Reasons for Low Photovoltaic Power Generation (1)
After the photovoltaic system is installed, the user is most concerned about the power generation, because it is directly related to the user's return on investment. There are many factors that affect power generation, such as the quality of components, inverters, cables, azimuth angle of installation, tilt angle, dust, shadow shading, component, and inverter ratio system schemes, line design, construction, grid voltage, etc. Factors are possible. This series of articles will discuss various factors one by one based on actual cases. This series of articles mainly discuss the influence of component factors on the system
1. Dust on Component
For long-running photovoltaic power generation systems, the impact of panel dust on it should not be underestimated. The dust on the surface of the panel has the function of reflecting, scattering, and absorbing solar radiation, which can reduce the transmittance of the sun, causing the solar radiation received by the panel to decrease, and the output power is also reduced. Its effect is proportional to the cumulative thickness of the dust.
A. Dust influences the temperature of the component
At present, photovoltaic power plants mostly use silicon-based solar cell modules, which are very sensitive to temperature. As dust accumulates on the surface of the module, it increases the heat transfer resistance of the photovoltaic module and becomes the thermal insulation layer on the photovoltaic module, which affects its heat dissipation. . After the component is covered, the bypass protection element in the junction box behind it is induced to start. The DC current of up to about 9A in the component string will be instantly loaded on the bypass device, and a high temperature of more than 100 degrees will be generated in the junction box. This kind of high temperature has little effect on the battery board and the junction box in the short term, but if the shadow effect is not eliminated and exists for a long time, it will seriously affect the service life of the junction box and the battery board. In industry news reports, junction boxes are often burned, and shielding is one of the culprits.
The current and voltage of some cells in the solar cell module have changed. As a result, the product of the local current and voltage of the solar cell module is increased, and a local temperature rise is generated in these cell modules. The defects of some single cells in the solar cell module may also cause the module to locally generate heat during operation. This phenomenon is called the "hot spot effect". When the hot spot effect reaches a certain level, the solder joints on the components melt and destroy the grid lines, which leads to a scrap of the entire solar cell module. According to data provided by the industry, the hot spot effect reduces the actual service life of solar cell modules by at least 10%.
To be continued…
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