all the parameter lengths and type directions of the other string. The whole array is connected to a solar converter that collects electricity and inverts it to the grid. The inverter tracks the maximum power points of the entire array. This is the maximum power obtained from the array by finding the dc working point. The harvested power is changed from dc to ac power and fed to the grid. The inverter is also responsible for compliance with electrical and safety regulations. The defects of photovoltaic power generation system are discussed in part to discuss the different typical pv systems and other major shortcomings of these systems. In the process of photovoltaic cell production, the module mismatch loss is very different from each battery in the output capacity. To reduce the difference between the cells in the same module, they are classified at the time of manufacture and the same module USES the same battery. This will reduce the difference in output power of the panel. The groups themselves do not have a sort in the current market where the output power has a margin of error of about 3. When multiple modules are in series each module has a slightly different MPP current. The series group does not allow the best MPP to come from the current individual modules themselves. The inverter will select an electric current to achieve the average peak power point of a series or group. The peak power is always less than the sum of the peak power points of each module. Figure 2 shows the power curve of the i-v and 3 mismatch modules. The power curves of i-v and these modules are shown in FIG. 3. This is obviously the peak power point of the string is different from the combined peak power of the three modules. The loss shown here is referred to as the mismatch loss. It can be as high as 5 in standard residential and commercial photovoltaic installations. Partial cover loss when a group or group has a shadow that causes a partial occlusion to cause a different intensity of light on the battery on the panel. This can happen from light obstacles such as dirt and snow from the chimney of the building itself. Shading will reduce a portion of the output of any component, but this reduction will vary depending on the component's electrical configuration. Obviously any battery or module that has a shadow will be reduced because the intensity of the light will go down. However, since this has a shadow battery or a module that is electrically connected to other cells and a non-shaded module the performance will be reduced because this is basically a mismatch. For example, if there is a partial shadow in a single module, the output current will decrease, which can determine the working point of the whole string. In addition, it can be used as a module to stop the production power of the module. Part of the shaded crystalline solar cell component will lead to a significant reduction in the output of solar cell components. A fully screened module can reduce the output of solar cell components from 40 to 95. If a few modules are blocked, the voltage of the open circuit may be lower than the voltage at the open circuit, which leads to the string to the group without contributing output. The output of the series with occlusion decreases far more than the output from the reduced area of illumination. This is since the output of the shaded part is through the shaded part in are seriously blocked and unable to maintain the working voltage of the string in the output of the battery has a light reduce and keep the working voltage of the module of power because it did not work in their respective peak power point. For the housing system, it is impossible to prevent all sunshades from being avoided because there are no strict limits on the size of the array so that the output can be lost at any time. Some of the sunshade losses in these systems are estimated to be between 5 and 25 per year. The performance of the MPP of M efficiency loss is a very important characteristics of the pv systems for photovoltaic system such as other system must be based on renewable energy in every moment gather the largest available energy from renewable resources. The macro efficiency of MPPT algorithm is whether it can make the inverter work at the maximum power point MPP. In order to achieve this goal, MPPT algorithm can accurately track the changes of MPP, such as the variation of the light temperature factors. Obviously the amplitude and variation and dynamic MPP system can seriously affect the accuracy. The loss of MPP system occurs due to two main factors, 1. Static loss causes MPP algorithm to locate the peak power point of the array. In some cases, the MPPT algorithm can lock local maximum values. 2. The dynamic loss causes MPPT algorithm to track the change of peak power points at the appropriate speed. The main reason for the static loss of pv system is the peak of the component's power curve. Shadow shading causes the array of power curves to show multiple maximum power points. More specifically, two or more peak power points out that different modules run at different peak power points on the current curve. Most MPPT algorithms are not designed to be effectively located at the peak of the local peak and the maximum power tracking efficiency of the local peak is significantly reduced. Figure 5 shows the MPPT efficiency of four different inverters in the static measurement. The results show that different losses are between 1 and 10. Dynamic loss and tracking speed are directly related to the accuracy of MPPT algorithm. The change in peak power points is caused by changes in the intensity of light. These changes are slow and monotonous when the cloud is cloudless and they can change faster in some atmospheric conditions. Figure 6 shows two consecutive days of measurements in Spain. The first day corresponds to a sunny day with some cloud cover at the end of the day. The next day corresponds to changes in atmospheric conditions. The graph shows the evolution of the maximum power point of pv cells in the two days to measure the curve of the i-v characteristic. With this information, you can calculate the actual maximum power of MPPT in these days. This is compared to the energy collected by the leading photovoltaic inverters in the market. Figure 7 shows the theoretical energy compared to the energy collected in the first sunny day. The chart shows that the MPPT algorithm is pretty good at tracking the most power points for most of the day. But in the last part of the day, the red circle was not tracked to the maximum power point of the power generation due to the partial shadow of the weather. In these hours, the maximum power tracking efficiency of MPPT algorithm is 96 or 4. The loss is due to the fact that MPPT algorithm cannot handle this real life scenario. Figure 8 shows the results of the second day. The day is cloudy and the light changes quickly due to atmospheric conditions. The maximum power tracking efficiency of the inverter is reduced to 95. In addition to previous discussions on power loss, the system design and the roof pose a major challenge to system installation and designers. The following factors cause the system to be seldom optimized and in many cases one less than expected, and the cascade voltage is subject to the minimum and maximum allowable voltage limit for inverters. 