Vigorously developing clean energy has become the consensus of governments around the world, among which photovoltaic power generation is the most easily promoted clean energy, and it can effectively use space. Small photovoltaic power generation systems often require lithium battery energy storage systems, because it can effectively store unstable energy, and at the same time can obtain the highest profit value for customers: it is released when the grid needs electricity most, that is, when the price of electricity is the highest. maximum energy.

　　SES Power has more than ten years of rich experience in lithium battery energy storage systems. For example, our energy storage products use square aluminum-shell lithium iron phosphate batteries that can perfectly replace lead-acid batteries. These products can be used in power and energy storage applications, the maximum current reaches 2000A output, the voltage covers 12V to 560V, and the capacity ranges from 1KWh to 1MWh, covering lead-acid replacement, industrial supporting, UPS, RV, solar energy storage, home energy storage and other fields. Similarly, we also provide customers with a full range of services for energy storage systems, of which photovoltaic power generation is one of them, so we have professional knowledge in photovoltaic power generation. Let the senior engineer of SES Power explain to you how to optimize the inclination angle of photovoltaic power station. It is very important because it can greatly affect the efficiency and upper limit of photovoltaic power generation.

　　1. What is the optimum inclination angle?

　　The angle between the surface of the photovoltaic module and the surface level is called the inclination angle.

　　The earth revolves around the sun all the time, and the direct sunlight point moves back and forth between the tropics of the earth in one revolution period. Therefore, the total amount of radiation received by the surface plane of photovoltaic modules at different inclination angles is different. When we design the power station, we generally refer to the historical data of accumulated radiation throughout the year at different inclination angles, and select the angle with the highest radiation amount as the best inclination design.

　　If the annual total radiation received by the inclined surface of the fixed photovoltaic array is the largest at this inclination angle, the inclination angle is called the optimal inclination angle (instead of the highest annual power generation); however, in some scenarios, the optimal inclination angle is also It can be the inclination angle corresponding to the highest annual power generation, the inclination angle corresponding to the highest yield, the inclination angle corresponding to the highest power generation in certain months, and the optimal inclination angle calculated under various other limited conditions. This paper mainly discusses the inclination angle with the largest annual total radiation amount.

　　2. Why is the optimum inclination needed?

　　The optimal inclination angle is designed, mainly to receive more solar radiation.

　　For a photovoltaic square array slope, the different incident angles of the sun on it will lead to different amounts of solar normal radiation received per unit area. The larger is, the less solar normal radiation is received (for the same radiation input). The change of the inclination angle of the photovoltaic array will change the incident angle of the sun and affect its radiation reception. Therefore, it is necessary to obtain an optimal tilt angle based on the radiation received from the whole year through theoretical calculation.

　　(Schematic diagram of module receiving solar radiation)

　　In the actual process of designing the optimal inclination angle, factors such as the geographical environment and natural environment of the project construction site should also be considered. For example, the influence of the inclination angle on snow falling; the influence of the wind pressure and snow pressure resistance of the modules when the inclination angle changes; at the same time, the influence of these factors on the selection of photovoltaic support materials and foundation weight, as well as the distance between the front and rear rows caused by the high angle, must be considered. change, increase the cost of land use, etc.

　　3. How to calculate the optimal inclination?

　　The calculation of the optimal inclination requires the local longitude and latitude to determine the altitude and azimuth of the sun at each moment, and the average annual radiation data for many years to determine the characteristics of the local solar radiation.

　　According to the radiation data and latitude and longitude calculation, the total annual radiation reception of photovoltaic arrays with different inclination angles is accumulated, and the inclination angle with the largest annual total radiation amount is selected as the optimal inclination angle. Generally, software such as PVsyst can be used to calculate the optimal inclination angle conveniently and quickly.

　　To compare the influence of different inclination angles on power generation, a single variable should be used for comparison. However, in general, the inclination angle of the components of the same power station is the same angle and orientation, and there are many factors affecting the comparison of power stations in different regions. Therefore, it is considered to use the PV-System design software to demonstrate it, because its meteorological data comes from NASA and Meteonorm meteorological databases. At the same time, through actual measurement, its measurement accuracy is as high as 99%, which is for reference.

　　4. What factors affect the optimal inclination angle?

　　The main influencing factors include: ① Latitude, the difference of latitude will affect the variation characteristics of the solar altitude angle, thus affecting the optimal inclination angle; ② The monthly radiation amount distribution, if the radiation amount in a year is more concentrated in the high solar altitude angle. The month will make the optimal inclination angle larger, otherwise it will become smaller; ③ the direct-scatter ratio, the direct radiation is directional, while the scattered radiation is isotropic, so their respective proportions in the total radiation are different, which also affects the optimal inclination angle. have a certain impact.

　　5. Is the power generation of the photovoltaic power station the highest under the optimal inclination angle?

　　According to the design sequence of the photovoltaic power station, first determine the optimal inclination angle (the mutual occlusion between the arrays is not considered at this time), and then determine the north-south spacing of the photovoltaic array according to the inclination angle. Influenced by shadow occlusion, the radiation amount of the inclined plane and the power generation capacity of the power station are dynamically determined by two factors: the distance and the inclination angle, so there will be a slight gap between the inclination angle of the maximum power generation amount and the optimal inclination angle, but unless there are other restrictions, Usually the difference between the two is not too big.

　　6. Is the revenue of photovoltaic power station the highest under the optimal inclination angle?

　　The optimum inclination angle means high radiation reception, but also means a relatively large footprint.

　　For example, in a limited site area, as the optimal inclination angle decreases, the installed capacity will continue to increase. Decreasing the inclination angle will reduce the power generation, and increasing the installed capacity will increase the power generation. Therefore, the final inclination angle under which the profit is the highest will require further technical and economic comparisons based on external conditions to determine. Generally, the installation angle of the cement flat roof is recommended to be greater than 10 degrees, which is conducive to the self-cleaning of the components by rainwater.

　　7. Is the optimum inclination absolute?

　　Due to the uncertainty of climate, the optimal dip angle can only be called the relative optimal dip angle based on historical data.

　　First of all, the optimal inclination angle is different with different historical radiation data. There are some differences between the optimal inclination angle calculated with historical 5-year data and 10-year historical data; A great possibility, but for a certain year, it may not be the best choice.

　　Finally, through the above analysis and past experience, SES Power can summarize the following points:

　　(1) The optimal tilt angle is related to the local geographic latitude. Taking the equator as the reference point, as the geographic latitude gradually increases toward the earth's poles, the corresponding optimal inclination angle gradually increases.

　　(2) When the inclination angle increases from the horizontal (0°) to the optimal inclination angle, the amount of radiation received by the surface increases accordingly. When the optimal inclination angle is reached, the amount of radiation received is the largest; as the inclination angle continues to increase, the surface receives the maximum amount of radiation. The amount of radiation received begins to decrease again, and the corresponding power generation decreases gradually.

　　(3) The inclination angle is within the range of ±5° of the optimal inclination angle, and the influence of radiation on the power generation is relatively small.

　　(4) Whether to design the optimal inclination angle needs to be comprehensively evaluated according to the installation site conditions and the economics of the scheme, and should not be designed blindly.

　　(5) Photovoltaic power generation is only a link in the energy storage system. When a lithium battery system is required for use, it is recommended to choose a senior high-quality service provider like SES Power for consultation.