Power generation is the cornerstone of photovoltaic power plants. Power stations with the same capacity may have much different power generation. How does the difference in the power generation capacity of the power station come about? What factors will have a large impact on the power generation of the system?
PV modules are the only source of electricity generation
The module converts the energy radiated by sunlight into measurable direct current electricity through the Photovoltaic effect. Without components or the capacity of the components is not enough, no matter how good the inverter is, there is nothing that can be done, because the inverter cannot convert air into electricity. Therefore, choosing suitable and high-quality module products is the best gift for the power station; it is also an effective guarantee for long-term stable income.
The string design is critical. The same number of components is used in different string methods, and the performance of the power station will be different. The rated working voltage of the three-phase inverter is generally around 600V. If the string voltage is low, the boost circuit operates frequently, which will have a certain impact on the efficiency. Taking 56 pieces of 445Wp monocrystalline silicon modules with a 20KW inverter as an example, the power generation of the string method is higher than that of the string method.
The laying and installation of components is crucial
With the same module capacity in the same installation site, the orientation, arrangement, inclination of the module, and whether it is blocked will have an important impact on the power. The general trend is to install in the south. In actual construction, even if the original state of the roof is not south, many users will adjust the bracket to make the module face south as a whole. The purpose is to receive more light during the year. radiation.
In principle, different latitude regions require the installation inclination of the modules to be close to or greater than the local latitude value, but it should also be carried out according to the actual situation and cannot be implemented mechanically. The load on the roof, wind resistance, wind, rain and snow in the year and other climatic factors should be considered. For larger rooftop power stations, it is recommended to use a smaller inclination angle, and the distance between the component square array and the building roof should not be too large and appropriate, so as to avoid the distance between the end of the square array and the roof being too large, which may cause potential safety hazards. According to the actual lighting time, you can choose west or east, because in these areas, the light starts very early or the west light lasts for a long time, and the installation is inclined to make the most of the situation, so that the modules can receive light for a longer time, so as to continue to produce electricity.
In addition, various possible occlusions are always a factor that needs to be avoided in the installation of components. It can even be said that occlusion is the biggest killer that affects the power generation. If only half of the modules in a string are blocked due to shading, there is almost no current. Therefore, during the installation phase, try to avoid obvious or potential shading.
Grid fluctuation factors must not be ignored
What is "grid fluctuation"? It is the situation that the voltage value or frequency value of the power grid changes too much and too frequently, resulting in unstable power supply to the load in the station area. Generally, a substation (substation) needs to supply power loads in many areas. Some terminal loads are even tens of kilometers away, and there is loss in the transmission line. Therefore, the voltage near the substation will be adjusted to a higher level. In these areas, grid-connected photovoltaics The system may be in standby because the voltage on the output side is raised too high; or the photovoltaic system integrated at the remote end may stop working due to a system failure due to a low voltage. The power generation of the photovoltaic system is a cumulative value. As long as it is in standby or shut down, the power generation cannot be accumulated, and the result is a reduction in the power generation. At the same time, the photovoltaic market has continued to boom in recent years. In some areas where the mains voltage was normal, the voltage of the photovoltaic system in the same area increased due to the large proportion of the photovoltaic system capacity, and the absorption capacity in the area was limited. These photovoltaic systems It also faces the problem of grid fluctuations. The most intuitive impact of power grid fluctuations is that the power generation curve fluctuates frequently, so that there is no output when generating power. In this way, compared with a power station with a smooth and rounded power generation curve, the power generation will inevitably be less.
MTBF
Originally, this concept was aimed at electrical products, but there is more than just an inverter in the photovoltaic system. This concept can also be borrowed here, that is, the longer the time interval between failures of a photovoltaic power station, the more stable the power station’s operation. The longer the stable time, the more stable the work can be maintained for a long time, which can naturally bring stable power generation income.
The faults of photovoltaic power plants include a wide range of contents, not just the faults reported by the inverter. The grid fluctuation mentioned above is actually a fault. In addition, such as snow and dust on the components, PV reverse connection Virtual connections, aging and loose AC and DC cables, power company maintenance and power outages, virtual connections in the AC distribution box, trips that are not restored, etc., all belong to this scope.
Any problem in any link will cause the power station to fail to connect to the grid for power generation or restore power generation to the grid; the end result will still lead to low power generation. Therefore, after installing the photovoltaic power station, in the process of automatic operation of the system, it is necessary to arrange regular inspection operation and maintenance, to grasp the dynamics of all aspects of the power station in real time, to eliminate the unfavorable factors that may affect the mean time between failures of the power station in time, and to ensure the stable output of the power station.