2. Parallel placement must have the same length in combination with physical constraints of specific geography and roof. When designing the system, the installer must take into account the maximum input voltage of the inverter and ensure that the voltage cannot reach the maximum voltage under the most extreme opening conditions. This is difficult because many parameters such as voltage error temperature change and sunlight must be taken into account. On the other hand, the minimum input voltage of the inverter must be kept at any time to obtain the power. Taking into account changes in the same parameters and partial shadows in the possible strings make things more complicated. In some cases, these constraints result in low utilization of the roof. There are a number of record events that indicate that the installer USES a short string to increase the utilization of the roof to make the system less voltage in the summer. The roof use problem is more dramatic. The irregular shape of the roof of the commercial roof and the additional obstacle units in the air vents of the chimneys have increased the difficulty of selecting only one string length. The average commercial roof utilization ratio of 65 to 70 is due to the problem with the roof. The multi-directional roof poses another challenge for the photovoltaic system. In this case multi-purpose inverter can better utilize the surface of the roof. For example, installing 2 faces on the roof of the roof will require two inverters or a multi-input inverter. These two solutions reduce costs. It is clear that the serial parallel architecture has caused many constraints to the pv system and prevented the full utilization of the roof to reduce the actual energy harvest of the system per year. The inherent problem of system feedback and troubleshooting another series of parallel connections is that each element in the correct installation and operating system cannot be verified. The only measurable data points in the inverter input voltage input power can only partially assist in evaluating system performance. Due to the fact that a major problem in the overall output power monitoring installation may not be found, it may cost the owner 10 or more of the energy feedback. There is no operational diagnostic information when dealing with operational problems, the only option is to be suspected of scheduling technicians on the Internet without head and head. This search becomes more difficult when the installation volume increases. The largest commercial photovoltaic website in California was installed in 2004 with 1,000 solar cell components that made the problem very real. In some cases, the detection of the unconnected string is also hindered by the detection of the defective module. For example, in an eight-string system, 12.5 power loss detection is the equivalent of a bunch of non-trivial things, especially because the expected output power of the system is related to all of the other criteria mentioned above. Even when a failure is suspected and the technical personnel are sent to the site, it is expensive because it requires skilled technicians to deploy at the solar site. Once in the scene their only solution is to dismantle the system and find out the cause of the failure. The same lack of feedback has also increased the initial installation time due to long verification and debugging. Another drawback of the transformation and long-term fault-tolerant pv system is that it is difficult to transform and replace failure modules throughout their lifecycle. If pv modules in the damage due to extreme weather or accidents while installing it must be replaced by the module of similar electric property and because of the photovoltaic modules has been developing so impossible for a new replacement photovoltaic modules in an old installation. For this reason, the photovoltaic company maintains a battery and module inventory for 25 years to supply the old system. The same reason to prevent old systems from reinventing you is basically limited to old technology. The safety of system safety system has always been concerned. Over the years, many codes and standards have been developed and discussed to improve the security of these systems. The two main security issues remain the risk of electric shock when installing the system. Even if two tandem modules are exposed to the sun, there will be enough voltage and electrical contact. During the installation process, there are many procedures and security measures that slow down the process but keep employees safe. 2. The fireman was in danger when a fire broke out. The first thing a fireman does is cut off the building power. This allows them to use sprinkler shafts to cut the smoke out of the roof. These actions are dangerous when the photovoltaic system is installed on the roof. Firemen training to cut off power. After doing so they believe that there is no electricity to endanger them. The terminal voltage of the component is not removed after the photovoltaic building is cut off. Firefighters are preparing to cut a hole in the roof or use water that could be electrocuted. Regulators and fire officials are pushing for new rules to ensure that photovoltaic modules are cut off when a fire breaks out. Conclusion we introduce the structure of pv system and some disadvantages and disadvantages in design and construction. While previous efforts have focused on improving the various aspects of photovoltaic power generation systems, no comprehensive approach has been proposed to address the many problems existing in photovoltaic systems. SolarEdge distributed power supply system is the only energy collection system and the architecture provides a powerful solution can complete the energy collected by 25 in this file describes how to resolve the problem.