What are the ten major factors that affect the power generation of solar photovoltaic power stations?

1. Solar energy resources

When the actual installed capacity of the photovoltaic power station is certain, the power generation of the photovoltaic system is determined by the radiation intensity of the sun, and the solar radiation is positively correlated with the power generation. The radiation intensity and spectral characteristics of the sun change with meteorological conditions.

2. Component installation method

The radiation of the inclined surface with different installation angles in the same area is different. The radiation of the inclined surface can be increased by adjusting the inclination of the solar panel (the bracket adopts a fixed adjustable type) or adding a tracking device (the bracket adopts a tracking type).

3. Inverter capacity ratio

The inverter capacity ratio refers to the ratio of the rated power of the inverter to the capacity of the photovoltaic module it carries.

Since the power generation of the photovoltaic module is transmitted to the inverter, there will be many links in the middle to cause reduction, and the inverter, box transformer and other equipment cannot reach full load operation most of the time. Therefore, the capacity of the photovoltaic module should be slightly larger than the rated capacity of the inverter. According to experience, in areas with good solar energy resources, photovoltaic module: inverter = 1.2:1 is a better design ratio.

4. Component series and parallel matching

Component series connection will cause current loss due to the current difference of components, and group series and parallel connection will cause voltage loss due to the voltage difference of groups.

CNCA/-"Technical Specifications for Performance Testing and Quality Assessment of Grid-connected Photovoltaic Power Stations" (Draft for Comments): It is required that the mismatch loss of component series connection should not exceed 2%.

5. Component shielding

Component shielding includes dust shielding, snow shielding, weeds, trees, solar panels and other buildings. Shielding will reduce the amount of radiation received by the component, affect the heat dissipation of the component, thereby causing the output power of the component to decrease, and may also cause hot spots.

6. Component temperature characteristics

As the temperature of crystalline silicon cells increases, the open circuit voltage decreases. In the 20-℃ range, the voltage of each cell decreases by about 2mV for every 1℃ increase; while the current increases slightly with the increase in temperature. In general, the power of solar cells decreases as the temperature increases. The typical power temperature coefficient is -0.35%/℃, that is, the power decreases by 0.35% for every 1℃ increase in the battery temperature.

7. Component power attenuation

Component power attenuation refers to the phenomenon that the output power of the component gradually decreases as the illumination time increases. Component attenuation is related to the characteristics of the component itself. Its attenuation phenomenon can be roughly divided into three categories: sudden attenuation of component power caused by destructive factors; initial light-induced attenuation of the component; aging attenuation of the component.

CNCA/-"Technical Specifications for Performance Testing and Quality Assessment of Grid-connected Photovoltaic Power Stations" The attenuation rate of polycrystalline silicon components shall not exceed 2.5% within 1 year and 3.2% within 2 years; the attenuation rate of monocrystalline silicon components shall not exceed 3.0% within 1 year and 4.2% within 2 years.

8. Equipment operation stability

Equipment failure and shutdown in the photovoltaic power generation system directly affects the power generation of the power station. If the AC equipment above the inverter fails and shuts down, the power loss will be huge. In addition, although the equipment is running but not running in the best performance state, it will also cause power loss.

9. Routine maintenance

Routine maintenance and repair are necessary for power stations. Arranging a good maintenance plan can reduce power loss. The power station should reasonably set the maintenance time according to its own situation, and at the same time improve the maintenance work efficiency to reduce the power generation loss of the power station due to normal maintenance and repair.

10. Grid absorption

Due to the reasons of grid absorption, some regional grid dispatching requires photovoltaic power stations to operate at limited power. Factors affecting the power generation of photovoltaic power stations include solar energy resources, component installation methods, inverter capacity ratio, component series and parallel matching, component shielding, component temperature characteristics, component power attenuation, equipment operation and maintenance stability, routine maintenance and grid absorption, etc. These factors all affect the power generation of the power station to varying degrees.