Influence of shadow occlusion on photovoltaic power station and its solution
In the design of photovoltaic power plants, we often encounter the problem of shadow occlusion where the photovoltaic modules are to be installed. When we encounter this problem, we need to find a suitable solution. So how do we solve this problem? Let's discuss together.
First of all, let ’s theoretically analyze the impact of shadows on the power generation of photovoltaic power plants. Before analysis, we should know that under normal circumstances, the shadows we say are caused by the buildings next to them. The shadows caused by dirt are different. The shadows caused by the buildings next to it cannot completely shade the light into the photovoltaic module. Generally, because the sunlight contains scattered light, even if there is obstruction, some light will enter the photovoltaic module.
The above figure is the output curve of the component under the occlusion ratio of 0, 25, 50, 75 and 100%, which is sequentially blocked by one of the cells. The component is formed by 54 cells connected in series. From this figure, we know that the blocking of a single cell will cause the shape of the output curve of the component to change, resulting in a decrease in maximum power, but the voltage and current at the maximum power point do not necessarily become smaller. The greater the blocking ratio, the greater the power loss.
The above figure is the output curve measured by a component with different bypass diode configurations. This component has 108 cells. The number of bypass diodes are: 2, 3, 4, 6, and the battery. The configuration mode of the slice is: 54 * 2, 36 * 3, 27 * 4, 18 * 6, 9 * 6. From this figure, we know that the more the number of diodes in the module, the less the power loss of the photovoltaic module caused by the shadow.
The above picture is the output curve measured by the same component when the position of the blocked cell is different. This component consists of 3 * 18 cells, A means normal, B means 75% of the light is blocked, 2A + B1 means that one cell is blocked, 1A + 2B1 means two cells are blocked, 3B1 means three cells are blocked, a in the figure above indicates that the blocked cells are in the same string, and b is blocked. Batteries in different strings. This figure shows that the number of blocked cells is the same, but when the position is different, the output power of the component is affected by the shadow block.
The above analysis shows that the influence of shadow occlusion on the output power of the photovoltaic module is not only related to the factors of the shadow itself (the ratio of blocking light, the blocking area, and the blocking shape), but also to the internal structure of the module. Therefore, it is very difficult to quantitatively analyze the impact of occlusion on the output power of photovoltaic modules. Moreover, the photovoltaic power generation system is connected by photovoltaic modules, and other devices can generate electricity. If the impact of shadow on the photovoltaic power generation system is more complicated, we can only summarize some qualitative laws to help us reduce as much as possible. The influence of shadow on the power generation of photovoltaic power generation system.
In actual engineering, we are more concerned about: how to calculate the shadow range? Especially when the obstruction is an irregularly shaped object and it is not in the south direction; if the shadow cannot be avoided, how can we reduce the loss of power generation as much as possible? In addition to affecting the output power of photovoltaic modules, will shadows cause safety problems? On this issue, I will discuss in detail in the next chapter.
Contact Person: Ms. Alice