Highway billboard photovoltaic power generation system, due to construction conditions and the user's consideration of cost, can not install too many solar panels on the top side of the billboard. In order to meet the power consumption of the spotlights for lighting at night, the system design should try to make full use of the limited components and enhance the power generation effect.
1. The factors affecting PV power generation include whether the system configuration is reasonable, whether the component lighting orientation is correct, whether the tilt angle of the component is reasonable, and the shadow of the PV system. Among them, PV system shadows include the shade of buildings around billboards, shade trees, modules overlapping each other, dust and bird droppings, etc. Photovoltaic shadow will have a great impact on the power generation efficiency of the system, and produce hot spot effect, shorten the life of the module, damage the module. Therefore, when installing solar panels, we should fully consider the impact of the actual operating conditions on PV cell output such as latitude, spectrum, temperature, shading, etc. of the geographic location of the billboard.
The so-called photovoltaic hot spot effect refers to the solar cell module under sunlight, because some components are shaded and cannot work, will be used as a load to consume the energy generated by other solar cell modules with light, making the covered part heating up much larger than the uncovered part, resulting in a dark spot with high temperature burnout. The hot spot effect may cause the whole module to be damaged.
In practice, in order to achieve the ideal photoelectric conversion efficiency, the series or parallel connection between components, must have similar characteristics, different specifications, different performance, different manufacturers of components can not be mixed.
2, photovoltaic module azimuth and tilt angle selected is one of the most important factors in the design of solar power generation systems. The so-called azimuth angle generally refers to the angle of east-west north-south direction, azimuth angle to the south as 0 °, from the south to the east to the north for the negative angle, from the south to the north of this for the lower angle. Such as the sun in the lower east direction, the azimuth angle of -90 °, in the positive west azimuth angle of 90 °. The azimuth angle determines the direction of incidence of sunlight and determines the component is the lighting condition. On a sunny summer day, the maximum solar radiation energy is later at noon, so the maximum power generation can be obtained in the late afternoon when the orientation of the array is slightly to the west. In different seasons, there are times when the solar cell array is oriented slightly to the east or west to obtain the maximum power generation.
The tilt angle is the angle between the ground plane (horizontal plane) and the solar cell module. A tilt angle of 0° means that the solar module is set horizontally, and a tilt angle of 90° means that the solar module is set vertically. The most ideal tilt angle is the one that makes the annual power generation of solar cells as large as possible, while the difference between winter and summer power generation is as small as possible.
3, in the weather without high wind blowing as well as rain washed by the billboard next to the highway, the surface of the solar panel is easy to accumulate thick dust, and birds in the nearby woods often stay and excrete on the surface of the module, which has a very large impact on the module power loss, and the power generation efficiency is reduced by at least 6%. However, in practice, people are unable to do regular wipe, cleaning components, this problem has always brought trouble.
4, outdoor billboard photovoltaic arrays are connected by multiple components in series and parallel. Series connection will cause current loss due to the difference in current of the components, and parallel connection will cause voltage loss due to the difference in voltage of the components. The combined loss can reach more than 8%, and the standard of China Engineering Construction Standardization Association stipulates less than 10%. In order to reduce the combined power loss, it is recommended to strictly select the components with the same current performance before purchasing and installation.
