1. What is the best angle of inclination? In a narrow sense, if the total annual radiation received by the fixed photovoltaic array on the inclined surface is the largest at this inclination angle, the inclination angle is called the optimal inclination angle (according to the "Photovoltaic Power Station Design Specification" GB50797-2012, the optimal inclination The inclination angle is defined as the largest total annual radiation, not the highest annual power generation); however, broadly speaking, the best inclination angle can also be the inclination corresponding to the highest annual power generation, the inclination corresponding to the highest rate of return, and the highest power generation in a few months The corresponding inclination angle and the optimal inclination angle calculated under various other restricted conditions. The following discussion is mainly based on the best inclination angle in the narrow sense that everyone often talks about. 2. Why do we need the best angle of inclination? In order to receive more solar radiation. For the slope of a photovoltaic array, the difference in the angle of incidence of the sun on it will result in a different amount of solar normal radiation received per unit area. The angle of incidence (the angle perpendicular to the normal of the photovoltaic array) The larger the amount, the less the amount of solar normal radiation received (for the same radiation input). 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 inclination angle from the perspective of the annual radiation reception through theoretical calculations, and this inclination angle is the optimal inclination angle. 3. How to calculate the best inclination angle? The calculation of the optimal inclination angle requires the local latitude and longitude to determine the altitude and azimuth angle at each moment of the sun, and annual radiation data, preferably multi-year average annual radiation data, to determine the characteristics of the local solar radiation. According to the radiation data and the latitude and longitude, the annual total radiation reception of the photovoltaic array with different inclination angles is calculated and accumulated, and the inclination angle with the largest annual total radiation is selected as the best inclination angle. Generally, software such as PVsyst can be used to calculate the best inclination easily and quickly. 4. What are the main factors affecting the optimal inclination angle? The main influencing factors of the optimal inclination angle include: ①The difference in latitude and latitude will affect the change characteristics of the solar altitude angle, thereby affecting the optimal inclination angle; ②The monthly radiation distribution, if the radiation in a year is more concentrated in the sun Months with high altitude angles will make the best inclination angle larger, and vice versa; ③Direct dispersion ratio, direct radiation has directivity, while scattered radiation is isotropic, so their respective proportions in the total radiation are also different. It has a certain influence on the optimal inclination angle. 5. Does altitude affect the optimal inclination angle? The effect of altitude on the optimal angle of inclination is described in the public historical article "Does altitude affect the optimal angle of inclination?" 》There is a more detailed explanation, please refer to it. 6. Is the photovoltaic power station's power generation always the highest under the optimal inclination? It is not the best inclination angle in the narrow sense. According to the order of "Design Specification for Photovoltaic Power Stations", the best inclination angle is determined first (the mutual shielding between the arrays is not considered at this time), and then the north-south spacing of the photovoltaic array is determined according to the inclination angle. When the distance is determined, there will be shadow occlusion between the front and rear photovoltaic arrays. At this time, the radiation amount of the slope and the power generation of the power station are dynamically determined by the distance and the inclination angle, so the maximum power generation inclination angle and the optimal inclination angle There will be a slight gap between them, but unless there are other qualifications, generally the gap between the two will not be too big. 7. Will the photovoltaic power station have the highest profit at the optimal inclination angle? It is not the best inclination angle in the narrow sense. Sometimes an angle less than the best inclination angle has higher benefits. The best inclination angle means high radiation reception, but it also means a larger footprint. For example, in a limited site area, as the optimal inclination angle decreases, the installed capacity will continue to increase. A decrease in the inclination angle will reduce the power generation, and an increase in the installed capacity will increase the power generation. Therefore, the final inclination angle at which the profit is the highest will need to be determined by further technical and economic comparisons in conjunction with external conditions. 8. Is the best angle of inclination absolute? No, due to the uncertainty of the climate, the optimal inclination angle can only be called the relative optimal inclination angle based on historical data. First, the historical radiation data is different, the optimal inclination angle will also be different. There are some differences between the optimal inclination angle calculated using historical 10-year data and the optimal inclination angle calculated using historical 20-year data; secondly, the historical average data represents a part of the local radiation characteristics. This is a great possibility, but for a certain year, it may not be the best choice.