In the photovoltaic power generation system, the choice of the inclination angle of the photovoltaic modules directly affects the power generation of the photovoltaic power generation system. The determination of the module installation inclination is the key to obtain the maximum power generation of the system.
(1) Geographical analysis
The choice of photovoltaic power station site has a very important impact on the cost of power generation. The unreasonable selection of photovoltaic power station site will directly cause the loss of photovoltaic power generation capacity and the increase of maintenance costs, the overall benefit and operating life will be greatly reduced, and may also have an impact on the surrounding environment. Therefore, the location selection of photovoltaic power stations is particularly important.
(2) Arrangement of meteorological data
The preliminary development and investigation of photovoltaic power plants should first obtain local meteorological data, analyze the local meteorological conditions, and determine whether it is suitable to build photovoltaic power plants in the area. If there is no weather station in the area, you can also obtain relevant weather data through free methods, such as the NASA website in the United States.
(3) Calculation model of solar radiation
The amount of solar radiation obtained on the horizontal plane and the inclined plane conforms to the principle of direct scattering and separation of light, that is, the total amount of radiation is equal to the sum of direct radiation and scattered radiation. The difference is that the radiation obtained on the photovoltaic module array surface also includes light. The radiation reflected on the surface of the module after being shot to the ground, but not on the horizontal plane, the weather station generally only provides solar radiation data measured on the horizontal plane. The amount of electricity a PV module can generate per hour is affected by many combined factors, including the average amount of solar radiation received by the module plane per hour, the surrounding ambient temperature, and other equipment characteristics. Since photovoltaic modules are mostly installed obliquely, when calculating the output of photovoltaic drop columns, it is necessary to reflect the recorded radiation intensity value on the measured horizontal plane to the inclined plane according to a certain relationship. Therefore, we need to go through a more complex mathematical model. to determine the amount of solar radiation on the inclined surface of the module. How to maximize the amount of solar radiation on the inclined plane is one of the key points in the study of the maximum power generation of photovoltaic power generation systems. Therefore, we first analyze the Klien model for calculating the amount of solar radiation.
The inclination angle is β and the solar radiation intensity of the inclined plane is expressed by the Klien model as:
Using the above formula, according to the local latitude and meteorological data, calculate the amount of solar radiation on the inclined plane with an inclination angle of 3 towards the equator.
(4) Solar cell power output calculation model
The output of the solar cell has a curve characteristic, which is affected by temperature, light intensity and electrical load. Under the specified temperature and light intensity, the output power of the photovoltaic system can reach the maximum value only at a specific output voltage, which is the Maximum power tracking technology for photovoltaic power generation systems. Solar cells are mainly affected by light. For example, when it is cloudy at night or during the day, the battery will have no output or a small output.
At present, there are many models for calculating the power output of solar cell modules, most of which need to consider many factors, the calculation is complicated, some parameters are difficult to obtain, and they are not practical.
(5) Calculation of optimal inclination angle and result analysis
①Analysis method The method adopted in this paper to calculate the optimal inclination angle can be called the arithmetic optimization method, and the specific calculation method is as follows. Based on the Klien model, the corresponding computer program is written according to the local geographical and meteorological data conditions, and the automatic calculation program is used to calculate and obtain the inclination angle corresponding to the maximum power generation. Radiation data and other related information. When the latitude is greater than the local latitude, the radiation value on the inclined plane is calculated in the range of -10″~+10″ of the local latitude with 1 as the equal difference value through the model. And compared with the last calculation result, the inclination angle corresponding to the maximum value is selected, and this inclination angle is the inclination angle corresponding to the maximum power generation. For the independent system, the calculation idea is the same as the above, but the optimization range is different. The optimization range of the independent system is within the range from the local latitude value to 30″ greater than the local latitude.
②Best inclination analysis of independent systems For off-grid photovoltaic power generation systems, the system generally requires a large amount of power in winter. But there are also special off-grid power supply systems, such as communication base stations and gas RTU control boxes, which require the system to generate more than 8,700 365 days a year. Hours of uninterrupted power supply. For this type of power supply system, the angle of the day with the smallest radiation in the year is the best, and the solar radiation is the smallest on the winter solstice. The winter solstice is the longest night and the shortest day. The street lights are turned on. It takes the longest time, that is, the inclination angle of the photovoltaic array is required to be adjusted to receive the maximum amount of solar radiation in winter, so as to ensure that the maximum power generation is generated on the winter solstice with a certain level of radiation on the horizontal plane.
③Analysis of optimal inclination angle of grid-connected system The installed capacity of grid-connected photovoltaic power plants is generally large. In order to obtain the maximum power generation, the choice of inclination angle is particularly important. In the design process of the solar photovoltaic power station, the inclination angle of the solar cell support installation has a great influence on the grid-connected photovoltaic power station’s on-grid power and the actual floor space of the photovoltaic power station. For the fixed installation method, the larger the inclination angle, the lower the installed capacity. Timing, the larger the area occupied.
By analyzing two inclined plane radiation calculation models, on the basis of the existing literature on module installation angle selection, based on the Klien model and related data, a new method of calculating solar radiation in equal hours is proposed to determine the module installation angle. At the same time, a new arithmetic optimization method for finding the best dip angle is proposed.
(6) Calculation of front and rear spacing of solar cell array
When the power of the photovoltaic power station is large, the solar cell arrays need to be arranged in the front and rear rows. When there are tall buildings or trees near the solar cell arrays, the shadows of the buildings or the front row arrays need to be calculated to determine the distance between the arrays. Or the distance between the solar cell array and the building. The general determination principle is: the solar cell array should not be blocked from 9:00 am to 3:00 pm on the winter solstice day.
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