In photovoltaic power plants, whether the components are arranged horizontally or vertically is a common problem. In the past, there have been many articles on this: According to the characteristics of the component bypass diode setting, when some components are blocked by the front row components, the lateral arrangement of the components is vertically arranged relative to the components, which can retain more power generation. ability. After the bottom row of cells in the horizontally arranged component is blocked, due to the presence of the bypass diode, the affected cell for this battery component has only 20 of the lowermost loops, and 40 of the upper two loops The sheets are unaffected; while the vertically arranged components are in this case all of the cells are affected.
So after knowing this phenomenon, we will hope to know further what the difference is. In the previous online article, some people have done experiments. When the laterally arranged components lose about 20% of power under the same occlusion ratio, the vertically arranged component losses have exceeded 90% and are close to 100%.
From this result, the difference between the two schemes is very large, but this experiment is only for the local time point. What we want to know more is how much this difference affects the power generation in a year for the entire PV plant. Considering that the actual occlusion time before and after the occlusion is at a low radiation time, the process from partial occlusion to total occlusion will not last too long, so it is certain that the actual power generation difference should not be too large. However, it is not realistic to find two external conditions, and it is not realistic to use a photovoltaic system with a horizontal arrangement of components and a vertical arrangement of components for one year. Therefore, it is considered to be a relatively easy way to compare using photovoltaic system simulation.
The simulation of the PV system is carried out using PVsyst software. Assuming the project site is Beijing, a 50kW string inverter and its connected component string are observed in the system. The string inverter is connected to 8 components. String, each component is connected in series of 22 blocks.
With 35° solar panel racking installation inclination, each PV solar mounting bracket is installed with two strings, a total of 44 components, which are arranged in horizontal arrangement and vertical arrangement. The horizontal arrangement adopts 4×11 arrangement, and the vertical arrangement adopts 2×22. Arrangement. The north-south spacing is calculated according to the formula in GB50797-2012, and is not enlarged or reduced.
The blue color in the figure is the PV solar module mounting area to be compared and compared. There are 4 groups of 4 brackets in total; the red area indicates other PV arrays around it. These arrays only serve as obstructions and do not receive radiation. The model dimensions of the horizontal arrangement and the vertical arrangement of the components are different from the north-south spacing, and the other solar panel mounting structures are the same.
To simulate the horizontal and vertical arrangement of the components, it is necessary to simulate the three bypass diodes accurate to the component, so the Modulelayout must be set in PVsyst when modeling.
Two schemes are used in Modulelayout: 4×11 component horizontal arrangement (Fig. 3) and 2×22 component vertical arrangement (Fig. 4). Because of the string inverter, for the sake of fairness, Both schemes adopt a series connection method of upper and lower columns, and the above group strings are connected to the same MPPT, and the following group strings are connected to another MPPT.
After the setting is completed, the shadow simulation is performed to calculate the power generation amount, and the output power of the photovoltaic array is taken as the comparison object in the final calculation result, and the output result is as follows:
From the simulation results, the horizontal and vertical arrangement of the components does produce a certain difference in power generation, but in the case of the same external conditions, the difference between the two is not large. Therefore, in the optimization of the scheme, if the conditions permit, the horizontal arrangement can be selected; but if there are other factors, such as brackets, terrain, etc., it is not necessary to insist on the horizontal arrangement.